include/psa/crypto.h

/**
 * \file psa/crypto.h
 * \brief Platform Security Architecture cryptography module
 */
/*
 *  Copyright (C) 2018, ARM Limited, All Rights Reserved
 *  SPDX-License-Identifier: Apache-2.0
 *
 *  Licensed under the Apache License, Version 2.0 (the "License"); you may
 *  not use this file except in compliance with the License.
 *  You may obtain a copy of the License at
 *
 *  http://www.apache.org/licenses/LICENSE-2.0
 *
 *  Unless required by applicable law or agreed to in writing, software
 *  distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
 *  WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 *  See the License for the specific language governing permissions and
 *  limitations under the License.
 */

#ifndef PSA_CRYPTO_H
#define PSA_CRYPTO_H

#include "crypto_platform.h"

#include <stddef.h>

#ifdef __DOXYGEN_ONLY__
/* This __DOXYGEN_ONLY__ block contains mock definitions for things that
 * must be defined in the crypto_platform.h header. These mock definitions
 * are present in this file as a convenience to generate pretty-printed
 * documentation that includes those definitions. */

/** \defgroup platform Implementation-specific definitions
 * @{
 */

/** \brief Key handle.
 *
 * This type represents open handles to keys. It must be an unsigned integral
 * type. The choice of type is implementation-dependent.
 *
 * 0 is not a valid key handle. How other handle values are assigned is
 * implementation-dependent.
 */
typedef _unsigned_integral_type_ psa_key_handle_t;

/**@}*/
#endif /* __DOXYGEN_ONLY__ */

#ifdef __cplusplus
extern "C" {
#endif

/* The file "crypto_types.h" declares types that encode errors,
 * algorithms, key types, policies, etc. */
#include "crypto_types.h"

/* The file "crypto_values.h" declares macros to build and analyze values
 * of integral types defined in "crypto_types.h". */
#include "crypto_values.h"

/** \defgroup initialization Library initialization
 * @{
 */

/**
 * \brief Library initialization.
 *
 * Applications must call this function before calling any other
 * function in this module.
 *
 * Applications may call this function more than once. Once a call
 * succeeds, subsequent calls are guaranteed to succeed.
 *
 * If the application calls other functions before calling psa_crypto_init(),
 * the behavior is undefined. Implementations are encouraged to either perform
 * the operation as if the library had been initialized or to return
 * #PSA_ERROR_BAD_STATE or some other applicable error. In particular,
 * implementations should not return a success status if the lack of
 * initialization may have security implications, for example due to improper
 * seeding of the random number generator.
 *
 * \retval #PSA_SUCCESS
 * \retval #PSA_ERROR_INSUFFICIENT_MEMORY
 * \retval #PSA_ERROR_COMMUNICATION_FAILURE
 * \retval #PSA_ERROR_HARDWARE_FAILURE
 * \retval #PSA_ERROR_TAMPERING_DETECTED
 * \retval #PSA_ERROR_INSUFFICIENT_ENTROPY
 */
psa_status_t psa_crypto_init(void);

/**@}*/

/** \defgroup attributes Key attributes
 * @{
 */

/** The type of a structure containing key attributes.
 *
 * This is an opaque structure that can represent the metadata of a key
 * object. Metadata that can be stored in attributes includes:
 * - The location of the key in storage, indicated by its key identifier
 *   and its lifetime.
 * - The key's policy, comprising usage flags and a specification of
 *   the permitted algorithm(s).
 * - Information about the key itself: the key type, the key size, and
 *   for some key type additional domain parameters.
 * - Implementations may define additional attributes.
 *
 * The actual key material is not considered an attribute of a key.
 * Key attributes do not contain information that is generally considered
 * highly confidential.
 *
 * An attribute structure can be a simple data structure where each function
 * `psa_set_key_xxx` sets a field and the corresponding function
 * `psa_get_key_xxx` retrieves the value of the corresponding field.
 * However, implementations may report values that are equivalent to the
 * original one, but have a different encoding. For example, an
 * implementation may use a more compact representation for types where
 * many bit-patterns are invalid or not supported, and store all values
 * that it does not support as a special marker value. In such an
 * implementation, after setting an invalid value, the corresponding
 * get function returns an invalid value which may not be the one that
 * was originally stored.
 *
 * An attribute structure may contain references to auxiliary resources,
 * for example pointers to allocated memory or indirect references to
 * pre-calculated values. In order to free such resources, the application
 * must call psa_reset_key_attributes(). As an exception, calling
 * psa_reset_key_attributes() on an attribute structure is optional if
 * the structure has only been modified by the following functions
 * since it was initialized or last reset with psa_reset_key_attributes():
 * - psa_make_key_persistent()
 * - psa_set_key_type()
 * - psa_set_key_bits()
 * - psa_set_key_usage_flags()
 * - psa_set_key_algorithm()
 *
 * Before calling any function on a key attribute structure, the application
 * must initialize it by any of the following means:
 * - Set the structure to all-bits-zero, for example:
 *   \code
 *   psa_key_attributes_t attributes;
 *   memset(&attributes, 0, sizeof(attributes));
 *   \endcode
 * - Initialize the structure to logical zero values, for example:
 *   \code
 *   psa_key_attributes_t attributes = {0};
 *   \endcode
 * - Initialize the structure to the initializer #PSA_KEY_ATTRIBUTES_INIT,
 *   for example:
 *   \code
 *   psa_key_attributes_t attributes = PSA_KEY_ATTRIBUTES_INIT;
 *   \endcode
 * - Assign the result of the function psa_key_attributes_init()
 *   to the structure, for example:
 *   \code
 *   psa_key_attributes_t attributes;
 *   attributes = psa_key_attributes_init();
 *   \endcode
 *
 * A freshly initialized attribute structure contains the following
 * values:
 *
 * - lifetime: #PSA_KEY_LIFETIME_VOLATILE.
 * - key identifier: unspecified.
 * - type: \c 0, with no domain parameters.
 * - key size: \c 0.
 * - usage flags: \c 0.
 * - algorithm: \c 0.
 *
 * A typical sequence to create a key is as follows:
 * -# Create and initialize an attribute structure.
 * -# If the key is persistent, call psa_make_key_persistent().
 * -# Set the key policy with psa_set_key_usage_flags() and
 *    psa_set_key_algorithm().
 * -# Set the key type with psa_set_key_type(). If the key type requires
 *    domain parameters, call psa_set_key_domain_parameters() instead.
 *    Skip this step if copying an existing key with psa_copy_key().
 * -# When generating a random key with psa_generate_key() or deriving a key
 *    with psa_generator_import_key(), set the desired key size with
 *    psa_set_key_bits().
 * -# Call a key creation function: psa_import_key(), psa_generate_key(),
 *    psa_generator_import_key() or psa_copy_key().
 * -# The attribute structure is no longer necessary. If you called
 *    psa_set_key_domain_parameters() earlier, you must call
 *    psa_reset_key_attributes() to free any resources used by the
 *    domain parameters. Otherwise calling psa_reset_key_attributes()
 *    is optional.
 *
 * A typical sequence to query a key's attributes is as follows:
 * -# Call psa_get_key_attributes().
 * -# Call `psa_get_key_xxx` functions to retrieve the attribute(s) that
 *    you are interested in.
 * -# Call psa_reset_key_attributes() to free any resources that may be
 *    used by the attribute structure.
 *
 * Once a key has been created, it is impossible to change its attributes.
 */
typedef struct psa_key_attributes_s psa_key_attributes_t;

/** Declare a key as persistent.
 *
 * This function does not access storage, it merely fills the attribute
 * structure with given values. The persistent key will be written to
 * storage when the attribute structure is passed to a key creation
 * function such as psa_import_key(), psa_generate_key(),
 * psa_generator_import_key() or psa_copy_key().
 *
 * This function overwrites any identifier and lifetime values
 * previously set in \p attributes.
 *
 * This function may be declared as `static` (i.e. without external
 * linkage). This function may be provided as a function-like macro,
 * but in this case it must evaluate each of its arguments exactly once.
 *
 * \param[out] attributes       The attribute structure to write to.
 * \param id                    The persistent identifier for the key.
 * \param lifetime              The lifetime for the key.
 *                              If this is #PSA_KEY_LIFETIME_VOLATILE, the
 *                              key will be volatile, and \p id is ignored.
 */
static void psa_make_key_persistent(psa_key_attributes_t *attributes,
                                    psa_key_id_t id,
                                    psa_key_lifetime_t lifetime);

/** Retrieve the key identifier from key attributes.
 *
 * This function may be declared as `static` (i.e. without external
 * linkage). This function may be provided as a function-like macro,
 * but in this case it must evaluate its argument exactly once.
 *
 * \param[in] attributes        The key attribute structure to query.
 *
 * \return The persistent identifier stored in the attribute structure.
 *         This value is unspecified if the attribute structure declares
 *         the key as volatile.
 */
static psa_key_id_t psa_get_key_id(const psa_key_attributes_t *attributes);

/** Retrieve the lifetime from key attributes.
 *
 * This function may be declared as `static` (i.e. without external
 * linkage). This function may be provided as a function-like macro,
 * but in this case it must evaluate its argument exactly once.
 *
 * \param[in] attributes        The key attribute structure to query.
 *
 * \return The lifetime value stored in the attribute structure.
 */
static psa_key_lifetime_t psa_get_key_lifetime(
    const psa_key_attributes_t *attributes);

/** Declare usage flags for a key.
 *
 * Usage flags are part of a key's usage policy. They encode what
 * kind of operations are permitted on the key. For more details,
 * refer to the documentation of the type #psa_key_usage_t.
 *
 * This function overwrites any usage flags
 * previously set in \p attributes.
 *
 * This function may be declared as `static` (i.e. without external
 * linkage). This function may be provided as a function-like macro,
 * but in this case it must evaluate each of its arguments exactly once.
 *
 * \param[out] attributes       The attribute structure to write to.
 * \param usage_flags           The usage flags to write.
 */
static void psa_set_key_usage_flags(psa_key_attributes_t *attributes,
                                    psa_key_usage_t usage_flags);

/** Retrieve the usage flags from key attributes.
 *
 * This function may be declared as `static` (i.e. without external
 * linkage). This function may be provided as a function-like macro,
 * but in this case it must evaluate its argument exactly once.
 *
 * \param[in] attributes        The key attribute structure to query.
 *
 * \return The usage flags stored in the attribute structure.
 */
static psa_key_usage_t psa_get_key_usage_flags(
    const psa_key_attributes_t *attributes);

/** Declare the permitted algorithm policy for a key.
 *
 * The permitted algorithm policy of a key encodes which algorithm or
 * algorithms are permitted to be used with this key.
 *
 * This function overwrites any algorithm policy
 * previously set in \p attributes.
 *
 * This function may be declared as `static` (i.e. without external
 * linkage). This function may be provided as a function-like macro,
 * but in this case it must evaluate each of its arguments exactly once.
 *
 * \param[out] attributes       The attribute structure to write to.
 * \param alg                   The permitted algorithm policy to write.
 */
static void psa_set_key_algorithm(psa_key_attributes_t *attributes,
                                  psa_algorithm_t alg);

/** Retrieve the algorithm policy from key attributes.
 *
 * This function may be declared as `static` (i.e. without external
 * linkage). This function may be provided as a function-like macro,
 * but in this case it must evaluate its argument exactly once.
 *
 * \param[in] attributes        The key attribute structure to query.
 *
 * \return The algorithm stored in the attribute structure.
 */
static psa_algorithm_t psa_get_key_algorithm(
    const psa_key_attributes_t *attributes);

/** Declare the type of a key.
 *
 * If a type requires domain parameters, you must call
 * psa_set_key_domain_parameters() instead of this function.
 *
 * This function overwrites any key type and domain parameters
 * previously set in \p attributes.
 *
 * This function may be declared as `static` (i.e. without external
 * linkage). This function may be provided as a function-like macro,
 * but in this case it must evaluate each of its arguments exactly once.
 *
 * \param[out] attributes       The attribute structure to write to.
 * \param type                  The key type to write.
 */
static void psa_set_key_type(psa_key_attributes_t *attributes,
                             psa_key_type_t type);

/** Declare the size of a key.
 *
 * This function overwrites any key size previously set in \p attributes.
 *
 * This function may be declared as `static` (i.e. without external
 * linkage). This function may be provided as a function-like macro,
 * but in this case it must evaluate each of its arguments exactly once.
 *
 * \param[out] attributes       The attribute structure to write to.
 * \param bits                  The key size in bits.
 */
static void psa_set_key_bits(psa_key_attributes_t *attributes,
                             size_t bits);

/** Retrieve the key type from key attributes.
 *
 * This function may be declared as `static` (i.e. without external
 * linkage). This function may be provided as a function-like macro,
 * but in this case it must evaluate its argument exactly once.
 *
 * \param[in] attributes        The key attribute structure to query.
 *
 * \return The key type stored in the attribute structure.
 */
static psa_key_type_t psa_get_key_type(const psa_key_attributes_t *attributes);

/** Retrieve the key size from key attributes.
 *
 * This function may be declared as `static` (i.e. without external
 * linkage). This function may be provided as a function-like macro,
 * but in this case it must evaluate its argument exactly once.
 *
 * \param[in] attributes        The key attribute structure to query.
 *
 * \return The key size stored in the attribute structure, in bits.
 */
static size_t psa_get_key_bits(const psa_key_attributes_t *attributes);

/**
 * \brief Set domain parameters for a key.
 *
 * Some key types require additional domain parameters in addition to
 * the key type identifier and the key size.
 * The format for the required domain parameters varies by the key type.
 *
 * - For RSA keys (#PSA_KEY_TYPE_RSA_PUBLIC_KEY or #PSA_KEY_TYPE_RSA_KEYPAIR),
 *   the domain parameter data consists of the public exponent,
 *   represented as a big-endian integer with no leading zeros.
 *   This information is used when generating an RSA key pair.
 *   When importing a key, the public exponent is read from the imported
 *   key data and the exponent recorded in the attribute structure is ignored.
 *   As an exception, the public exponent 65537 is represented by an empty
 *   byte string.
 * - For DSA keys (#PSA_KEY_TYPE_DSA_PUBLIC_KEY or #PSA_KEY_TYPE_DSA_KEYPAIR),
 *   the `Dss-Parms` format as defined by RFC 3279 &sect;2.3.2.
 *   ```
 *   Dss-Parms ::= SEQUENCE  {
 *      p       INTEGER,
 *      q       INTEGER,
 *      g       INTEGER
 *   }
 *   ```
 * - For Diffie-Hellman key exchange keys (#PSA_KEY_TYPE_DH_PUBLIC_KEY or
 *   #PSA_KEY_TYPE_DH_KEYPAIR), the
 *   `DomainParameters` format as defined by RFC 3279 &sect;2.3.3.
 *   ```
 *   DomainParameters ::= SEQUENCE {
 *      p               INTEGER,                    -- odd prime, p=jq +1
 *      g               INTEGER,                    -- generator, g
 *      q               INTEGER,                    -- factor of p-1
 *      j               INTEGER OPTIONAL,           -- subgroup factor
 *      validationParms ValidationParms OPTIONAL
 *   }
 *   ValidationParms ::= SEQUENCE {
 *      seed            BIT STRING,
 *      pgenCounter     INTEGER
 *   }
 *   ```
 *
 * \note This function may allocate memory or other resources.
 *       Once you have called this function on an attribute structure,
 *       you must call psa_reset_key_attributes() to free these resources.
 *
 * \param[in,out] attributes    Attribute structure where the specified domain
 *                              parameters will be stored.
 *                              If this function fails, the content of
 *                              \p attributes is not modified.
 * \param type                  Key type (a \c PSA_KEY_TYPE_XXX value).
 * \param[in] data              Buffer containing the key domain parameters.
 *                              The content of this buffer is interpreted
 *                              according to \p type as described above.
 * \param data_length           Size of the \p data buffer in bytes.
 *
 * \retval #PSA_SUCCESS
 * \retval #PSA_ERROR_INVALID_ARGUMENT
 * \retval #PSA_ERROR_NOT_SUPPORTED
 * \retval #PSA_ERROR_INSUFFICIENT_MEMORY
 */
psa_status_t psa_set_key_domain_parameters(psa_key_attributes_t *attributes,
                                           psa_key_type_t type,
                                           const uint8_t *data,
                                           size_t data_length);

/**
 * \brief Get domain parameters for a key.
 *
 * Get the domain parameters for a key with this function, if any. The format
 * of the domain parameters written to \p data is specified in the
 * documentation for psa_set_key_domain_parameters().
 *
 * \param[in] attributes        The key attribute structure to query.
 * \param[out] data             On success, the key domain parameters.
 * \param data_size             Size of the \p data buffer in bytes.
 * \param[out] data_length      On success, the number of bytes
 *                              that make up the key domain parameters data.
 *
 * \retval #PSA_SUCCESS
 * \retval #PSA_ERROR_BUFFER_TOO_SMALL
 */
psa_status_t psa_get_key_domain_parameters(
    const psa_key_attributes_t *attributes,
    uint8_t *data,
    size_t data_size,
    size_t *data_length);

/** Retrieve the attributes of a key.
 *
 * This function first resets the attribute structure as with
 * psa_reset_key_attributes(). It then copies the attributes of
 * the given key into the given attribute structure.
 *
 * \note This function may allocate memory or other resources.
 *       Once you have called this function on an attribute structure,
 *       you must call psa_reset_key_attributes() to free these resources.
 *
 * \param[in] handle            Handle to the key to query.
 * \param[in,out] attributes    On success, the attributes of the key.
 *                              On failure, equivalent to a
 *                              freshly-initialized structure.
 *
 * \retval #PSA_SUCCESS
 * \retval #PSA_ERROR_INVALID_HANDLE
 * \retval #PSA_ERROR_INSUFFICIENT_MEMORY
 * \retval #PSA_ERROR_COMMUNICATION_FAILURE
 */
psa_status_t psa_get_key_attributes(psa_key_handle_t handle,
                                    psa_key_attributes_t *attributes);

/** Reset a key attribute structure to a freshly initialized state.
 *
 * You must initialize the attribute structure as described in the
 * documentation of the type #psa_key_attributes_t before calling this
 * function. Once the structure has been initialized, you may call this
 * function at any time.
 *
 * This function frees any auxiliary resources that the structure
 * may contain.
 *
 * \param[in,out] attributes    The attribute structure to reset.
 */
void psa_reset_key_attributes(psa_key_attributes_t *attributes);

/**@}*/

/** \defgroup key_management Key management
 * @{
 */

/** Open a handle to an existing persistent key.
 *
 * Open a handle to a key which was previously created with psa_create_key().
 *
 * \param lifetime      The lifetime of the key. This designates a storage
 *                      area where the key material is stored. This must not
 *                      be #PSA_KEY_LIFETIME_VOLATILE.
 * \param id            The persistent identifier of the key.
 * \param[out] handle   On success, a handle to a key slot which contains
 *                      the data and metadata loaded from the specified
 *                      persistent location.
 *
 * \retval #PSA_SUCCESS
 *         Success. The application can now use the value of `*handle`
 *         to access the newly allocated key slot.
 * \retval #PSA_ERROR_INSUFFICIENT_MEMORY
 * \retval #PSA_ERROR_DOES_NOT_EXIST
 * \retval #PSA_ERROR_INVALID_ARGUMENT
 *         \p lifetime is invalid, for example #PSA_KEY_LIFETIME_VOLATILE.
 * \retval #PSA_ERROR_INVALID_ARGUMENT
 *         \p id is invalid for the specified lifetime.
 * \retval #PSA_ERROR_NOT_SUPPORTED
 *         \p lifetime is not supported.
 * \retval #PSA_ERROR_NOT_PERMITTED
 *         The specified key exists, but the application does not have the
 *         permission to access it. Note that this specification does not
 *         define any way to create such a key, but it may be possible
 *         through implementation-specific means.
 */
psa_status_t psa_open_key(psa_key_lifetime_t lifetime,
                          psa_key_id_t id,
                          psa_key_handle_t *handle);

/** Close a key handle.
 *
 * If the handle designates a volatile key, destroy the key material and
 * free all associated resources, just like psa_destroy_key().
 *
 * If the handle designates a persistent key, free all resources associated
 * with the key in volatile memory. The key slot in persistent storage is
 * not affected and can be opened again later with psa_open_key().
 *
 * If the key is currently in use in a multipart operation,
 * the multipart operation is aborted.
 *
 * \param handle        The key handle to close.
 *
 * \retval #PSA_SUCCESS
 * \retval #PSA_ERROR_INVALID_HANDLE
 * \retval #PSA_ERROR_COMMUNICATION_FAILURE
 */
psa_status_t psa_close_key(psa_key_handle_t handle);

/**@}*/

/** \defgroup import_export Key import and export
 * @{
 */

/**
 * \brief Import a key in binary format.
 *
 * This function supports any output from psa_export_key(). Refer to the
 * documentation of psa_export_public_key() for the format of public keys
 * and to the documentation of psa_export_key() for the format for
 * other key types.
 *
 * This specification supports a single format for each key type.
 * Implementations may support other formats as long as the standard
 * format is supported. Implementations that support other formats
 * should ensure that the formats are clearly unambiguous so as to
 * minimize the risk that an invalid input is accidentally interpreted
 * according to a different format.
 *
 * \param[in] attributes    The attributes for the new key.
 *                          The key size field in \p attributes is
 *                          ignored; the actual key size is determined
 *                          from the \p data buffer.
 * \param[out] handle       On success, a handle to the newly created key.
 *                          \c 0 on failure.
 * \param[in] data    Buffer containing the key data. The content of this
 *                    buffer is interpreted according to the type and,
 *                    if applicable, domain parameters declared in
 *                    \p attributes.
 *                    All implementations must support at least the format
 *                    described in the documentation
 *                    of psa_export_key() or psa_export_public_key() for
 *                    the chosen type. Implementations may allow other
 *                    formats, but should be conservative: implementations
 *                    should err on the side of rejecting content if it
 *                    may be erroneous (e.g. wrong type or truncated data).
 * \param data_length Size of the \p data buffer in bytes.
 *
 * \retval #PSA_SUCCESS
 *         Success.
 *         If the key is persistent, the key material and the key's metadata
 *         have been saved to persistent storage.
 * \retval #PSA_ERROR_ALREADY_EXISTS
 *         This is an attempt to create a persistent key, and there is
 *         already a persistent key with the given identifier.
 * \retval #PSA_ERROR_NOT_SUPPORTED
 *         The key type or key size is not supported, either by the
 *         implementation in general or in this particular persistent location.
 * \retval #PSA_ERROR_INVALID_ARGUMENT
 *         The key attributes, as a whole, are invalid,
 *         or the key data is not correctly formatted.
 * \retval #PSA_ERROR_INSUFFICIENT_MEMORY
 * \retval #PSA_ERROR_INSUFFICIENT_STORAGE
 * \retval #PSA_ERROR_COMMUNICATION_FAILURE
 * \retval #PSA_ERROR_STORAGE_FAILURE
 * \retval #PSA_ERROR_HARDWARE_FAILURE
 * \retval #PSA_ERROR_TAMPERING_DETECTED
 * \retval #PSA_ERROR_BAD_STATE
 *         The library has not been previously initialized by psa_crypto_init().
 *         It is implementation-dependent whether a failure to initialize
 *         results in this error code.
 */
psa_status_t psa_import_key(const psa_key_attributes_t *attributes,
                            psa_key_handle_t *handle,
                            const uint8_t *data,
                            size_t data_length);

/**
 * \brief Destroy a key.
 *
 * This function destroys the content of the key slot from both volatile
 * memory and, if applicable, non-volatile storage. Implementations shall
 * make a best effort to ensure that any previous content of the slot is
 * unrecoverable.
 *
 * This function also erases any metadata such as policies and frees all
 * resources associated with the key.
 *
 * If the key is currently in use in a multipart operation,
 * the multipart operation is aborted.
 *
 * \param handle        Handle to the key slot to erase.
 *
 * \retval #PSA_SUCCESS
 *         The slot's content, if any, has been erased.
 * \retval #PSA_ERROR_NOT_PERMITTED
 *         The slot holds content and cannot be erased because it is
 *         read-only, either due to a policy or due to physical restrictions.
 * \retval #PSA_ERROR_INVALID_HANDLE
 * \retval #PSA_ERROR_COMMUNICATION_FAILURE
 *         There was an failure in communication with the cryptoprocessor.
 *         The key material may still be present in the cryptoprocessor.
 * \retval #PSA_ERROR_STORAGE_FAILURE
 *         The storage is corrupted. Implementations shall make a best effort
 *         to erase key material even in this stage, however applications
 *         should be aware that it may be impossible to guarantee that the
 *         key material is not recoverable in such cases.
 * \retval #PSA_ERROR_TAMPERING_DETECTED
 *         An unexpected condition which is not a storage corruption or
 *         a communication failure occurred. The cryptoprocessor may have
 *         been compromised.
 * \retval #PSA_ERROR_BAD_STATE
 *         The library has not been previously initialized by psa_crypto_init().
 *         It is implementation-dependent whether a failure to initialize
 *         results in this error code.
 */
psa_status_t psa_destroy_key(psa_key_handle_t handle);

/**
 * \brief Export a key in binary format.
 *
 * The output of this function can be passed to psa_import_key() to
 * create an equivalent object.
 *
 * If the implementation of psa_import_key() supports other formats
 * beyond the format specified here, the output from psa_export_key()
 * must use the representation specified here, not the original
 * representation.
 *
 * For standard key types, the output format is as follows:
 *
 * - For symmetric keys (including MAC keys), the format is the
 *   raw bytes of the key.
 * - For DES, the key data consists of 8 bytes. The parity bits must be
 *   correct.
 * - For Triple-DES, the format is the concatenation of the
 *   two or three DES keys.
 * - For RSA key pairs (#PSA_KEY_TYPE_RSA_KEYPAIR), the format
 *   is the non-encrypted DER encoding of the representation defined by
 *   PKCS\#1 (RFC 8017) as `RSAPrivateKey`, version 0.
 *   ```
 *   RSAPrivateKey ::= SEQUENCE {
 *       version             INTEGER,  -- must be 0
 *       modulus             INTEGER,  -- n
 *       publicExponent      INTEGER,  -- e
 *       privateExponent     INTEGER,  -- d
 *       prime1              INTEGER,  -- p
 *       prime2              INTEGER,  -- q
 *       exponent1           INTEGER,  -- d mod (p-1)
 *       exponent2           INTEGER,  -- d mod (q-1)
 *       coefficient         INTEGER,  -- (inverse of q) mod p
 *   }
 *   ```
 * - For DSA private keys (#PSA_KEY_TYPE_DSA_KEYPAIR), the format is the
 *   representation of the private key `x` as a big-endian byte string. The
 *   length of the byte string is the private key size in bytes (leading zeroes
 *   are not stripped).
 * - For elliptic curve key pairs (key types for which
 *   #PSA_KEY_TYPE_IS_ECC_KEYPAIR is true), the format is
 *   a representation of the private value as a `ceiling(m/8)`-byte string
 *   where `m` is the bit size associated with the curve, i.e. the bit size
 *   of the order of the curve's coordinate field. This byte string is
 *   in little-endian order for Montgomery curves (curve types
 *   `PSA_ECC_CURVE_CURVEXXX`), and in big-endian order for Weierstrass
 *   curves (curve types `PSA_ECC_CURVE_SECTXXX`, `PSA_ECC_CURVE_SECPXXX`
 *   and `PSA_ECC_CURVE_BRAINPOOL_PXXX`).
 *   This is the content of the `privateKey` field of the `ECPrivateKey`
 *   format defined by RFC 5915.
 * - For Diffie-Hellman key exchange key pairs (#PSA_KEY_TYPE_DH_KEYPAIR), the
 *   format is the representation of the private key `x` as a big-endian byte
 *   string. The length of the byte string is the private key size in bytes
 *   (leading zeroes are not stripped).
 * - For public keys (key types for which #PSA_KEY_TYPE_IS_PUBLIC_KEY is
 *   true), the format is the same as for psa_export_public_key().
 *
 * \param handle            Handle to the key to export.
 * \param[out] data         Buffer where the key data is to be written.
 * \param data_size         Size of the \p data buffer in bytes.
 * \param[out] data_length  On success, the number of bytes
 *                          that make up the key data.
 *
 * \retval #PSA_SUCCESS
 * \retval #PSA_ERROR_INVALID_HANDLE
 * \retval #PSA_ERROR_DOES_NOT_EXIST
 * \retval #PSA_ERROR_NOT_PERMITTED
 * \retval #PSA_ERROR_NOT_SUPPORTED
 * \retval #PSA_ERROR_BUFFER_TOO_SMALL
 *         The size of the \p data buffer is too small. You can determine a
 *         sufficient buffer size by calling
 *         #PSA_KEY_EXPORT_MAX_SIZE(\c type, \c bits)
 *         where \c type is the key type
 *         and \c bits is the key size in bits.
 * \retval #PSA_ERROR_COMMUNICATION_FAILURE
 * \retval #PSA_ERROR_HARDWARE_FAILURE
 * \retval #PSA_ERROR_TAMPERING_DETECTED
 * \retval #PSA_ERROR_BAD_STATE
 *         The library has not been previously initialized by psa_crypto_init().
 *         It is implementation-dependent whether a failure to initialize
 *         results in this error code.
 */
psa_status_t psa_export_key(psa_key_handle_t handle,
                            uint8_t *data,
                            size_t data_size,
                            size_t *data_length);

/**
 * \brief Export a public key or the public part of a key pair in binary format.
 *
 * The output of this function can be passed to psa_import_key() to
 * create an object that is equivalent to the public key.
 *
 * This specification supports a single format for each key type.
 * Implementations may support other formats as long as the standard
 * format is supported. Implementations that support other formats
 * should ensure that the formats are clearly unambiguous so as to
 * minimize the risk that an invalid input is accidentally interpreted
 * according to a different format.
 *
 * For standard key types, the output format is as follows:
 * - For RSA public keys (#PSA_KEY_TYPE_RSA_PUBLIC_KEY), the DER encoding of
 *   the representation defined by RFC 3279 &sect;2.3.1 as `RSAPublicKey`.
 *   ```
 *   RSAPublicKey ::= SEQUENCE {
 *      modulus            INTEGER,    -- n
 *      publicExponent     INTEGER  }  -- e
 *   ```
 * - For elliptic curve public keys (key types for which
 *   #PSA_KEY_TYPE_IS_ECC_PUBLIC_KEY is true), the format is the uncompressed
 *   representation defined by SEC1 &sect;2.3.3 as the content of an ECPoint.
 *   Let `m` be the bit size associated with the curve, i.e. the bit size of
 *   `q` for a curve over `F_q`. The representation consists of:
 *      - The byte 0x04;
 *      - `x_P` as a `ceiling(m/8)`-byte string, big-endian;
 *      - `y_P` as a `ceiling(m/8)`-byte string, big-endian.
 * - For DSA public keys (#PSA_KEY_TYPE_DSA_PUBLIC_KEY), the format is the
 *   representation of the public key `y = g^x mod p` as a big-endian byte
 *   string. The length of the byte string is the length of the base prime `p`
 *   in bytes.
 * - For Diffie-Hellman key exchange public keys (#PSA_KEY_TYPE_DH_PUBLIC_KEY),
 *   the format is the representation of the public key `y = g^x mod p` as a
 *   big-endian byte string. The length of the byte string is the length of the
 *   base prime `p` in bytes.
 *
 * \param handle            Handle to the key to export.
 * \param[out] data         Buffer where the key data is to be written.
 * \param data_size         Size of the \p data buffer in bytes.
 * \param[out] data_length  On success, the number of bytes
 *                          that make up the key data.
 *
 * \retval #PSA_SUCCESS
 * \retval #PSA_ERROR_INVALID_HANDLE
 * \retval #PSA_ERROR_DOES_NOT_EXIST
 * \retval #PSA_ERROR_INVALID_ARGUMENT
 *         The key is neither a public key nor a key pair.
 * \retval #PSA_ERROR_NOT_SUPPORTED
 * \retval #PSA_ERROR_BUFFER_TOO_SMALL
 *         The size of the \p data buffer is too small. You can determine a
 *         sufficient buffer size by calling
 *         #PSA_KEY_EXPORT_MAX_SIZE(#PSA_KEY_TYPE_PUBLIC_KEY_OF_KEYPAIR(\c type), \c bits)
 *         where \c type is the key type
 *         and \c bits is the key size in bits.
 * \retval #PSA_ERROR_COMMUNICATION_FAILURE
 * \retval #PSA_ERROR_HARDWARE_FAILURE
 * \retval #PSA_ERROR_TAMPERING_DETECTED
 * \retval #PSA_ERROR_BAD_STATE
 *         The library has not been previously initialized by psa_crypto_init().
 *         It is implementation-dependent whether a failure to initialize
 *         results in this error code.
 */
psa_status_t psa_export_public_key(psa_key_handle_t handle,
                                   uint8_t *data,
                                   size_t data_size,
                                   size_t *data_length);

/** Make a copy of a key.
 *
 * Copy key material from one location to another.
 *
 * This function is primarily useful to copy a key from one location
 * to another, since it populates a key using the material from
 * another key which may have a different lifetime.
 *
 * In an implementation where slots have different ownerships,
 * this function may be used to share a key with a different party,
 * subject to implementation-defined restrictions on key sharing.
 *
 * The resulting key may only be used in a way that conforms to
 * both the policy of the original key and the policy specified in
 * the \p attributes parameter:
 * - The usage flags on the resulting key are the bitwise-and of the
 *   usage flags on the source policy and the usage flags in \p attributes.
 * - If both allow the same algorithm or wildcard-based
 *   algorithm policy, the resulting key has the same algorithm policy.
 * - If either of the policies allows an algorithm and the other policy
 *   allows a wildcard-based algorithm policy that includes this algorithm,
 *   the resulting key allows the same algorithm.
 * - If the policies do not allow any algorithm in common, this function
 *   fails with the status #PSA_ERROR_INVALID_ARGUMENT.
 *
 * The effect of this function on implementation-defined attributes is
 * implementation-defined.
 *
 * \param source_handle     The key to copy. It must be a handle to an
 *                          occupied slot.
 * \param[in] attributes    The attributes for the new key.
 *                          They are used as follows:
 *                          - The key type, key size and domain parameters
 *                            are ignored. This information is copied
 *                            from the source key.
 *                          - The key location (the lifetime and, for
 *                            persistent keys, the key identifier) is
 *                            used directly.
 *                          - The policy constraints (usage flags and
 *                            algorithm policy) are combined from
 *                            the source key and \p attributes so that
 *                            both sets of restrictions apply, as
 *                            described in the documentation of this function.
 * \param[out] target_handle On success, a handle to the newly created key.
 *                          \c 0 on failure.
 *
 * \retval #PSA_SUCCESS
 * \retval #PSA_ERROR_INVALID_HANDLE
 *         \p source_handle is invalid.
 * \retval #PSA_ERROR_ALREADY_EXISTS
 *         This is an attempt to create a persistent key, and there is
 *         already a persistent key with the given identifier.
 * \retval #PSA_ERROR_INVALID_ARGUMENT
 *         The lifetime or identifier in \p attributes are invalid.
 * \retval #PSA_ERROR_INVALID_ARGUMENT
 *         The policy constraints on the source and specified in
 *         \p attributes are incompatible.
 * \retval #PSA_ERROR_NOT_PERMITTED
 *         The source key is not exportable and its lifetime does not
 *         allow copying it to the target's lifetime.
 * \retval #PSA_ERROR_INSUFFICIENT_MEMORY
 * \retval #PSA_ERROR_INSUFFICIENT_STORAGE
 * \retval #PSA_ERROR_COMMUNICATION_FAILURE
 * \retval #PSA_ERROR_HARDWARE_FAILURE
 * \retval #PSA_ERROR_TAMPERING_DETECTED
 */
psa_status_t psa_copy_key(psa_key_handle_t source_handle,
                          const psa_key_attributes_t *attributes,
                          psa_key_handle_t *target_handle);

/**@}*/

/** \defgroup hash Message digests
 * @{
 */

/** Calculate the hash (digest) of a message.
 *
 * \note To verify the hash of a message against an
 *       expected value, use psa_hash_compare() instead.
 *
 * \param alg               The hash algorithm to compute (\c PSA_ALG_XXX value
 *                          such that #PSA_ALG_IS_HASH(\p alg) is true).
 * \param[in] input         Buffer containing the message to hash.
 * \param input_length      Size of the \p input buffer in bytes.
 * \param[out] hash         Buffer where the hash is to be written.
 * \param hash_size         Size of the \p hash buffer in bytes.
 * \param[out] hash_length  On success, the number of bytes
 *                          that make up the hash value. This is always
 *                          #PSA_HASH_SIZE(\p alg).
 *
 * \retval #PSA_SUCCESS
 *         Success.
 * \retval #PSA_ERROR_NOT_SUPPORTED
 *         \p alg is not supported or is not a hash algorithm.
 * \retval #PSA_ERROR_INSUFFICIENT_MEMORY
 * \retval #PSA_ERROR_COMMUNICATION_FAILURE
 * \retval #PSA_ERROR_HARDWARE_FAILURE
 * \retval #PSA_ERROR_TAMPERING_DETECTED
 */
psa_status_t psa_hash_compute(psa_algorithm_t alg,
                              const uint8_t *input,
                              size_t input_length,
                              uint8_t *hash,
                              size_t hash_size,
                              size_t *hash_length);

/** Calculate the hash (digest) of a message and compare it with a
 * reference value.
 *
 * \param alg               The hash algorithm to compute (\c PSA_ALG_XXX value
 *                          such that #PSA_ALG_IS_HASH(\p alg) is true).
 * \param[in] input         Buffer containing the message to hash.
 * \param input_length      Size of the \p input buffer in bytes.
 * \param[out] hash         Buffer containing the expected hash value.
 * \param hash_length       Size of the \p hash buffer in bytes.
 *
 * \retval #PSA_SUCCESS
 *         The expected hash is identical to the actual hash of the input.
 * \retval #PSA_ERROR_INVALID_SIGNATURE
 *         The hash of the message was calculated successfully, but it
 *         differs from the expected hash.
 * \retval #PSA_ERROR_NOT_SUPPORTED
 *         \p alg is not supported or is not a hash algorithm.
 * \retval #PSA_ERROR_INSUFFICIENT_MEMORY
 * \retval #PSA_ERROR_COMMUNICATION_FAILURE
 * \retval #PSA_ERROR_HARDWARE_FAILURE
 * \retval #PSA_ERROR_TAMPERING_DETECTED
 */
psa_status_t psa_hash_compare(psa_algorithm_t alg,
                              const uint8_t *input,
                              size_t input_length,
                              const uint8_t *hash,
                              const size_t hash_length);

/** The type of the state data structure for multipart hash operations.
 *
 * Before calling any function on a hash operation object, the application must
 * initialize it by any of the following means:
 * - Set the structure to all-bits-zero, for example:
 *   \code
 *   psa_hash_operation_t operation;
 *   memset(&operation, 0, sizeof(operation));
 *   \endcode
 * - Initialize the structure to logical zero values, for example:
 *   \code
 *   psa_hash_operation_t operation = {0};
 *   \endcode
 * - Initialize the structure to the initializer #PSA_HASH_OPERATION_INIT,
 *   for example:
 *   \code
 *   psa_hash_operation_t operation = PSA_HASH_OPERATION_INIT;
 *   \endcode
 * - Assign the result of the function psa_hash_operation_init()
 *   to the structure, for example:
 *   \code
 *   psa_hash_operation_t operation;
 *   operation = psa_hash_operation_init();
 *   \endcode
 *
 * This is an implementation-defined \c struct. Applications should not
 * make any assumptions about the content of this structure except
 * as directed by the documentation of a specific implementation. */
typedef struct psa_hash_operation_s psa_hash_operation_t;

/** \def PSA_HASH_OPERATION_INIT
 *
 * This macro returns a suitable initializer for a hash operation object
 * of type #psa_hash_operation_t.
 */
#ifdef __DOXYGEN_ONLY__
/* This is an example definition for documentation purposes.
 * Implementations should define a suitable value in `crypto_struct.h`.
 */
#define PSA_HASH_OPERATION_INIT {0}
#endif

/** Return an initial value for a hash operation object.
 */
static psa_hash_operation_t psa_hash_operation_init(void);

/** Set up a multipart hash operation.
 *
 * The sequence of operations to calculate a hash (message digest)
 * is as follows:
 * -# Allocate an operation object which will be passed to all the functions
 *    listed here.
 * -# Initialize the operation object with one of the methods described in the
 *    documentation for #psa_hash_operation_t, e.g. PSA_HASH_OPERATION_INIT.
 * -# Call psa_hash_setup() to specify the algorithm.
 * -# Call psa_hash_update() zero, one or more times, passing a fragment
 *    of the message each time. The hash that is calculated is the hash
 *    of the concatenation of these messages in order.
 * -# To calculate the hash, call psa_hash_finish().
 *    To compare the hash with an expected value, call psa_hash_verify().
 *
 * The application may call psa_hash_abort() at any time after the operation
 * has been initialized.
 *
 * After a successful call to psa_hash_setup(), the application must
 * eventually terminate the operation. The following events terminate an
 * operation:
 * - A failed call to psa_hash_update().
 * - A call to psa_hash_finish(), psa_hash_verify() or psa_hash_abort().
 *
 * \param[in,out] operation The operation object to set up. It must have
 *                          been initialized as per the documentation for
 *                          #psa_hash_operation_t and not yet in use.
 * \param alg               The hash algorithm to compute (\c PSA_ALG_XXX value
 *                          such that #PSA_ALG_IS_HASH(\p alg) is true).
 *
 * \retval #PSA_SUCCESS
 *         Success.
 * \retval #PSA_ERROR_NOT_SUPPORTED
 *         \p alg is not supported or is not a hash algorithm.
 * \retval #PSA_ERROR_BAD_STATE
 *         The operation state is not valid (already set up and not
 *         subsequently completed).
 * \retval #PSA_ERROR_INSUFFICIENT_MEMORY
 * \retval #PSA_ERROR_COMMUNICATION_FAILURE
 * \retval #PSA_ERROR_HARDWARE_FAILURE
 * \retval #PSA_ERROR_TAMPERING_DETECTED
 */
psa_status_t psa_hash_setup(psa_hash_operation_t *operation,
                            psa_algorithm_t alg);

/** Add a message fragment to a multipart hash operation.
 *
 * The application must call psa_hash_setup() before calling this function.
 *
 * If this function returns an error status, the operation becomes inactive.
 *
 * \param[in,out] operation Active hash operation.
 * \param[in] input         Buffer containing the message fragment to hash.
 * \param input_length      Size of the \p input buffer in bytes.
 *
 * \retval #PSA_SUCCESS
 *         Success.
 * \retval #PSA_ERROR_BAD_STATE
 *         The operation state is not valid (not set up, or already completed).
 * \retval #PSA_ERROR_INSUFFICIENT_MEMORY
 * \retval #PSA_ERROR_COMMUNICATION_FAILURE
 * \retval #PSA_ERROR_HARDWARE_FAILURE
 * \retval #PSA_ERROR_TAMPERING_DETECTED
 */
psa_status_t psa_hash_update(psa_hash_operation_t *operation,
                             const uint8_t *input,
                             size_t input_length);

/** Finish the calculation of the hash of a message.
 *
 * The application must call psa_hash_setup() before calling this function.
 * This function calculates the hash of the message formed by concatenating
 * the inputs passed to preceding calls to psa_hash_update().
 *
 * When this function returns, the operation becomes inactive.
 *
 * \warning Applications should not call this function if they expect
 *          a specific value for the hash. Call psa_hash_verify() instead.
 *          Beware that comparing integrity or authenticity data such as
 *          hash values with a function such as \c memcmp is risky
 *          because the time taken by the comparison may leak information
 *          about the hashed data which could allow an attacker to guess
 *          a valid hash and thereby bypass security controls.
 *
 * \param[in,out] operation     Active hash operation.
 * \param[out] hash             Buffer where the hash is to be written.
 * \param hash_size             Size of the \p hash buffer in bytes.
 * \param[out] hash_length      On success, the number of bytes
 *                              that make up the hash value. This is always
 *                              #PSA_HASH_SIZE(\c alg) where \c alg is the
 *                              hash algorithm that is calculated.
 *
 * \retval #PSA_SUCCESS
 *         Success.
 * \retval #PSA_ERROR_BAD_STATE
 *         The operation state is not valid (not set up, or already completed).
 * \retval #PSA_ERROR_BUFFER_TOO_SMALL
 *         The size of the \p hash buffer is too small. You can determine a
 *         sufficient buffer size by calling #PSA_HASH_SIZE(\c alg)
 *         where \c alg is the hash algorithm that is calculated.
 * \retval #PSA_ERROR_INSUFFICIENT_MEMORY
 * \retval #PSA_ERROR_COMMUNICATION_FAILURE
 * \retval #PSA_ERROR_HARDWARE_FAILURE
 * \retval #PSA_ERROR_TAMPERING_DETECTED
 */
psa_status_t psa_hash_finish(psa_hash_operation_t *operation,
                             uint8_t *hash,
                             size_t hash_size,
                             size_t *hash_length);

/** Finish the calculation of the hash of a message and compare it with
 * an expected value.
 *
 * The application must call psa_hash_setup() before calling this function.
 * This function calculates the hash of the message formed by concatenating
 * the inputs passed to preceding calls to psa_hash_update(). It then
 * compares the calculated hash with the expected hash passed as a
 * parameter to this function.
 *
 * When this function returns, the operation becomes inactive.
 *
 * \note Implementations shall make the best effort to ensure that the
 * comparison between the actual hash and the expected hash is performed
 * in constant time.
 *
 * \param[in,out] operation     Active hash operation.
 * \param[in] hash              Buffer containing the expected hash value.
 * \param hash_length           Size of the \p hash buffer in bytes.
 *
 * \retval #PSA_SUCCESS
 *         The expected hash is identical to the actual hash of the message.
 * \retval #PSA_ERROR_INVALID_SIGNATURE
 *         The hash of the message was calculated successfully, but it
 *         differs from the expected hash.
 * \retval #PSA_ERROR_BAD_STATE
 *         The operation state is not valid (not set up, or already completed).
 * \retval #PSA_ERROR_INSUFFICIENT_MEMORY
 * \retval #PSA_ERROR_COMMUNICATION_FAILURE
 * \retval #PSA_ERROR_HARDWARE_FAILURE
 * \retval #PSA_ERROR_TAMPERING_DETECTED
 */
psa_status_t psa_hash_verify(psa_hash_operation_t *operation,
                             const uint8_t *hash,
                             size_t hash_length);

/** Abort a hash operation.
 *
 * Aborting an operation frees all associated resources except for the
 * \p operation structure itself. Once aborted, the operation object
 * can be reused for another operation by calling
 * psa_hash_setup() again.
 *
 * You may call this function any time after the operation object has
 * been initialized by any of the following methods:
 * - A call to psa_hash_setup(), whether it succeeds or not.
 * - Initializing the \c struct to all-bits-zero.
 * - Initializing the \c struct to logical zeros, e.g.
 *   `psa_hash_operation_t operation = {0}`.
 *
 * In particular, calling psa_hash_abort() after the operation has been
 * terminated by a call to psa_hash_abort(), psa_hash_finish() or
 * psa_hash_verify() is safe and has no effect.
 *
 * \param[in,out] operation     Initialized hash operation.
 *
 * \retval #PSA_SUCCESS
 * \retval #PSA_ERROR_BAD_STATE
 *         \p operation is not an active hash operation.
 * \retval #PSA_ERROR_COMMUNICATION_FAILURE
 * \retval #PSA_ERROR_HARDWARE_FAILURE
 * \retval #PSA_ERROR_TAMPERING_DETECTED
 */
psa_status_t psa_hash_abort(psa_hash_operation_t *operation);

/** Clone a hash operation.
 *
 * This function copies the state of an ongoing hash operation to
 * a new operation object. In other words, this function is equivalent
 * to calling psa_hash_setup() on \p target_operation with the same
 * algorithm that \p source_operation was set up for, then
 * psa_hash_update() on \p target_operation with the same input that
 * that was passed to \p source_operation. After this function returns, the
 * two objects are independent, i.e. subsequent calls involving one of
 * the objects do not affect the other object.
 *
 * \param[in] source_operation      The active hash operation to clone.
 * \param[in,out] target_operation  The operation object to set up.
 *                                  It must be initialized but not active.
 *
 * \retval #PSA_SUCCESS
 * \retval #PSA_ERROR_BAD_STATE
 *         \p source_operation is not an active hash operation.
 * \retval #PSA_ERROR_BAD_STATE
 *         \p target_operation is active.
 * \retval #PSA_ERROR_COMMUNICATION_FAILURE
 * \retval #PSA_ERROR_HARDWARE_FAILURE
 * \retval #PSA_ERROR_TAMPERING_DETECTED
 */
psa_status_t psa_hash_clone(const psa_hash_operation_t *source_operation,
                            psa_hash_operation_t *target_operation);

/**@}*/

/** \defgroup MAC Message authentication codes
 * @{
 */

/** Calculate the MAC (message authentication code) of a message.
 *
 * \note To verify the MAC of a message against an
 *       expected value, use psa_mac_verify() instead.
 *       Beware that comparing integrity or authenticity data such as
 *       MAC values with a function such as \c memcmp is risky
 *       because the time taken by the comparison may leak information
 *       about the MAC value which could allow an attacker to guess
 *       a valid MAC and thereby bypass security controls.
 *
 * \param handle            Handle to the key to use for the operation.
 * \param alg               The MAC algorithm to compute (\c PSA_ALG_XXX value
 *                          such that #PSA_ALG_IS_MAC(\p alg) is true).
 * \param[in] input         Buffer containing the input message.
 * \param input_length      Size of the \p input buffer in bytes.
 * \param[out] mac          Buffer where the MAC value is to be written.
 * \param mac_size          Size of the \p mac buffer in bytes.
 * \param[out] mac_length   On success, the number of bytes
 *                          that make up the MAC value.
 *
 * \retval #PSA_SUCCESS
 *         Success.
 * \retval #PSA_ERROR_INVALID_HANDLE
 * \retval #PSA_ERROR_EMPTY_SLOT
 * \retval #PSA_ERROR_NOT_PERMITTED
 * \retval #PSA_ERROR_INVALID_ARGUMENT
 *         \p handle is not compatible with \p alg.
 * \retval #PSA_ERROR_NOT_SUPPORTED
 *         \p alg is not supported or is not a MAC algorithm.
 * \retval #PSA_ERROR_INSUFFICIENT_MEMORY
 * \retval #PSA_ERROR_COMMUNICATION_FAILURE
 * \retval #PSA_ERROR_HARDWARE_FAILURE
 * \retval #PSA_ERROR_TAMPERING_DETECTED
 * \retval #PSA_ERROR_BAD_STATE
 *         The library has not been previously initialized by psa_crypto_init().
 *         It is implementation-dependent whether a failure to initialize
 *         results in this error code.
 */
psa_status_t psa_mac_compute(psa_key_handle_t handle,
                             psa_algorithm_t alg,
                             const uint8_t *input,
                             size_t input_length,
                             uint8_t *mac,
                             size_t mac_size,
                             size_t *mac_length);

/** Calculate the MAC of a message and compare it with a reference value.
 *
 * \param handle            Handle to the key to use for the operation.
 * \param alg               The MAC algorithm to compute (\c PSA_ALG_XXX value
 *                          such that #PSA_ALG_IS_MAC(\p alg) is true).
 * \param[in] input         Buffer containing the input message.
 * \param input_length      Size of the \p input buffer in bytes.
 * \param[out] mac          Buffer containing the expected MAC value.
 * \param mac_length        Size of the \p mac buffer in bytes.
 *
 * \retval #PSA_SUCCESS
 *         The expected MAC is identical to the actual MAC of the input.
 * \retval #PSA_ERROR_INVALID_SIGNATURE
 *         The MAC of the message was calculated successfully, but it
 *         differs from the expected value.
 * \retval #PSA_ERROR_INVALID_HANDLE
 * \retval #PSA_ERROR_EMPTY_SLOT
 * \retval #PSA_ERROR_NOT_PERMITTED
 * \retval #PSA_ERROR_INVALID_ARGUMENT
 *         \p handle is not compatible with \p alg.
 * \retval #PSA_ERROR_NOT_SUPPORTED
 *         \p alg is not supported or is not a MAC algorithm.
 * \retval #PSA_ERROR_INSUFFICIENT_MEMORY
 * \retval #PSA_ERROR_COMMUNICATION_FAILURE
 * \retval #PSA_ERROR_HARDWARE_FAILURE
 * \retval #PSA_ERROR_TAMPERING_DETECTED
 */
psa_status_t psa_mac_verify(psa_key_handle_t handle,
                            psa_algorithm_t alg,
                            const uint8_t *input,
                            size_t input_length,
                            const uint8_t *mac,
                            const size_t mac_length);

/** The type of the state data structure for multipart MAC operations.
 *
 * Before calling any function on a MAC operation object, the application must
 * initialize it by any of the following means:
 * - Set the structure to all-bits-zero, for example:
 *   \code
 *   psa_mac_operation_t operation;
 *   memset(&operation, 0, sizeof(operation));
 *   \endcode
 * - Initialize the structure to logical zero values, for example:
 *   \code
 *   psa_mac_operation_t operation = {0};
 *   \endcode
 * - Initialize the structure to the initializer #PSA_MAC_OPERATION_INIT,
 *   for example:
 *   \code
 *   psa_mac_operation_t operation = PSA_MAC_OPERATION_INIT;
 *   \endcode
 * - Assign the result of the function psa_mac_operation_init()
 *   to the structure, for example:
 *   \code
 *   psa_mac_operation_t operation;
 *   operation = psa_mac_operation_init();
 *   \endcode
 *
 * This is an implementation-defined \c struct. Applications should not
 * make any assumptions about the content of this structure except
 * as directed by the documentation of a specific implementation. */
typedef struct psa_mac_operation_s psa_mac_operation_t;

/** \def PSA_MAC_OPERATION_INIT
 *
 * This macro returns a suitable initializer for a MAC operation object of type
 * #psa_mac_operation_t.
 */
#ifdef __DOXYGEN_ONLY__
/* This is an example definition for documentation purposes.
 * Implementations should define a suitable value in `crypto_struct.h`.
 */
#define PSA_MAC_OPERATION_INIT {0}
#endif

/** Return an initial value for a MAC operation object.
 */
static psa_mac_operation_t psa_mac_operation_init(void);

/** Set up a multipart MAC calculation operation.
 *
 * This function sets up the calculation of the MAC
 * (message authentication code) of a byte string.
 * To verify the MAC of a message against an
 * expected value, use psa_mac_verify_setup() instead.
 *
 * The sequence of operations to calculate a MAC is as follows:
 * -# Allocate an operation object which will be passed to all the functions
 *    listed here.
 * -# Initialize the operation object with one of the methods described in the
 *    documentation for #psa_mac_operation_t, e.g. PSA_MAC_OPERATION_INIT.
 * -# Call psa_mac_sign_setup() to specify the algorithm and key.
 * -# Call psa_mac_update() zero, one or more times, passing a fragment
 *    of the message each time. The MAC that is calculated is the MAC
 *    of the concatenation of these messages in order.
 * -# At the end of the message, call psa_mac_sign_finish() to finish
 *    calculating the MAC value and retrieve it.
 *
 * The application may call psa_mac_abort() at any time after the operation
 * has been initialized.
 *
 * After a successful call to psa_mac_sign_setup(), the application must
 * eventually terminate the operation through one of the following methods:
 * - A failed call to psa_mac_update().
 * - A call to psa_mac_sign_finish() or psa_mac_abort().
 *
 * \param[in,out] operation The operation object to set up. It must have
 *                          been initialized as per the documentation for
 *                          #psa_mac_operation_t and not yet in use.
 * \param handle            Handle to the key to use for the operation.
 *                          It must remain valid until the operation
 *                          terminates.
 * \param alg               The MAC algorithm to compute (\c PSA_ALG_XXX value
 *                          such that #PSA_ALG_IS_MAC(\p alg) is true).
 *
 * \retval #PSA_SUCCESS
 *         Success.
 * \retval #PSA_ERROR_INVALID_HANDLE
 * \retval #PSA_ERROR_DOES_NOT_EXIST
 * \retval #PSA_ERROR_NOT_PERMITTED
 * \retval #PSA_ERROR_INVALID_ARGUMENT
 *         \p handle is not compatible with \p alg.
 * \retval #PSA_ERROR_NOT_SUPPORTED
 *         \p alg is not supported or is not a MAC algorithm.
 * \retval #PSA_ERROR_INSUFFICIENT_MEMORY
 * \retval #PSA_ERROR_COMMUNICATION_FAILURE
 * \retval #PSA_ERROR_HARDWARE_FAILURE
 * \retval #PSA_ERROR_TAMPERING_DETECTED
 * \retval #PSA_ERROR_BAD_STATE
 *         The operation state is not valid (already set up and not
 *         subsequently completed).
 * \retval #PSA_ERROR_BAD_STATE
 *         The library has not been previously initialized by psa_crypto_init().
 *         It is implementation-dependent whether a failure to initialize
 *         results in this error code.
 */
psa_status_t psa_mac_sign_setup(psa_mac_operation_t *operation,
                                psa_key_handle_t handle,
                                psa_algorithm_t alg);

/** Set up a multipart MAC verification operation.
 *
 * This function sets up the verification of the MAC
 * (message authentication code) of a byte string against an expected value.
 *
 * The sequence of operations to verify a MAC is as follows:
 * -# Allocate an operation object which will be passed to all the functions
 *    listed here.
 * -# Initialize the operation object with one of the methods described in the
 *    documentation for #psa_mac_operation_t, e.g. PSA_MAC_OPERATION_INIT.
 * -# Call psa_mac_verify_setup() to specify the algorithm and key.
 * -# Call psa_mac_update() zero, one or more times, passing a fragment
 *    of the message each time. The MAC that is calculated is the MAC
 *    of the concatenation of these messages in order.
 * -# At the end of the message, call psa_mac_verify_finish() to finish
 *    calculating the actual MAC of the message and verify it against
 *    the expected value.
 *
 * The application may call psa_mac_abort() at any time after the operation
 * has been initialized.
 *
 * After a successful call to psa_mac_verify_setup(), the application must
 * eventually terminate the operation through one of the following methods:
 * - A failed call to psa_mac_update().
 * - A call to psa_mac_verify_finish() or psa_mac_abort().
 *
 * \param[in,out] operation The operation object to set up. It must have
 *                          been initialized as per the documentation for
 *                          #psa_mac_operation_t and not yet in use.
 * \param handle            Handle to the key to use for the operation.
 *                          It must remain valid until the operation
 *                          terminates.
 * \param alg               The MAC algorithm to compute (\c PSA_ALG_XXX value
 *                          such that #PSA_ALG_IS_MAC(\p alg) is true).
 *
 * \retval #PSA_SUCCESS
 *         Success.
 * \retval #PSA_ERROR_INVALID_HANDLE
 * \retval #PSA_ERROR_DOES_NOT_EXIST
 * \retval #PSA_ERROR_NOT_PERMITTED
 * \retval #PSA_ERROR_INVALID_ARGUMENT
 *         \c key is not compatible with \c alg.
 * \retval #PSA_ERROR_NOT_SUPPORTED
 *         \c alg is not supported or is not a MAC algorithm.
 * \retval #PSA_ERROR_INSUFFICIENT_MEMORY
 * \retval #PSA_ERROR_COMMUNICATION_FAILURE
 * \retval #PSA_ERROR_HARDWARE_FAILURE
 * \retval #PSA_ERROR_TAMPERING_DETECTED
 * \retval #PSA_ERROR_BAD_STATE
 *         The operation state is not valid (already set up and not
 *         subsequently completed).
 * \retval #PSA_ERROR_BAD_STATE
 *         The library has not been previously initialized by psa_crypto_init().
 *         It is implementation-dependent whether a failure to initialize
 *         results in this error code.
 */
psa_status_t psa_mac_verify_setup(psa_mac_operation_t *operation,
                                  psa_key_handle_t handle,
                                  psa_algorithm_t alg);

/** Add a message fragment to a multipart MAC operation.
 *
 * The application must call psa_mac_sign_setup() or psa_mac_verify_setup()
 * before calling this function.
 *
 * If this function returns an error status, the operation becomes inactive.
 *
 * \param[in,out] operation Active MAC operation.
 * \param[in] input         Buffer containing the message fragment to add to
 *                          the MAC calculation.
 * \param input_length      Size of the \p input buffer in bytes.
 *
 * \retval #PSA_SUCCESS
 *         Success.
 * \retval #PSA_ERROR_BAD_STATE
 *         The operation state is not valid (not set up, or already completed).
 * \retval #PSA_ERROR_INSUFFICIENT_MEMORY
 * \retval #PSA_ERROR_COMMUNICATION_FAILURE
 * \retval #PSA_ERROR_HARDWARE_FAILURE
 * \retval #PSA_ERROR_TAMPERING_DETECTED
 */
psa_status_t psa_mac_update(psa_mac_operation_t *operation,
                            const uint8_t *input,
                            size_t input_length);

/** Finish the calculation of the MAC of a message.
 *
 * The application must call psa_mac_sign_setup() before calling this function.
 * This function calculates the MAC of the message formed by concatenating
 * the inputs passed to preceding calls to psa_mac_update().
 *
 * When this function returns, the operation becomes inactive.
 *
 * \warning Applications should not call this function if they expect
 *          a specific value for the MAC. Call psa_mac_verify_finish() instead.
 *          Beware that comparing integrity or authenticity data such as
 *          MAC values with a function such as \c memcmp is risky
 *          because the time taken by the comparison may leak information
 *          about the MAC value which could allow an attacker to guess
 *          a valid MAC and thereby bypass security controls.
 *
 * \param[in,out] operation Active MAC operation.
 * \param[out] mac          Buffer where the MAC value is to be written.
 * \param mac_size          Size of the \p mac buffer in bytes.
 * \param[out] mac_length   On success, the number of bytes
 *                          that make up the MAC value. This is always
 *                          #PSA_MAC_FINAL_SIZE(\c key_type, \c key_bits, \c alg)
 *                          where \c key_type and \c key_bits are the type and
 *                          bit-size respectively of the key and \c alg is the
 *                          MAC algorithm that is calculated.
 *
 * \retval #PSA_SUCCESS
 *         Success.
 * \retval #PSA_ERROR_BAD_STATE
 *         The operation state is not valid (not set up, or already completed).
 * \retval #PSA_ERROR_BUFFER_TOO_SMALL
 *         The size of the \p mac buffer is too small. You can determine a
 *         sufficient buffer size by calling PSA_MAC_FINAL_SIZE().
 * \retval #PSA_ERROR_INSUFFICIENT_MEMORY
 * \retval #PSA_ERROR_COMMUNICATION_FAILURE
 * \retval #PSA_ERROR_HARDWARE_FAILURE
 * \retval #PSA_ERROR_TAMPERING_DETECTED
 */
psa_status_t psa_mac_sign_finish(psa_mac_operation_t *operation,
                                 uint8_t *mac,
                                 size_t mac_size,
                                 size_t *mac_length);

/** Finish the calculation of the MAC of a message and compare it with
 * an expected value.
 *
 * The application must call psa_mac_verify_setup() before calling this function.
 * This function calculates the MAC of the message formed by concatenating
 * the inputs passed to preceding calls to psa_mac_update(). It then
 * compares the calculated MAC with the expected MAC passed as a
 * parameter to this function.
 *
 * When this function returns, the operation becomes inactive.
 *
 * \note Implementations shall make the best effort to ensure that the
 * comparison between the actual MAC and the expected MAC is performed
 * in constant time.
 *
 * \param[in,out] operation Active MAC operation.
 * \param[in] mac           Buffer containing the expected MAC value.
 * \param mac_length        Size of the \p mac buffer in bytes.
 *
 * \retval #PSA_SUCCESS
 *         The expected MAC is identical to the actual MAC of the message.
 * \retval #PSA_ERROR_INVALID_SIGNATURE
 *         The MAC of the message was calculated successfully, but it
 *         differs from the expected MAC.
 * \retval #PSA_ERROR_BAD_STATE
 *         The operation state is not valid (not set up, or already completed).
 * \retval #PSA_ERROR_INSUFFICIENT_MEMORY
 * \retval #PSA_ERROR_COMMUNICATION_FAILURE
 * \retval #PSA_ERROR_HARDWARE_FAILURE
 * \retval #PSA_ERROR_TAMPERING_DETECTED
 */
psa_status_t psa_mac_verify_finish(psa_mac_operation_t *operation,
                                   const uint8_t *mac,
                                   size_t mac_length);

/** Abort a MAC operation.
 *
 * Aborting an operation frees all associated resources except for the
 * \p operation structure itself. Once aborted, the operation object
 * can be reused for another operation by calling
 * psa_mac_sign_setup() or psa_mac_verify_setup() again.
 *
 * You may call this function any time after the operation object has
 * been initialized by any of the following methods:
 * - A call to psa_mac_sign_setup() or psa_mac_verify_setup(), whether
 *   it succeeds or not.
 * - Initializing the \c struct to all-bits-zero.
 * - Initializing the \c struct to logical zeros, e.g.
 *   `psa_mac_operation_t operation = {0}`.
 *
 * In particular, calling psa_mac_abort() after the operation has been
 * terminated by a call to psa_mac_abort(), psa_mac_sign_finish() or
 * psa_mac_verify_finish() is safe and has no effect.
 *
 * \param[in,out] operation Initialized MAC operation.
 *
 * \retval #PSA_SUCCESS
 * \retval #PSA_ERROR_BAD_STATE
 *         \p operation is not an active MAC operation.
 * \retval #PSA_ERROR_COMMUNICATION_FAILURE
 * \retval #PSA_ERROR_HARDWARE_FAILURE
 * \retval #PSA_ERROR_TAMPERING_DETECTED
 */
psa_status_t psa_mac_abort(psa_mac_operation_t *operation);

/**@}*/

/** \defgroup cipher Symmetric ciphers
 * @{
 */

/** Encrypt a message using a symmetric cipher.
 *
 * This function encrypts a message with a random IV (initialization
 * vector).
 *
 * \param handle                Handle to the key to use for the operation.
 *                              It must remain valid until the operation
 *                              terminates.
 * \param alg                   The cipher algorithm to compute
 *                              (\c PSA_ALG_XXX value such that
 *                              #PSA_ALG_IS_CIPHER(\p alg) is true).
 * \param[in] input             Buffer containing the message to encrypt.
 * \param input_length          Size of the \p input buffer in bytes.
 * \param[out] output           Buffer where the output is to be written.
 *                              The output contains the IV followed by
 *                              the ciphertext proper.
 * \param output_size           Size of the \p output buffer in bytes.
 * \param[out] output_length    On success, the number of bytes
 *                              that make up the output.
 *
 * \retval #PSA_SUCCESS
 *         Success.
 * \retval #PSA_ERROR_INVALID_HANDLE
 * \retval #PSA_ERROR_EMPTY_SLOT
 * \retval #PSA_ERROR_NOT_PERMITTED
 * \retval #PSA_ERROR_INVALID_ARGUMENT
 *         \p handle is not compatible with \p alg.
 * \retval #PSA_ERROR_NOT_SUPPORTED
 *         \p alg is not supported or is not a cipher algorithm.
 * \retval #PSA_ERROR_BUFFER_TOO_SMALL
 * \retval #PSA_ERROR_INSUFFICIENT_MEMORY
 * \retval #PSA_ERROR_COMMUNICATION_FAILURE
 * \retval #PSA_ERROR_HARDWARE_FAILURE
 * \retval #PSA_ERROR_TAMPERING_DETECTED
 */
psa_status_t psa_cipher_encrypt(psa_key_handle_t handle,
                                psa_algorithm_t alg,
                                const uint8_t *input,
                                size_t input_length,
                                uint8_t *output,
                                size_t output_size,
                                size_t *output_length);

/** Decrypt a message using a symmetric cipher.
 *
 * This function decrypts a message encrypted with a symmetric cipher.
 *
 * \param handle                Handle to the key to use for the operation.
 *                              It must remain valid until the operation
 *                              terminates.
 * \param alg                   The cipher algorithm to compute
 *                              (\c PSA_ALG_XXX value such that
 *                              #PSA_ALG_IS_CIPHER(\p alg) is true).
 * \param[in] input             Buffer containing the message to decrypt.
 *                              This consists of the IV followed by the
 *                              ciphertext proper.
 * \param input_length          Size of the \p input buffer in bytes.
 * \param[out] output           Buffer where the plaintext is to be written.
 * \param output_size           Size of the \p output buffer in bytes.
 * \param[out] output_length    On success, the number of bytes
 *                              that make up the output.
 *
 * \retval #PSA_SUCCESS
 *         Success.
 * \retval #PSA_ERROR_INVALID_HANDLE
 * \retval #PSA_ERROR_EMPTY_SLOT
 * \retval #PSA_ERROR_NOT_PERMITTED
 * \retval #PSA_ERROR_INVALID_ARGUMENT
 *         \p handle is not compatible with \p alg.
 * \retval #PSA_ERROR_NOT_SUPPORTED
 *         \p alg is not supported or is not a cipher algorithm.
 * \retval #PSA_ERROR_BUFFER_TOO_SMALL
 * \retval #PSA_ERROR_INSUFFICIENT_MEMORY
 * \retval #PSA_ERROR_COMMUNICATION_FAILURE
 * \retval #PSA_ERROR_HARDWARE_FAILURE
 * \retval #PSA_ERROR_TAMPERING_DETECTED
 */
psa_status_t psa_cipher_decrypt(psa_key_handle_t handle,
                                psa_algorithm_t alg,
                                const uint8_t *input,
                                size_t input_length,
                                uint8_t *output,
                                size_t output_size,
                                size_t *output_length);

/** The type of the state data structure for multipart cipher operations.
 *
 * Before calling any function on a cipher operation object, the application
 * must initialize it by any of the following means:
 * - Set the structure to all-bits-zero, for example:
 *   \code
 *   psa_cipher_operation_t operation;
 *   memset(&operation, 0, sizeof(operation));
 *   \endcode
 * - Initialize the structure to logical zero values, for example:
 *   \code
 *   psa_cipher_operation_t operation = {0};
 *   \endcode
 * - Initialize the structure to the initializer #PSA_CIPHER_OPERATION_INIT,
 *   for example:
 *   \code
 *   psa_cipher_operation_t operation = PSA_CIPHER_OPERATION_INIT;
 *   \endcode
 * - Assign the result of the function psa_cipher_operation_init()
 *   to the structure, for example:
 *   \code
 *   psa_cipher_operation_t operation;
 *   operation = psa_cipher_operation_init();
 *   \endcode
 *
 * This is an implementation-defined \c struct. Applications should not
 * make any assumptions about the content of this structure except
 * as directed by the documentation of a specific implementation. */
typedef struct psa_cipher_operation_s psa_cipher_operation_t;

/** \def PSA_CIPHER_OPERATION_INIT
 *
 * This macro returns a suitable initializer for a cipher operation object of
 * type #psa_cipher_operation_t.
 */
#ifdef __DOXYGEN_ONLY__
/* This is an example definition for documentation purposes.
 * Implementations should define a suitable value in `crypto_struct.h`.
 */
#define PSA_CIPHER_OPERATION_INIT {0}
#endif

/** Return an initial value for a cipher operation object.
 */
static psa_cipher_operation_t psa_cipher_operation_init(void);

/** Set the key for a multipart symmetric encryption operation.
 *
 * The sequence of operations to encrypt a message with a symmetric cipher
 * is as follows:
 * -# Allocate an operation object which will be passed to all the functions
 *    listed here.
 * -# Initialize the operation object with one of the methods described in the
 *    documentation for #psa_cipher_operation_t, e.g.
 *    PSA_CIPHER_OPERATION_INIT.
 * -# Call psa_cipher_encrypt_setup() to specify the algorithm and key.
 * -# Call either psa_cipher_generate_iv() or psa_cipher_set_iv() to
 *    generate or set the IV (initialization vector). You should use
 *    psa_cipher_generate_iv() unless the protocol you are implementing
 *    requires a specific IV value.
 * -# Call psa_cipher_update() zero, one or more times, passing a fragment
 *    of the message each time.
 * -# Call psa_cipher_finish().
 *
 * The application may call psa_cipher_abort() at any time after the operation
 * has been initialized.
 *
 * After a successful call to psa_cipher_encrypt_setup(), the application must
 * eventually terminate the operation. The following events terminate an
 * operation:
 * - A failed call to any of the \c psa_cipher_xxx functions.
 * - A call to psa_cipher_finish() or psa_cipher_abort().
 *
 * \param[in,out] operation     The operation object to set up. It must have
 *                              been initialized as per the documentation for
 *                              #psa_cipher_operation_t and not yet in use.
 * \param handle                Handle to the key to use for the operation.
 *                              It must remain valid until the operation
 *                              terminates.
 * \param alg                   The cipher algorithm to compute
 *                              (\c PSA_ALG_XXX value such that
 *                              #PSA_ALG_IS_CIPHER(\p alg) is true).
 *
 * \retval #PSA_SUCCESS
 *         Success.
 * \retval #PSA_ERROR_INVALID_HANDLE
 * \retval #PSA_ERROR_DOES_NOT_EXIST
 * \retval #PSA_ERROR_NOT_PERMITTED
 * \retval #PSA_ERROR_INVALID_ARGUMENT
 *         \p handle is not compatible with \p alg.
 * \retval #PSA_ERROR_NOT_SUPPORTED
 *         \p alg is not supported or is not a cipher algorithm.
 * \retval #PSA_ERROR_INSUFFICIENT_MEMORY
 * \retval #PSA_ERROR_COMMUNICATION_FAILURE
 * \retval #PSA_ERROR_HARDWARE_FAILURE
 * \retval #PSA_ERROR_TAMPERING_DETECTED
 * \retval #PSA_ERROR_BAD_STATE
 *         The operation state is not valid (already set up and not
 *         subsequently completed).
 * \retval #PSA_ERROR_BAD_STATE
 *         The library has not been previously initialized by psa_crypto_init().
 *         It is implementation-dependent whether a failure to initialize
 *         results in this error code.
 */
psa_status_t psa_cipher_encrypt_setup(psa_cipher_operation_t *operation,
                                      psa_key_handle_t handle,
                                      psa_algorithm_t alg);

/** Set the key for a multipart symmetric decryption operation.
 *
 * The sequence of operations to decrypt a message with a symmetric cipher
 * is as follows:
 * -# Allocate an operation object which will be passed to all the functions
 *    listed here.
 * -# Initialize the operation object with one of the methods described in the
 *    documentation for #psa_cipher_operation_t, e.g.
 *    PSA_CIPHER_OPERATION_INIT.
 * -# Call psa_cipher_decrypt_setup() to specify the algorithm and key.
 * -# Call psa_cipher_set_iv() with the IV (initialization vector) for the
 *    decryption. If the IV is prepended to the ciphertext, you can call
 *    psa_cipher_update() on a buffer containing the IV followed by the
 *    beginning of the message.
 * -# Call psa_cipher_update() zero, one or more times, passing a fragment
 *    of the message each time.
 * -# Call psa_cipher_finish().
 *
 * The application may call psa_cipher_abort() at any time after the operation
 * has been initialized.
 *
 * After a successful call to psa_cipher_decrypt_setup(), the application must
 * eventually terminate the operation. The following events terminate an
 * operation:
 * - A failed call to any of the \c psa_cipher_xxx functions.
 * - A call to psa_cipher_finish() or psa_cipher_abort().
 *
 * \param[in,out] operation     The operation object to set up. It must have
 *                              been initialized as per the documentation for
 *                              #psa_cipher_operation_t and not yet in use.
 * \param handle                Handle to the key to use for the operation.
 *                              It must remain valid until the operation
 *                              terminates.
 * \param alg                   The cipher algorithm to compute
 *                              (\c PSA_ALG_XXX value such that
 *                              #PSA_ALG_IS_CIPHER(\p alg) is true).
 *
 * \retval #PSA_SUCCESS
 *         Success.
 * \retval #PSA_ERROR_INVALID_HANDLE
 * \retval #PSA_ERROR_DOES_NOT_EXIST
 * \retval #PSA_ERROR_NOT_PERMITTED
 * \retval #PSA_ERROR_INVALID_ARGUMENT
 *         \p handle is not compatible with \p alg.
 * \retval #PSA_ERROR_NOT_SUPPORTED
 *         \p alg is not supported or is not a cipher algorithm.
 * \retval #PSA_ERROR_INSUFFICIENT_MEMORY
 * \retval #PSA_ERROR_COMMUNICATION_FAILURE
 * \retval #PSA_ERROR_HARDWARE_FAILURE
 * \retval #PSA_ERROR_TAMPERING_DETECTED
 * \retval #PSA_ERROR_BAD_STATE
 *         The operation state is not valid (already set up and not
 *         subsequently completed).
 * \retval #PSA_ERROR_BAD_STATE
 *         The library has not been previously initialized by psa_crypto_init().
 *         It is implementation-dependent whether a failure to initialize
 *         results in this error code.
 */
psa_status_t psa_cipher_decrypt_setup(psa_cipher_operation_t *operation,
                                      psa_key_handle_t handle,
                                      psa_algorithm_t alg);

/** Generate an IV for a symmetric encryption operation.
 *
 * This function generates a random IV (initialization vector), nonce
 * or initial counter value for the encryption operation as appropriate
 * for the chosen algorithm, key type and key size.
 *
 * The application must call psa_cipher_encrypt_setup() before
 * calling this function.
 *
 * If this function returns an error status, the operation becomes inactive.
 *
 * \param[in,out] operation     Active cipher operation.
 * \param[out] iv               Buffer where the generated IV is to be written.
 * \param iv_size               Size of the \p iv buffer in bytes.
 * \param[out] iv_length        On success, the number of bytes of the
 *                              generated IV.
 *
 * \retval #PSA_SUCCESS
 *         Success.
 * \retval #PSA_ERROR_BAD_STATE
 *         The operation state is not valid (not set up, or IV already set).
 * \retval #PSA_ERROR_BUFFER_TOO_SMALL
 *         The size of the \p iv buffer is too small.
 * \retval #PSA_ERROR_INSUFFICIENT_MEMORY
 * \retval #PSA_ERROR_COMMUNICATION_FAILURE
 * \retval #PSA_ERROR_HARDWARE_FAILURE
 * \retval #PSA_ERROR_TAMPERING_DETECTED
 */
psa_status_t psa_cipher_generate_iv(psa_cipher_operation_t *operation,
                                    unsigned char *iv,
                                    size_t iv_size,
                                    size_t *iv_length);

/** Set the IV for a symmetric encryption or decryption operation.
 *
 * This function sets the IV (initialization vector), nonce
 * or initial counter value for the encryption or decryption operation.
 *
 * The application must call psa_cipher_encrypt_setup() before
 * calling this function.
 *
 * If this function returns an error status, the operation becomes inactive.
 *
 * \note When encrypting, applications should use psa_cipher_generate_iv()
 * instead of this function, unless implementing a protocol that requires
 * a non-random IV.
 *
 * \param[in,out] operation     Active cipher operation.
 * \param[in] iv                Buffer containing the IV to use.
 * \param iv_length             Size of the IV in bytes.
 *
 * \retval #PSA_SUCCESS
 *         Success.
 * \retval #PSA_ERROR_BAD_STATE
 *         The operation state is not valid (not set up, or IV already set).
 * \retval #PSA_ERROR_INVALID_ARGUMENT
 *         The size of \p iv is not acceptable for the chosen algorithm,
 *         or the chosen algorithm does not use an IV.
 * \retval #PSA_ERROR_INSUFFICIENT_MEMORY
 * \retval #PSA_ERROR_COMMUNICATION_FAILURE
 * \retval #PSA_ERROR_HARDWARE_FAILURE
 * \retval #PSA_ERROR_TAMPERING_DETECTED
 */
psa_status_t psa_cipher_set_iv(psa_cipher_operation_t *operation,
                               const unsigned char *iv,
                               size_t iv_length);

/** Encrypt or decrypt a message fragment in an active cipher operation.
 *
 * Before calling this function, you must:
 * 1. Call either psa_cipher_encrypt_setup() or psa_cipher_decrypt_setup().
 *    The choice of setup function determines whether this function
 *    encrypts or decrypts its input.
 * 2. If the algorithm requires an IV, call psa_cipher_generate_iv()
 *    (recommended when encrypting) or psa_cipher_set_iv().
 *
 * If this function returns an error status, the operation becomes inactive.
 *
 * \param[in,out] operation     Active cipher operation.
 * \param[in] input             Buffer containing the message fragment to
 *                              encrypt or decrypt.
 * \param input_length          Size of the \p input buffer in bytes.
 * \param[out] output           Buffer where the output is to be written.
 * \param output_size           Size of the \p output buffer in bytes.
 * \param[out] output_length    On success, the number of bytes
 *                              that make up the returned output.
 *
 * \retval #PSA_SUCCESS
 *         Success.
 * \retval #PSA_ERROR_BAD_STATE
 *         The operation state is not valid (not set up, IV required but
 *         not set, or already completed).
 * \retval #PSA_ERROR_BUFFER_TOO_SMALL
 *         The size of the \p output buffer is too small.
 * \retval #PSA_ERROR_INSUFFICIENT_MEMORY
 * \retval #PSA_ERROR_COMMUNICATION_FAILURE
 * \retval #PSA_ERROR_HARDWARE_FAILURE
 * \retval #PSA_ERROR_TAMPERING_DETECTED
 */
psa_status_t psa_cipher_update(psa_cipher_operation_t *operation,
                               const uint8_t *input,
                               size_t input_length,
                               unsigned char *output,
                               size_t output_size,
                               size_t *output_length);

/** Finish encrypting or decrypting a message in a cipher operation.
 *
 * The application must call psa_cipher_encrypt_setup() or
 * psa_cipher_decrypt_setup() before calling this function. The choice
 * of setup function determines whether this function encrypts or
 * decrypts its input.
 *
 * This function finishes the encryption or decryption of the message
 * formed by concatenating the inputs passed to preceding calls to
 * psa_cipher_update().
 *
 * When this function returns, the operation becomes inactive.
 *
 * \param[in,out] operation     Active cipher operation.
 * \param[out] output           Buffer where the output is to be written.
 * \param output_size           Size of the \p output buffer in bytes.
 * \param[out] output_length    On success, the number of bytes
 *                              that make up the returned output.
 *
 * \retval #PSA_SUCCESS
 *         Success.
 * \retval #PSA_ERROR_BAD_STATE
 *         The operation state is not valid (not set up, IV required but
 *         not set, or already completed).
 * \retval #PSA_ERROR_BUFFER_TOO_SMALL
 *         The size of the \p output buffer is too small.
 * \retval #PSA_ERROR_INSUFFICIENT_MEMORY
 * \retval #PSA_ERROR_COMMUNICATION_FAILURE
 * \retval #PSA_ERROR_HARDWARE_FAILURE
 * \retval #PSA_ERROR_TAMPERING_DETECTED
 */
psa_status_t psa_cipher_finish(psa_cipher_operation_t *operation,
                               uint8_t *output,
                               size_t output_size,
                               size_t *output_length);

/** Abort a cipher operation.
 *
 * Aborting an operation frees all associated resources except for the
 * \p operation structure itself. Once aborted, the operation object
 * can be reused for another operation by calling
 * psa_cipher_encrypt_setup() or psa_cipher_decrypt_setup() again.
 *
 * You may call this function any time after the operation object has
 * been initialized by any of the following methods:
 * - A call to psa_cipher_encrypt_setup() or psa_cipher_decrypt_setup(),
 *   whether it succeeds or not.
 * - Initializing the \c struct to all-bits-zero.
 * - Initializing the \c struct to logical zeros, e.g.
 *   `psa_cipher_operation_t operation = {0}`.
 *
 * In particular, calling psa_cipher_abort() after the operation has been
 * terminated by a call to psa_cipher_abort() or psa_cipher_finish()
 * is safe and has no effect.
 *
 * \param[in,out] operation     Initialized cipher operation.
 *
 * \retval #PSA_SUCCESS
 * \retval #PSA_ERROR_BAD_STATE
 *         \p operation is not an active cipher operation.
 * \retval #PSA_ERROR_COMMUNICATION_FAILURE
 * \retval #PSA_ERROR_HARDWARE_FAILURE
 * \retval #PSA_ERROR_TAMPERING_DETECTED
 */
psa_status_t psa_cipher_abort(psa_cipher_operation_t *operation);

/**@}*/

/** \defgroup aead Authenticated encryption with associated data (AEAD)
 * @{
 */

/** Process an authenticated encryption operation.
 *
 * \param handle                  Handle to the key to use for the operation.
 * \param alg                     The AEAD algorithm to compute
 *                                (\c PSA_ALG_XXX value such that
 *                                #PSA_ALG_IS_AEAD(\p alg) is true).
 * \param[in] nonce               Nonce or IV to use.
 * \param nonce_length            Size of the \p nonce buffer in bytes.
 * \param[in] additional_data     Additional data that will be authenticated
 *                                but not encrypted.
 * \param additional_data_length  Size of \p additional_data in bytes.
 * \param[in] plaintext           Data that will be authenticated and
 *                                encrypted.
 * \param plaintext_length        Size of \p plaintext in bytes.
 * \param[out] ciphertext         Output buffer for the authenticated and
 *                                encrypted data. The additional data is not
 *                                part of this output. For algorithms where the
 *                                encrypted data and the authentication tag
 *                                are defined as separate outputs, the
 *                                authentication tag is appended to the
 *                                encrypted data.
 * \param ciphertext_size         Size of the \p ciphertext buffer in bytes.
 *                                This must be at least
 *                                #PSA_AEAD_ENCRYPT_OUTPUT_SIZE(\p alg,
 *                                \p plaintext_length).
 * \param[out] ciphertext_length  On success, the size of the output
 *                                in the \p ciphertext buffer.
 *
 * \retval #PSA_SUCCESS
 *         Success.
 * \retval #PSA_ERROR_INVALID_HANDLE
 * \retval #PSA_ERROR_DOES_NOT_EXIST
 * \retval #PSA_ERROR_NOT_PERMITTED
 * \retval #PSA_ERROR_INVALID_ARGUMENT
 *         \p handle is not compatible with \p alg.
 * \retval #PSA_ERROR_NOT_SUPPORTED
 *         \p alg is not supported or is not an AEAD algorithm.
 * \retval #PSA_ERROR_INSUFFICIENT_MEMORY
 * \retval #PSA_ERROR_COMMUNICATION_FAILURE
 * \retval #PSA_ERROR_HARDWARE_FAILURE
 * \retval #PSA_ERROR_TAMPERING_DETECTED
 * \retval #PSA_ERROR_BAD_STATE
 *         The library has not been previously initialized by psa_crypto_init().
 *         It is implementation-dependent whether a failure to initialize
 *         results in this error code.
 */
psa_status_t psa_aead_encrypt(psa_key_handle_t handle,
                              psa_algorithm_t alg,
                              const uint8_t *nonce,
                              size_t nonce_length,
                              const uint8_t *additional_data,
                              size_t additional_data_length,
                              const uint8_t *plaintext,
                              size_t plaintext_length,
                              uint8_t *ciphertext,
                              size_t ciphertext_size,
                              size_t *ciphertext_length);

/** Process an authenticated decryption operation.
 *
 * \param handle                  Handle to the key to use for the operation.
 * \param alg                     The AEAD algorithm to compute
 *                                (\c PSA_ALG_XXX value such that
 *                                #PSA_ALG_IS_AEAD(\p alg) is true).
 * \param[in] nonce               Nonce or IV to use.
 * \param nonce_length            Size of the \p nonce buffer in bytes.
 * \param[in] additional_data     Additional data that has been authenticated
 *                                but not encrypted.
 * \param additional_data_length  Size of \p additional_data in bytes.
 * \param[in] ciphertext          Data that has been authenticated and
 *                                encrypted. For algorithms where the
 *                                encrypted data and the authentication tag
 *                                are defined as separate inputs, the buffer
 *                                must contain the encrypted data followed
 *                                by the authentication tag.
 * \param ciphertext_length       Size of \p ciphertext in bytes.
 * \param[out] plaintext          Output buffer for the decrypted data.
 * \param plaintext_size          Size of the \p plaintext buffer in bytes.
 *                                This must be at least
 *                                #PSA_AEAD_DECRYPT_OUTPUT_SIZE(\p alg,
 *                                \p ciphertext_length).
 * \param[out] plaintext_length   On success, the size of the output
 *                                in the \p plaintext buffer.
 *
 * \retval #PSA_SUCCESS
 *         Success.
 * \retval #PSA_ERROR_INVALID_HANDLE
 * \retval #PSA_ERROR_DOES_NOT_EXIST
 * \retval #PSA_ERROR_INVALID_SIGNATURE
 *         The ciphertext is not authentic.
 * \retval #PSA_ERROR_NOT_PERMITTED
 * \retval #PSA_ERROR_INVALID_ARGUMENT
 *         \p handle is not compatible with \p alg.
 * \retval #PSA_ERROR_NOT_SUPPORTED
 *         \p alg is not supported or is not an AEAD algorithm.
 * \retval #PSA_ERROR_INSUFFICIENT_MEMORY
 * \retval #PSA_ERROR_COMMUNICATION_FAILURE
 * \retval #PSA_ERROR_HARDWARE_FAILURE
 * \retval #PSA_ERROR_TAMPERING_DETECTED
 * \retval #PSA_ERROR_BAD_STATE
 *         The library has not been previously initialized by psa_crypto_init().
 *         It is implementation-dependent whether a failure to initialize
 *         results in this error code.
 */
psa_status_t psa_aead_decrypt(psa_key_handle_t handle,
                              psa_algorithm_t alg,
                              const uint8_t *nonce,
                              size_t nonce_length,
                              const uint8_t *additional_data,
                              size_t additional_data_length,
                              const uint8_t *ciphertext,
                              size_t ciphertext_length,
                              uint8_t *plaintext,
                              size_t plaintext_size,
                              size_t *plaintext_length);

/** The type of the state data structure for multipart AEAD operations.
 *
 * Before calling any function on an AEAD operation object, the application
 * must initialize it by any of the following means:
 * - Set the structure to all-bits-zero, for example:
 *   \code
 *   psa_aead_operation_t operation;
 *   memset(&operation, 0, sizeof(operation));
 *   \endcode
 * - Initialize the structure to logical zero values, for example:
 *   \code
 *   psa_aead_operation_t operation = {0};
 *   \endcode
 * - Initialize the structure to the initializer #PSA_AEAD_OPERATION_INIT,
 *   for example:
 *   \code
 *   psa_aead_operation_t operation = PSA_AEAD_OPERATION_INIT;
 *   \endcode
 * - Assign the result of the function psa_aead_operation_init()
 *   to the structure, for example:
 *   \code
 *   psa_aead_operation_t operation;
 *   operation = psa_aead_operation_init();
 *   \endcode
 *
 * This is an implementation-defined \c struct. Applications should not
 * make any assumptions about the content of this structure except
 * as directed by the documentation of a specific implementation. */
typedef struct psa_aead_operation_s psa_aead_operation_t;

/** \def PSA_AEAD_OPERATION_INIT
 *
 * This macro returns a suitable initializer for an AEAD operation object of
 * type #psa_aead_operation_t.
 */
#ifdef __DOXYGEN_ONLY__
/* This is an example definition for documentation purposes.
 * Implementations should define a suitable value in `crypto_struct.h`.
 */
#define PSA_AEAD_OPERATION_INIT {0}
#endif

/** Return an initial value for an AEAD operation object.
 */
static psa_aead_operation_t psa_aead_operation_init(void);

/** Set the key for a multipart authenticated encryption operation.
 *
 * The sequence of operations to encrypt a message with authentication
 * is as follows:
 * -# Allocate an operation object which will be passed to all the functions
 *    listed here.
 * -# Initialize the operation object with one of the methods described in the
 *    documentation for #psa_aead_operation_t, e.g.
 *    PSA_AEAD_OPERATION_INIT.
 * -# Call psa_aead_encrypt_setup() to specify the algorithm and key.
 * -# If needed, call psa_aead_set_lengths() to specify the length of the
 *    inputs to the subsequent calls to psa_aead_update_ad() and
 *    psa_aead_update(). See the documentation of psa_aead_set_lengths()
 *    for details.
 * -# Call either psa_aead_generate_nonce() or psa_aead_set_nonce() to
 *    generate or set the nonce. You should use
 *    psa_aead_generate_nonce() unless the protocol you are implementing
 *    requires a specific nonce value.
 * -# Call psa_aead_update_ad() zero, one or more times, passing a fragment
 *    of the non-encrypted additional authenticated data each time.
 * -# Call psa_aead_update() zero, one or more times, passing a fragment
 *    of the message to encrypt each time.
 * -# Call psa_aead_finish().
 *
 * The application may call psa_aead_abort() at any time after the operation
 * has been initialized.
 *
 * After a successful call to psa_aead_encrypt_setup(), the application must
 * eventually terminate the operation. The following events terminate an
 * operation:
 * - A failed call to any of the \c psa_aead_xxx functions.
 * - A call to psa_aead_finish(), psa_aead_verify() or psa_aead_abort().
 *
 * \param[in,out] operation     The operation object to set up. It must have
 *                              been initialized as per the documentation for
 *                              #psa_aead_operation_t and not yet in use.
 * \param handle                Handle to the key to use for the operation.
 *                              It must remain valid until the operation
 *                              terminates.
 * \param alg                   The AEAD algorithm to compute
 *                              (\c PSA_ALG_XXX value such that
 *                              #PSA_ALG_IS_AEAD(\p alg) is true).
 *
 * \retval #PSA_SUCCESS
 *         Success.
 * \retval #PSA_ERROR_INVALID_HANDLE
 * \retval #PSA_ERROR_EMPTY_SLOT
 * \retval #PSA_ERROR_NOT_PERMITTED
 * \retval #PSA_ERROR_INVALID_ARGUMENT
 *         \p handle is not compatible with \p alg.
 * \retval #PSA_ERROR_NOT_SUPPORTED
 *         \p alg is not supported or is not an AEAD algorithm.
 * \retval #PSA_ERROR_INSUFFICIENT_MEMORY
 * \retval #PSA_ERROR_COMMUNICATION_FAILURE
 * \retval #PSA_ERROR_HARDWARE_FAILURE
 * \retval #PSA_ERROR_TAMPERING_DETECTED
 * \retval #PSA_ERROR_BAD_STATE
 *         The library has not been previously initialized by psa_crypto_init().
 *         It is implementation-dependent whether a failure to initialize
 *         results in this error code.
 */
psa_status_t psa_aead_encrypt_setup(psa_aead_operation_t *operation,
                                    psa_key_handle_t handle,
                                    psa_algorithm_t alg);

/** Set the key for a multipart authenticated decryption operation.
 *
 * The sequence of operations to decrypt a message with authentication
 * is as follows:
 * -# Allocate an operation object which will be passed to all the functions
 *    listed here.
 * -# Initialize the operation object with one of the methods described in the
 *    documentation for #psa_aead_operation_t, e.g.
 *    PSA_AEAD_OPERATION_INIT.
 * -# Call psa_aead_decrypt_setup() to specify the algorithm and key.
 * -# If needed, call psa_aead_set_lengths() to specify the length of the
 *    inputs to the subsequent calls to psa_aead_update_ad() and
 *    psa_aead_update(). See the documentation of psa_aead_set_lengths()
 *    for details.
 * -# Call psa_aead_set_nonce() with the nonce for the decryption.
 * -# Call psa_aead_update_ad() zero, one or more times, passing a fragment
 *    of the non-encrypted additional authenticated data each time.
 * -# Call psa_aead_update() zero, one or more times, passing a fragment
 *    of the ciphertext to decrypt each time.
 * -# Call psa_aead_verify().
 *
 * The application may call psa_aead_abort() at any time after the operation
 * has been initialized.
 *
 * After a successful call to psa_aead_decrypt_setup(), the application must
 * eventually terminate the operation. The following events terminate an
 * operation:
 * - A failed call to any of the \c psa_aead_xxx functions.
 * - A call to psa_aead_finish(), psa_aead_verify() or psa_aead_abort().
 *
 * \param[in,out] operation     The operation object to set up. It must have
 *                              been initialized as per the documentation for
 *                              #psa_aead_operation_t and not yet in use.
 * \param handle                Handle to the key to use for the operation.
 *                              It must remain valid until the operation
 *                              terminates.
 * \param alg                   The AEAD algorithm to compute
 *                              (\c PSA_ALG_XXX value such that
 *                              #PSA_ALG_IS_AEAD(\p alg) is true).
 *
 * \retval #PSA_SUCCESS
 *         Success.
 * \retval #PSA_ERROR_INVALID_HANDLE
 * \retval #PSA_ERROR_EMPTY_SLOT
 * \retval #PSA_ERROR_NOT_PERMITTED
 * \retval #PSA_ERROR_INVALID_ARGUMENT
 *         \p handle is not compatible with \p alg.
 * \retval #PSA_ERROR_NOT_SUPPORTED
 *         \p alg is not supported or is not an AEAD algorithm.
 * \retval #PSA_ERROR_INSUFFICIENT_MEMORY
 * \retval #PSA_ERROR_COMMUNICATION_FAILURE
 * \retval #PSA_ERROR_HARDWARE_FAILURE
 * \retval #PSA_ERROR_TAMPERING_DETECTED
 * \retval #PSA_ERROR_BAD_STATE
 *         The library has not been previously initialized by psa_crypto_init().
 *         It is implementation-dependent whether a failure to initialize
 *         results in this error code.
 */
psa_status_t psa_aead_decrypt_setup(psa_aead_operation_t *operation,
                                    psa_key_handle_t handle,
                                    psa_algorithm_t alg);

/** Generate a random nonce for an authenticated encryption operation.
 *
 * This function generates a random nonce for the authenticated encryption
 * operation with an appropriate size for the chosen algorithm, key type
 * and key size.
 *
 * The application must call psa_aead_encrypt_setup() before
 * calling this function.
 *
 * If this function returns an error status, the operation becomes inactive.
 *
 * \param[in,out] operation     Active AEAD operation.
 * \param[out] nonce            Buffer where the generated nonce is to be
 *                              written.
 * \param nonce_size            Size of the \p nonce buffer in bytes.
 * \param[out] nonce_length     On success, the number of bytes of the
 *                              generated nonce.
 *
 * \retval #PSA_SUCCESS
 *         Success.
 * \retval #PSA_ERROR_BAD_STATE
 *         The operation state is not valid (not set up, or nonce already set).
 * \retval #PSA_ERROR_BUFFER_TOO_SMALL
 *         The size of the \p nonce buffer is too small.
 * \retval #PSA_ERROR_INSUFFICIENT_MEMORY
 * \retval #PSA_ERROR_COMMUNICATION_FAILURE
 * \retval #PSA_ERROR_HARDWARE_FAILURE
 * \retval #PSA_ERROR_TAMPERING_DETECTED
 */
psa_status_t psa_aead_generate_nonce(psa_aead_operation_t *operation,
                                     unsigned char *nonce,
                                     size_t nonce_size,
                                     size_t *nonce_length);

/** Set the nonce for an authenticated encryption or decryption operation.
 *
 * This function sets the nonce for the authenticated
 * encryption or decryption operation.
 *
 * The application must call psa_aead_encrypt_setup() before
 * calling this function.
 *
 * If this function returns an error status, the operation becomes inactive.
 *
 * \note When encrypting, applications should use psa_aead_generate_nonce()
 * instead of this function, unless implementing a protocol that requires
 * a non-random IV.
 *
 * \param[in,out] operation     Active AEAD operation.
 * \param[in] nonce             Buffer containing the nonce to use.
 * \param nonce_length          Size of the nonce in bytes.
 *
 * \retval #PSA_SUCCESS
 *         Success.
 * \retval #PSA_ERROR_BAD_STATE
 *         The operation state is not valid (not set up, or nonce already set).
 * \retval #PSA_ERROR_INVALID_ARGUMENT
 *         The size of \p nonce is not acceptable for the chosen algorithm.
 * \retval #PSA_ERROR_INSUFFICIENT_MEMORY
 * \retval #PSA_ERROR_COMMUNICATION_FAILURE
 * \retval #PSA_ERROR_HARDWARE_FAILURE
 * \retval #PSA_ERROR_TAMPERING_DETECTED
 */
psa_status_t psa_aead_set_nonce(psa_aead_operation_t *operation,
                                const unsigned char *nonce,
                                size_t nonce_length);

/** Declare the lengths of the message and additional data for AEAD.
 *
 * The application must call this function before calling
 * psa_aead_update_ad() or psa_aead_update() if the algorithm for
 * the operation requires it. If the algorithm does not require it,
 * calling this function is optional, but if this function is called
 * then the implementation must enforce the lengths.
 *
 * You may call this function before or after setting the nonce with
 * psa_aead_set_nonce() or psa_aead_generate_nonce().
 *
 * - For #PSA_ALG_CCM, calling this function is required.
 * - For the other AEAD algorithms defined in this specification, calling
 *   this function is not required.
 * - For vendor-defined algorithm, refer to the vendor documentation.
 *
 * \param[in,out] operation     Active AEAD operation.
 * \param ad_length             Size of the non-encrypted additional
 *                              authenticated data in bytes.
 * \param plaintext_length      Size of the plaintext to encrypt in bytes.
 *
 * \retval #PSA_SUCCESS
 *         Success.
 * \retval #PSA_ERROR_BAD_STATE
 *         The operation state is not valid (not set up, already completed,
 *         or psa_aead_update_ad() or psa_aead_update() already called).
 * \retval #PSA_ERROR_INVALID_ARGUMENT
 *         At least one of the lengths is not acceptable for the chosen
 *         algorithm.
 * \retval #PSA_ERROR_INSUFFICIENT_MEMORY
 * \retval #PSA_ERROR_COMMUNICATION_FAILURE
 * \retval #PSA_ERROR_HARDWARE_FAILURE
 * \retval #PSA_ERROR_TAMPERING_DETECTED
 */
psa_status_t psa_aead_set_lengths(psa_aead_operation_t *operation,
                                  size_t ad_length,
                                  size_t plaintext_length);

/** Pass additional data to an active AEAD operation.
 *
 * Additional data is authenticated, but not encrypted.
 *
 * You may call this function multiple times to pass successive fragments
 * of the additional data. You may not call this function after passing
 * data to encrypt or decrypt with psa_aead_update().
 *
 * Before calling this function, you must:
 * 1. Call either psa_aead_encrypt_setup() or psa_aead_decrypt_setup().
 * 2. Set the nonce with psa_aead_generate_nonce() or psa_aead_set_nonce().
 *
 * If this function returns an error status, the operation becomes inactive.
 *
 * \warning When decrypting, until psa_aead_verify() has returned #PSA_SUCCESS,
 *          there is no guarantee that the input is valid. Therefore, until
 *          you have called psa_aead_verify() and it has returned #PSA_SUCCESS,
 *          treat the input as untrusted and prepare to undo any action that
 *          depends on the input if psa_aead_verify() returns an error status.
 *
 * \param[in,out] operation     Active AEAD operation.
 * \param[in] input             Buffer containing the fragment of
 *                              additional data.
 * \param input_length          Size of the \p input buffer in bytes.
 *
 * \retval #PSA_SUCCESS
 *         Success.
 * \retval #PSA_ERROR_BAD_STATE
 *         The operation state is not valid (not set up, nonce not set,
 *         psa_aead_update() already called, or operation already completed).
 * \retval #PSA_ERROR_INVALID_ARGUMENT
 *         The total input length overflows the additional data length that
 *         was previously specified with psa_aead_set_lengths().
 * \retval #PSA_ERROR_INSUFFICIENT_MEMORY
 * \retval #PSA_ERROR_COMMUNICATION_FAILURE
 * \retval #PSA_ERROR_HARDWARE_FAILURE
 * \retval #PSA_ERROR_TAMPERING_DETECTED
 */
psa_status_t psa_aead_update_ad(psa_aead_operation_t *operation,
                                const uint8_t *input,
                                size_t input_length);

/** Encrypt or decrypt a message fragment in an active AEAD operation.
 *
 * Before calling this function, you must:
 * 1. Call either psa_aead_encrypt_setup() or psa_aead_decrypt_setup().
 *    The choice of setup function determines whether this function
 *    encrypts or decrypts its input.
 * 2. Set the nonce with psa_aead_generate_nonce() or psa_aead_set_nonce().
 * 3. Call psa_aead_update_ad() to pass all the additional data.
 *
 * If this function returns an error status, the operation becomes inactive.
 *
 * \warning When decrypting, until psa_aead_verify() has returned #PSA_SUCCESS,
 *          there is no guarantee that the input is valid. Therefore, until
 *          you have called psa_aead_verify() and it has returned #PSA_SUCCESS:
 *          - Do not use the output in any way other than storing it in a
 *            confidential location. If you take any action that depends
 *            on the tentative decrypted data, this action will need to be
 *            undone if the input turns out not to be valid. Furthermore,
 *            if an adversary can observe that this action took place
 *            (for example through timing), they may be able to use this
 *            fact as an oracle to decrypt any message encrypted with the
 *            same key.
 *          - In particular, do not copy the output anywhere but to a
 *            memory or storage space that you have exclusive access to.
 *
 * \param[in,out] operation     Active AEAD operation.
 * \param[in] input             Buffer containing the message fragment to
 *                              encrypt or decrypt.
 * \param input_length          Size of the \p input buffer in bytes.
 * \param[out] output           Buffer where the output is to be written.
 * \param output_size           Size of the \p output buffer in bytes.
 * \param[out] output_length    On success, the number of bytes
 *                              that make up the returned output.
 *
 * \retval #PSA_SUCCESS
 *         Success.
 * \retval #PSA_ERROR_BAD_STATE
 *         The operation state is not valid (not set up, nonce not set
 *         or already completed).
 * \retval #PSA_ERROR_BUFFER_TOO_SMALL
 *         The size of the \p output buffer is too small.
 * \retval #PSA_ERROR_INVALID_ARGUMENT
 *         The total length of input to psa_aead_update_ad() so far is
 *         less than the additional data length that was previously
 *         specified with psa_aead_set_lengths().
 * \retval #PSA_ERROR_INVALID_ARGUMENT
 *         The total input length overflows the plaintext length that
 *         was previously specified with psa_aead_set_lengths().
 * \retval #PSA_ERROR_INSUFFICIENT_MEMORY
 * \retval #PSA_ERROR_COMMUNICATION_FAILURE
 * \retval #PSA_ERROR_HARDWARE_FAILURE
 * \retval #PSA_ERROR_TAMPERING_DETECTED
 */
psa_status_t psa_aead_update(psa_aead_operation_t *operation,
                             const uint8_t *input,
                             size_t input_length,
                             unsigned char *output,
                             size_t output_size,
                             size_t *output_length);

/** Finish encrypting a message in an AEAD operation.
 *
 * The operation must have been set up with psa_aead_encrypt_setup().
 *
 * This function finishes the authentication of the additional data
 * formed by concatenating the inputs passed to preceding calls to
 * psa_aead_update_ad() with the plaintext formed by concatenating the
 * inputs passed to preceding calls to psa_aead_update().
 *
 * This function has two output buffers:
 * - \p ciphertext contains trailing ciphertext that was buffered from
 *   preceding calls to psa_aead_update(). For all standard AEAD algorithms,
 *   psa_aead_update() does not buffer any output and therefore \p ciphertext
 *   will not contain any output and can be a 0-sized buffer.
 * - \p tag contains the authentication tag. Its length is always
 *   #PSA_AEAD_TAG_LENGTH(\c alg) where \c alg is the AEAD algorithm
 *   that the operation performs.
 *
 * When this function returns, the operation becomes inactive.
 *
 * \param[in,out] operation     Active AEAD operation.
 * \param[out] ciphertext       Buffer where the last part of the ciphertext
 *                              is to be written.
 * \param ciphertext_size       Size of the \p ciphertext buffer in bytes.
 * \param[out] ciphertext_length On success, the number of bytes of
 *                              returned ciphertext.
 * \param[out] tag              Buffer where the authentication tag is
 *                              to be written.
 * \param tag_size              Size of the \p tag buffer in bytes.
 * \param[out] tag_length       On success, the number of bytes
 *                              that make up the returned tag.
 *
 * \retval #PSA_SUCCESS
 *         Success.
 * \retval #PSA_ERROR_BAD_STATE
 *         The operation state is not valid (not set up, nonce not set,
 *         decryption, or already completed).
 * \retval #PSA_ERROR_BUFFER_TOO_SMALL
 *         The size of the \p ciphertext or \p tag buffer is too small.
 * \retval #PSA_ERROR_INVALID_ARGUMENT
 *         The total length of input to psa_aead_update_ad() so far is
 *         less than the additional data length that was previously
 *         specified with psa_aead_set_lengths().
 * \retval #PSA_ERROR_INVALID_ARGUMENT
 *         The total length of input to psa_aead_update() so far is
 *         less than the plaintext length that was previously
 *         specified with psa_aead_set_lengths().
 * \retval #PSA_ERROR_INSUFFICIENT_MEMORY
 * \retval #PSA_ERROR_COMMUNICATION_FAILURE
 * \retval #PSA_ERROR_HARDWARE_FAILURE
 * \retval #PSA_ERROR_TAMPERING_DETECTED
 */
psa_status_t psa_aead_finish(psa_aead_operation_t *operation,
                             uint8_t *ciphertext,
                             size_t ciphertext_size,
                             size_t *ciphertext_length,
                             uint8_t *tag,
                             size_t tag_size,
                             size_t *tag_length);

/** Finish authenticating and decrypting a message in an AEAD operation.
 *
 * The operation must have been set up with psa_aead_decrypt_setup().
 *
 * This function finishes the authentication of the additional data
 * formed by concatenating the inputs passed to preceding calls to
 * psa_aead_update_ad() with the ciphertext formed by concatenating the
 * inputs passed to preceding calls to psa_aead_update().
 *
 * When this function returns, the operation becomes inactive.
 *
 * \param[in,out] operation     Active AEAD operation.
 * \param[in] tag               Buffer containing the authentication tag.
 * \param tag_length            Size of the \p tag buffer in bytes.
 *
 * \retval #PSA_SUCCESS
 *         Success.
 * \retval #PSA_ERROR_BAD_STATE
 *         The operation state is not valid (not set up, nonce not set,
 *         encryption, or already completed).
 * \retval #PSA_ERROR_INVALID_ARGUMENT
 *         The total length of input to psa_aead_update_ad() so far is
 *         less than the additional data length that was previously
 *         specified with psa_aead_set_lengths().
 * \retval #PSA_ERROR_INVALID_ARGUMENT
 *         The total length of input to psa_aead_update() so far is
 *         less than the plaintext length that was previously
 *         specified with psa_aead_set_lengths().
 * \retval #PSA_ERROR_INSUFFICIENT_MEMORY
 * \retval #PSA_ERROR_COMMUNICATION_FAILURE
 * \retval #PSA_ERROR_HARDWARE_FAILURE
 * \retval #PSA_ERROR_TAMPERING_DETECTED
 */
psa_status_t psa_aead_verify(psa_aead_operation_t *operation,
                             const uint8_t *tag,
                             size_t tag_length);

/** Abort an AEAD operation.
 *
 * Aborting an operation frees all associated resources except for the
 * \p operation structure itself. Once aborted, the operation object
 * can be reused for another operation by calling
 * psa_aead_encrypt_setup() or psa_aead_decrypt_setup() again.
 *
 * You may call this function any time after the operation object has
 * been initialized by any of the following methods:
 * - A call to psa_aead_encrypt_setup() or psa_aead_decrypt_setup(),
 *   whether it succeeds or not.
 * - Initializing the \c struct to all-bits-zero.
 * - Initializing the \c struct to logical zeros, e.g.
 *   `psa_aead_operation_t operation = {0}`.
 *
 * In particular, calling psa_aead_abort() after the operation has been
 * terminated by a call to psa_aead_abort() or psa_aead_finish()
 * is safe and has no effect.
 *
 * \param[in,out] operation     Initialized AEAD operation.
 *
 * \retval #PSA_SUCCESS
 * \retval #PSA_ERROR_BAD_STATE
 *         \p operation is not an active AEAD operation.
 * \retval #PSA_ERROR_COMMUNICATION_FAILURE
 * \retval #PSA_ERROR_HARDWARE_FAILURE
 * \retval #PSA_ERROR_TAMPERING_DETECTED
 */
psa_status_t psa_aead_abort(psa_aead_operation_t *operation);

/**@}*/

/** \defgroup asymmetric Asymmetric cryptography
 * @{
 */

/**
 * \brief Sign a hash or short message with a private key.
 *
 * Note that to perform a hash-and-sign signature algorithm, you must
 * first calculate the hash by calling psa_hash_setup(), psa_hash_update()
 * and psa_hash_finish(). Then pass the resulting hash as the \p hash
 * parameter to this function. You can use #PSA_ALG_SIGN_GET_HASH(\p alg)
 * to determine the hash algorithm to use.
 *
 * \param handle                Handle to the key to use for the operation.
 *                              It must be an asymmetric key pair.
 * \param alg                   A signature algorithm that is compatible with
 *                              the type of \p handle.
 * \param[in] hash              The hash or message to sign.
 * \param hash_length           Size of the \p hash buffer in bytes.
 * \param[out] signature        Buffer where the signature is to be written.
 * \param signature_size        Size of the \p signature buffer in bytes.
 * \param[out] signature_length On success, the number of bytes
 *                              that make up the returned signature value.
 *
 * \retval #PSA_SUCCESS
 * \retval #PSA_ERROR_BUFFER_TOO_SMALL
 *         The size of the \p signature buffer is too small. You can
 *         determine a sufficient buffer size by calling
 *         #PSA_ASYMMETRIC_SIGN_OUTPUT_SIZE(\c key_type, \c key_bits, \p alg)
 *         where \c key_type and \c key_bits are the type and bit-size
 *         respectively of \p handle.
 * \retval #PSA_ERROR_NOT_SUPPORTED
 * \retval #PSA_ERROR_INVALID_ARGUMENT
 * \retval #PSA_ERROR_INSUFFICIENT_MEMORY
 * \retval #PSA_ERROR_COMMUNICATION_FAILURE
 * \retval #PSA_ERROR_HARDWARE_FAILURE
 * \retval #PSA_ERROR_TAMPERING_DETECTED
 * \retval #PSA_ERROR_INSUFFICIENT_ENTROPY
 * \retval #PSA_ERROR_BAD_STATE
 *         The library has not been previously initialized by psa_crypto_init().
 *         It is implementation-dependent whether a failure to initialize
 *         results in this error code.
 */
psa_status_t psa_asymmetric_sign(psa_key_handle_t handle,
                                 psa_algorithm_t alg,
                                 const uint8_t *hash,
                                 size_t hash_length,
                                 uint8_t *signature,
                                 size_t signature_size,
                                 size_t *signature_length);

/**
 * \brief Verify the signature a hash or short message using a public key.
 *
 * Note that to perform a hash-and-sign signature algorithm, you must
 * first calculate the hash by calling psa_hash_setup(), psa_hash_update()
 * and psa_hash_finish(). Then pass the resulting hash as the \p hash
 * parameter to this function. You can use #PSA_ALG_SIGN_GET_HASH(\p alg)
 * to determine the hash algorithm to use.
 *
 * \param handle            Handle to the key to use for the operation.
 *                          It must be a public key or an asymmetric key pair.
 * \param alg               A signature algorithm that is compatible with
 *                          the type of \p handle.
 * \param[in] hash          The hash or message whose signature is to be
 *                          verified.
 * \param hash_length       Size of the \p hash buffer in bytes.
 * \param[in] signature     Buffer containing the signature to verify.
 * \param signature_length  Size of the \p signature buffer in bytes.
 *
 * \retval #PSA_SUCCESS
 *         The signature is valid.
 * \retval #PSA_ERROR_INVALID_SIGNATURE
 *         The calculation was perfomed successfully, but the passed
 *         signature is not a valid signature.
 * \retval #PSA_ERROR_NOT_SUPPORTED
 * \retval #PSA_ERROR_INVALID_ARGUMENT
 * \retval #PSA_ERROR_INSUFFICIENT_MEMORY
 * \retval #PSA_ERROR_COMMUNICATION_FAILURE
 * \retval #PSA_ERROR_HARDWARE_FAILURE
 * \retval #PSA_ERROR_TAMPERING_DETECTED
 * \retval #PSA_ERROR_BAD_STATE
 *         The library has not been previously initialized by psa_crypto_init().
 *         It is implementation-dependent whether a failure to initialize
 *         results in this error code.
 */
psa_status_t psa_asymmetric_verify(psa_key_handle_t handle,
                                   psa_algorithm_t alg,
                                   const uint8_t *hash,
                                   size_t hash_length,
                                   const uint8_t *signature,
                                   size_t signature_length);

/**
 * \brief Encrypt a short message with a public key.
 *
 * \param handle                Handle to the key to use for the operation.
 *                              It must be a public key or an asymmetric
 *                              key pair.
 * \param alg                   An asymmetric encryption algorithm that is
 *                              compatible with the type of \p handle.
 * \param[in] input             The message to encrypt.
 * \param input_length          Size of the \p input buffer in bytes.
 * \param[in] salt              A salt or label, if supported by the
 *                              encryption algorithm.
 *                              If the algorithm does not support a
 *                              salt, pass \c NULL.
 *                              If the algorithm supports an optional
 *                              salt and you do not want to pass a salt,
 *                              pass \c NULL.
 *
 *                              - For #PSA_ALG_RSA_PKCS1V15_CRYPT, no salt is
 *                                supported.
 * \param salt_length           Size of the \p salt buffer in bytes.
 *                              If \p salt is \c NULL, pass 0.
 * \param[out] output           Buffer where the encrypted message is to
 *                              be written.
 * \param output_size           Size of the \p output buffer in bytes.
 * \param[out] output_length    On success, the number of bytes
 *                              that make up the returned output.
 *
 * \retval #PSA_SUCCESS
 * \retval #PSA_ERROR_BUFFER_TOO_SMALL
 *         The size of the \p output buffer is too small. You can
 *         determine a sufficient buffer size by calling
 *         #PSA_ASYMMETRIC_ENCRYPT_OUTPUT_SIZE(\c key_type, \c key_bits, \p alg)
 *         where \c key_type and \c key_bits are the type and bit-size
 *         respectively of \p handle.
 * \retval #PSA_ERROR_NOT_SUPPORTED
 * \retval #PSA_ERROR_INVALID_ARGUMENT
 * \retval #PSA_ERROR_INSUFFICIENT_MEMORY
 * \retval #PSA_ERROR_COMMUNICATION_FAILURE
 * \retval #PSA_ERROR_HARDWARE_FAILURE
 * \retval #PSA_ERROR_TAMPERING_DETECTED
 * \retval #PSA_ERROR_INSUFFICIENT_ENTROPY
 * \retval #PSA_ERROR_BAD_STATE
 *         The library has not been previously initialized by psa_crypto_init().
 *         It is implementation-dependent whether a failure to initialize
 *         results in this error code.
 */
psa_status_t psa_asymmetric_encrypt(psa_key_handle_t handle,
                                    psa_algorithm_t alg,
                                    const uint8_t *input,
                                    size_t input_length,
                                    const uint8_t *salt,
                                    size_t salt_length,
                                    uint8_t *output,
                                    size_t output_size,
                                    size_t *output_length);

/**
 * \brief Decrypt a short message with a private key.
 *
 * \param handle                Handle to the key to use for the operation.
 *                              It must be an asymmetric key pair.
 * \param alg                   An asymmetric encryption algorithm that is
 *                              compatible with the type of \p handle.
 * \param[in] input             The message to decrypt.
 * \param input_length          Size of the \p input buffer in bytes.
 * \param[in] salt              A salt or label, if supported by the
 *                              encryption algorithm.
 *                              If the algorithm does not support a
 *                              salt, pass \c NULL.
 *                              If the algorithm supports an optional
 *                              salt and you do not want to pass a salt,
 *                              pass \c NULL.
 *
 *                              - For #PSA_ALG_RSA_PKCS1V15_CRYPT, no salt is
 *                                supported.
 * \param salt_length           Size of the \p salt buffer in bytes.
 *                              If \p salt is \c NULL, pass 0.
 * \param[out] output           Buffer where the decrypted message is to
 *                              be written.
 * \param output_size           Size of the \c output buffer in bytes.
 * \param[out] output_length    On success, the number of bytes
 *                              that make up the returned output.
 *
 * \retval #PSA_SUCCESS
 * \retval #PSA_ERROR_BUFFER_TOO_SMALL
 *         The size of the \p output buffer is too small. You can
 *         determine a sufficient buffer size by calling
 *         #PSA_ASYMMETRIC_DECRYPT_OUTPUT_SIZE(\c key_type, \c key_bits, \p alg)
 *         where \c key_type and \c key_bits are the type and bit-size
 *         respectively of \p handle.
 * \retval #PSA_ERROR_NOT_SUPPORTED
 * \retval #PSA_ERROR_INVALID_ARGUMENT
 * \retval #PSA_ERROR_INSUFFICIENT_MEMORY
 * \retval #PSA_ERROR_COMMUNICATION_FAILURE
 * \retval #PSA_ERROR_HARDWARE_FAILURE
 * \retval #PSA_ERROR_TAMPERING_DETECTED
 * \retval #PSA_ERROR_INSUFFICIENT_ENTROPY
 * \retval #PSA_ERROR_INVALID_PADDING
 * \retval #PSA_ERROR_BAD_STATE
 *         The library has not been previously initialized by psa_crypto_init().
 *         It is implementation-dependent whether a failure to initialize
 *         results in this error code.
 */
psa_status_t psa_asymmetric_decrypt(psa_key_handle_t handle,
                                    psa_algorithm_t alg,
                                    const uint8_t *input,
                                    size_t input_length,
                                    const uint8_t *salt,
                                    size_t salt_length,
                                    uint8_t *output,
                                    size_t output_size,
                                    size_t *output_length);

/**@}*/

/** \defgroup generators Generators
 * @{
 */

/** The type of the state data structure for generators.
 *
 * Before calling any function on a generator, the application must
 * initialize it by any of the following means:
 * - Set the structure to all-bits-zero, for example:
 *   \code
 *   psa_crypto_generator_t generator;
 *   memset(&generator, 0, sizeof(generator));
 *   \endcode
 * - Initialize the structure to logical zero values, for example:
 *   \code
 *   psa_crypto_generator_t generator = {0};
 *   \endcode
 * - Initialize the structure to the initializer #PSA_CRYPTO_GENERATOR_INIT,
 *   for example:
 *   \code
 *   psa_crypto_generator_t generator = PSA_CRYPTO_GENERATOR_INIT;
 *   \endcode
 * - Assign the result of the function psa_crypto_generator_init()
 *   to the structure, for example:
 *   \code
 *   psa_crypto_generator_t generator;
 *   generator = psa_crypto_generator_init();
 *   \endcode
 *
 * This is an implementation-defined \c struct. Applications should not
 * make any assumptions about the content of this structure except
 * as directed by the documentation of a specific implementation.
 */
typedef struct psa_crypto_generator_s psa_crypto_generator_t;

/** \def PSA_CRYPTO_GENERATOR_INIT
 *
 * This macro returns a suitable initializer for a generator object
 * of type #psa_crypto_generator_t.
 */
#ifdef __DOXYGEN_ONLY__
/* This is an example definition for documentation purposes.
 * Implementations should define a suitable value in `crypto_struct.h`.
 */
#define PSA_CRYPTO_GENERATOR_INIT {0}
#endif

/** Return an initial value for a generator object.
 */
static psa_crypto_generator_t psa_crypto_generator_init(void);

/** Retrieve the current capacity of a generator.
 *
 * The capacity of a generator is the maximum number of bytes that it can
 * return. Reading *N* bytes from a generator reduces its capacity by *N*.
 *
 * \param[in] generator     The generator to query.
 * \param[out] capacity     On success, the capacity of the generator.
 *
 * \retval #PSA_SUCCESS
 * \retval #PSA_ERROR_BAD_STATE
 * \retval #PSA_ERROR_COMMUNICATION_FAILURE
 */
psa_status_t psa_get_generator_capacity(const psa_crypto_generator_t *generator,
                                        size_t *capacity);

/** Set the maximum capacity of a generator.
 *
 * \param[in,out] generator The generator object to modify.
 * \param capacity          The new capacity of the generator.
 *                          It must be less or equal to the generator's
 *                          current capacity.
 *
 * \retval #PSA_SUCCESS
 * \retval #PSA_ERROR_INVALID_ARGUMENT
 *         \p capacity is larger than the generator's current capacity.
 * \retval #PSA_ERROR_BAD_STATE
 * \retval #PSA_ERROR_COMMUNICATION_FAILURE
 */
psa_status_t psa_set_generator_capacity(psa_crypto_generator_t *generator,
                                        size_t capacity);

/** Read some data from a generator.
 *
 * This function reads and returns a sequence of bytes from a generator.
 * The data that is read is discarded from the generator. The generator's
 * capacity is decreased by the number of bytes read.
 *
 * \param[in,out] generator The generator object to read from.
 * \param[out] output       Buffer where the generator output will be
 *                          written.
 * \param output_length     Number of bytes to output.
 *
 * \retval #PSA_SUCCESS
 * \retval #PSA_ERROR_INSUFFICIENT_DATA
 *                          There were fewer than \p output_length bytes
 *                          in the generator. Note that in this case, no
 *                          output is written to the output buffer.
 *                          The generator's capacity is set to 0, thus
 *                          subsequent calls to this function will not
 *                          succeed, even with a smaller output buffer.
 * \retval #PSA_ERROR_BAD_STATE
 * \retval #PSA_ERROR_INSUFFICIENT_MEMORY
 * \retval #PSA_ERROR_COMMUNICATION_FAILURE
 * \retval #PSA_ERROR_HARDWARE_FAILURE
 * \retval #PSA_ERROR_TAMPERING_DETECTED
 */
psa_status_t psa_generator_read(psa_crypto_generator_t *generator,
                                uint8_t *output,
                                size_t output_length);

/** Generate a key deterministically from data read from a generator.
 *
 * This function uses the output of a generator to derive a key.
 * How much output it consumes and how the key is derived depends on the
 * key type.
 *
 * - For key types for which the key is an arbitrary sequence of bytes
 *   of a given size,
 *   this function is functionally equivalent to calling #psa_generator_read
 *   and passing the resulting output to #psa_import_key.
 *   However, this function has a security benefit:
 *   if the implementation provides an isolation boundary then
 *   the key material is not exposed outside the isolation boundary.
 *   As a consequence, for these key types, this function always consumes
 *   exactly (\p bits / 8) bytes from the generator.
 *   The following key types defined in this specification follow this scheme:
 *
 *     - #PSA_KEY_TYPE_AES;
 *     - #PSA_KEY_TYPE_ARC4;
 *     - #PSA_KEY_TYPE_CAMELLIA;
 *     - #PSA_KEY_TYPE_DERIVE;
 *     - #PSA_KEY_TYPE_HMAC.
 *
 * - For ECC keys on a Montgomery elliptic curve
 *   (#PSA_KEY_TYPE_ECC_KEYPAIR(\c curve) where \c curve designates a
 *   Montgomery curve), this function always draws a byte string whose
 *   length is determined by the curve, and sets the mandatory bits
 *   accordingly. That is:
 *
 *     - #PSA_ECC_CURVE_CURVE25519: draw a 32-byte string
 *       and process it as specified in RFC 7748 &sect;5.
 *     - #PSA_ECC_CURVE_CURVE448: draw a 56-byte string
 *       and process it as specified in RFC 7748 &sect;5.
 *
 * - For key types for which the key is represented by a single sequence of
 *   \p bits bits with constraints as to which bit sequences are acceptable,
 *   this function draws a byte string of length (\p bits / 8) bytes rounded
 *   up to the nearest whole number of bytes. If the resulting byte string
 *   is acceptable, it becomes the key, otherwise the drawn bytes are discarded.
 *   This process is repeated until an acceptable byte string is drawn.
 *   The byte string drawn from the generator is interpreted as specified
 *   for the output produced by psa_export_key().
 *   The following key types defined in this specification follow this scheme:
 *
 *     - #PSA_KEY_TYPE_DES.
 *       Force-set the parity bits, but discard forbidden weak keys.
 *       For 2-key and 3-key triple-DES, the three keys are generated
 *       successively (for example, for 3-key triple-DES,
 *       if the first 8 bytes specify a weak key and the next 8 bytes do not,
 *       discard the first 8 bytes, use the next 8 bytes as the first key,
 *       and continue reading output from the generator to derive the other
 *       two keys).
 *     - Finite-field Diffie-Hellman keys (#PSA_KEY_TYPE_DH_KEYPAIR),
 *       DSA keys (#PSA_KEY_TYPE_DSA_KEYPAIR), and
 *       ECC keys on a Weierstrass elliptic curve
 *       (#PSA_KEY_TYPE_ECC_KEYPAIR(\c curve) where \c curve designates a
 *       Weierstrass curve).
 *       For these key types, interpret the byte string as integer
 *       in big-endian order. Discard it if it is not in the range
 *       [0, *N* - 2] where *N* is the boundary of the private key domain
 *       (the prime *p* for Diffie-Hellman, the subprime *q* for DSA,
 *       or the order of the curve's base point for ECC).
 *       Add 1 to the resulting integer and use this as the private key *x*.
 *       This method allows compliance to NIST standards, specifically
 *       the methods titled "key-pair generation by testing candidates"
 *       in NIST SP 800-56A &sect;5.6.1.1.4 for Diffie-Hellman,
 *       in FIPS 186-4 &sect;B.1.2 for DSA, and
 *       in NIST SP 800-56A &sect;5.6.1.2.2 or
 *       FIPS 186-4 &sect;B.4.2 for elliptic curve keys.
 *
 * - For other key types, including #PSA_KEY_TYPE_RSA_KEYPAIR,
 *   the way in which the generator output is consumed is
 *   implementation-defined.
 *
 * In all cases, the data that is read is discarded from the generator.
 * The generator's capacity is decreased by the number of bytes read.
 *
 * \param[in] attributes    The attributes for the new key.
 * \param[out] handle       On success, a handle to the newly created key.
 *                          \c 0 on failure.
 * \param[in,out] generator The generator object to read from.
 *
 * \retval #PSA_SUCCESS
 *         Success.
 *         If the key is persistent, the key material and the key's metadata
 *         have been saved to persistent storage.
 * \retval #PSA_ERROR_ALREADY_EXISTS
 *         This is an attempt to create a persistent key, and there is
 *         already a persistent key with the given identifier.
 * \retval #PSA_ERROR_INSUFFICIENT_DATA
 *         There was not enough data to create the desired key.
 *         Note that in this case, no output is written to the output buffer.
 *         The generator's capacity is set to 0, thus subsequent calls to
 *         this function will not succeed, even with a smaller output buffer.
 * \retval #PSA_ERROR_NOT_SUPPORTED
 *         The key type or key size is not supported, either by the
 *         implementation in general or in this particular slot.
 * \retval #PSA_ERROR_BAD_STATE
 * \retval #PSA_ERROR_INSUFFICIENT_MEMORY
 * \retval #PSA_ERROR_INSUFFICIENT_STORAGE
 * \retval #PSA_ERROR_COMMUNICATION_FAILURE
 * \retval #PSA_ERROR_HARDWARE_FAILURE
 * \retval #PSA_ERROR_TAMPERING_DETECTED
 * \retval #PSA_ERROR_BAD_STATE
 *         The library has not been previously initialized by psa_crypto_init().
 *         It is implementation-dependent whether a failure to initialize
 *         results in this error code.
 */
psa_status_t psa_generator_import_key(const psa_key_attributes_t *attributes,
                                      psa_key_handle_t *handle,
                                      psa_crypto_generator_t *generator);

/** Abort a generator.
 *
 * Once a generator has been aborted, its capacity is zero.
 * Aborting a generator frees all associated resources except for the
 * \c generator structure itself.
 *
 * This function may be called at any time as long as the generator
 * object has been initialized to #PSA_CRYPTO_GENERATOR_INIT, to
 * psa_crypto_generator_init() or a zero value. In particular, it is valid
 * to call psa_generator_abort() twice, or to call psa_generator_abort()
 * on a generator that has not been set up.
 *
 * Once aborted, the generator object may be called.
 *
 * \param[in,out] generator    The generator to abort.
 *
 * \retval #PSA_SUCCESS
 * \retval #PSA_ERROR_BAD_STATE
 * \retval #PSA_ERROR_COMMUNICATION_FAILURE
 * \retval #PSA_ERROR_HARDWARE_FAILURE
 * \retval #PSA_ERROR_TAMPERING_DETECTED
 */
psa_status_t psa_generator_abort(psa_crypto_generator_t *generator);

/** Use the maximum possible capacity for a generator.
 *
 * Use this value as the capacity argument when setting up a generator
 * to indicate that the generator should have the maximum possible capacity.
 * The value of the maximum possible capacity depends on the generator
 * algorithm.
 */
#define PSA_GENERATOR_UNBRIDLED_CAPACITY ((size_t)(-1))

/**@}*/

/** \defgroup derivation Key derivation
 * @{
 */

/** Set up a key derivation operation.
 *
 * A key derivation algorithm takes some inputs and uses them to create
 * a byte generator which can be used to produce keys and other
 * cryptographic material.
 *
 * To use a generator for key derivation:
 * - Start with an initialized object of type #psa_crypto_generator_t.
 * - Call psa_key_derivation_setup() to select the algorithm.
 * - Provide the inputs for the key derivation by calling
 *   psa_key_derivation_input_bytes() or psa_key_derivation_input_key()
 *   as appropriate. Which inputs are needed, in what order, and whether
 *   they may be keys and if so of what type depends on the algorithm.
 * - Optionally set the generator's maximum capacity with
 *   psa_set_generator_capacity(). You may do this before, in the middle of
 *   or after providing inputs. For some algorithms, this step is mandatory
 *   because the output depends on the maximum capacity.
 * - Generate output with psa_generator_read() or
 *   psa_generator_import_key(). Successive calls to these functions
 *   use successive output bytes from the generator.
 * - Clean up the generator object with psa_generator_abort().
 *
 * \param[in,out] generator       The generator object to set up. It must
 *                                have been initialized but not set up yet.
 * \param alg                     The key derivation algorithm to compute
 *                                (\c PSA_ALG_XXX value such that
 *                                #PSA_ALG_IS_KEY_DERIVATION(\p alg) is true).
 *
 * \retval #PSA_SUCCESS
 *         Success.
 * \retval #PSA_ERROR_INVALID_ARGUMENT
 *         \c alg is not a key derivation algorithm.
 * \retval #PSA_ERROR_NOT_SUPPORTED
 *         \c alg is not supported or is not a key derivation algorithm.
 * \retval #PSA_ERROR_INSUFFICIENT_MEMORY
 * \retval #PSA_ERROR_COMMUNICATION_FAILURE
 * \retval #PSA_ERROR_HARDWARE_FAILURE
 * \retval #PSA_ERROR_TAMPERING_DETECTED
 * \retval #PSA_ERROR_BAD_STATE
 */
psa_status_t psa_key_derivation_setup(psa_crypto_generator_t *generator,
                                      psa_algorithm_t alg);

/** Provide an input for key derivation or key agreement.
 *
 * Which inputs are required and in what order depends on the algorithm.
 * Refer to the documentation of each key derivation or key agreement
 * algorithm for information.
 *
 * This function passes direct inputs. Some inputs must be passed as keys
 * using psa_key_derivation_input_key() instead of this function. Refer to
 * the documentation of individual step types for information.
 *
 * \param[in,out] generator       The generator object to use. It must
 *                                have been set up with
 *                                psa_key_derivation_setup() and must not
 *                                have produced any output yet.
 * \param step                    Which step the input data is for.
 * \param[in] data                Input data to use.
 * \param data_length             Size of the \p data buffer in bytes.
 *
 * \retval #PSA_SUCCESS
 *         Success.
 * \retval #PSA_ERROR_INVALID_ARGUMENT
 *         \c step is not compatible with the generator's algorithm.
 * \retval #PSA_ERROR_INVALID_ARGUMENT
 *         \c step does not allow direct inputs.
 * \retval #PSA_ERROR_INSUFFICIENT_MEMORY
 * \retval #PSA_ERROR_COMMUNICATION_FAILURE
 * \retval #PSA_ERROR_HARDWARE_FAILURE
 * \retval #PSA_ERROR_TAMPERING_DETECTED
 * \retval #PSA_ERROR_BAD_STATE
 *         The value of \p step is not valid given the state of \p generator.
 * \retval #PSA_ERROR_BAD_STATE
 *         The library has not been previously initialized by psa_crypto_init().
 *         It is implementation-dependent whether a failure to initialize
 *         results in this error code.
 */
psa_status_t psa_key_derivation_input_bytes(psa_crypto_generator_t *generator,
                                            psa_key_derivation_step_t step,
                                            const uint8_t *data,
                                            size_t data_length);

/** Provide an input for key derivation in the form of a key.
 *
 * Which inputs are required and in what order depends on the algorithm.
 * Refer to the documentation of each key derivation or key agreement
 * algorithm for information.
 *
 * This function passes key inputs. Some inputs must be passed as keys
 * of the appropriate type using this function, while others must be
 * passed as direct inputs using psa_key_derivation_input_bytes(). Refer to
 * the documentation of individual step types for information.
 *
 * \param[in,out] generator       The generator object to use. It must
 *                                have been set up with
 *                                psa_key_derivation_setup() and must not
 *                                have produced any output yet.
 * \param step                    Which step the input data is for.
 * \param handle                  Handle to the key. It must have an
 *                                appropriate type for \p step and must
 *                                allow the usage #PSA_KEY_USAGE_DERIVE.
 *
 * \retval #PSA_SUCCESS
 *         Success.
 * \retval #PSA_ERROR_INVALID_HANDLE
 * \retval #PSA_ERROR_DOES_NOT_EXIST
 * \retval #PSA_ERROR_NOT_PERMITTED
 * \retval #PSA_ERROR_INVALID_ARGUMENT
 *         \c step is not compatible with the generator's algorithm.
 * \retval #PSA_ERROR_INVALID_ARGUMENT
 *         \c step does not allow key inputs.
 * \retval #PSA_ERROR_INSUFFICIENT_MEMORY
 * \retval #PSA_ERROR_COMMUNICATION_FAILURE
 * \retval #PSA_ERROR_HARDWARE_FAILURE
 * \retval #PSA_ERROR_TAMPERING_DETECTED
 * \retval #PSA_ERROR_BAD_STATE
 *         The value of \p step is not valid given the state of \p generator.
 * \retval #PSA_ERROR_BAD_STATE
 *         The library has not been previously initialized by psa_crypto_init().
 *         It is implementation-dependent whether a failure to initialize
 *         results in this error code.
 */
psa_status_t psa_key_derivation_input_key(psa_crypto_generator_t *generator,
                                          psa_key_derivation_step_t step,
                                          psa_key_handle_t handle);

/** Perform a key agreement and use the shared secret as input to a key
 * derivation.
 *
 * A key agreement algorithm takes two inputs: a private key \p private_key
 * a public key \p peer_key.
 * The result of this function is passed as input to a key derivation.
 * The output of this key derivation can be extracted by reading from the
 * resulting generator to produce keys and other cryptographic material.
 *
 * \param[in,out] generator       The generator object to use. It must
 *                                have been set up with
 *                                psa_key_derivation_setup() with a
 *                                key agreement and derivation algorithm
 *                                \c alg (\c PSA_ALG_XXX value such that
 *                                #PSA_ALG_IS_KEY_AGREEMENT(\c alg) is true
 *                                and #PSA_ALG_IS_RAW_KEY_AGREEMENT(\c alg)
 *                                is false).
 *                                The generator must be ready for an
 *                                input of the type given by \p step.
 * \param step                    Which step the input data is for.
 * \param private_key             Handle to the private key to use.
 * \param[in] peer_key      Public key of the peer. The peer key must be in the
 *                          same format that psa_import_key() accepts for the
 *                          public key type corresponding to the type of
 *                          private_key. That is, this function performs the
 *                          equivalent of
 *                          #psa_import_key(`internal_public_key_handle`,
 *                          #PSA_KEY_TYPE_PUBLIC_KEY_OF_KEYPAIR(`private_key_type`),
 *                          `peer_key`, `peer_key_length`) where
 *                          `private_key_type` is the type of `private_key`.
 *                          For example, for EC keys, this means that peer_key
 *                          is interpreted as a point on the curve that the
 *                          private key is on. The standard formats for public
 *                          keys are documented in the documentation of
 *                          psa_export_public_key().
 * \param peer_key_length         Size of \p peer_key in bytes.
 *
 * \retval #PSA_SUCCESS
 *         Success.
 * \retval #PSA_ERROR_INVALID_HANDLE
 * \retval #PSA_ERROR_DOES_NOT_EXIST
 * \retval #PSA_ERROR_NOT_PERMITTED
 * \retval #PSA_ERROR_INVALID_ARGUMENT
 *         \c private_key is not compatible with \c alg,
 *         or \p peer_key is not valid for \c alg or not compatible with
 *         \c private_key.
 * \retval #PSA_ERROR_NOT_SUPPORTED
 *         \c alg is not supported or is not a key derivation algorithm.
 * \retval #PSA_ERROR_INSUFFICIENT_MEMORY
 * \retval #PSA_ERROR_COMMUNICATION_FAILURE
 * \retval #PSA_ERROR_HARDWARE_FAILURE
 * \retval #PSA_ERROR_TAMPERING_DETECTED
 */
psa_status_t psa_key_agreement(psa_crypto_generator_t *generator,
                               psa_key_derivation_step_t step,
                               psa_key_handle_t private_key,
                               const uint8_t *peer_key,
                               size_t peer_key_length);

/** Perform a key agreement and use the shared secret as input to a key
 * derivation.
 *
 * A key agreement algorithm takes two inputs: a private key \p private_key
 * a public key \p peer_key.
 *
 * \warning The raw result of a key agreement algorithm such as finite-field
 * Diffie-Hellman or elliptic curve Diffie-Hellman has biases and should
 * not be used directly as key material. It should instead be passed as
 * input to a key derivation algorithm. To chain a key agreement with
 * a key derivation, use psa_key_agreement() and other functions from
 * the key derivation and generator interface.
 *
 * \param alg                     The key agreement algorithm to compute
 *                                (\c PSA_ALG_XXX value such that
 *                                #PSA_ALG_IS_RAW_KEY_AGREEMENT(\p alg)
 *                                is true).
 * \param private_key             Handle to the private key to use.
 * \param[in] peer_key            Public key of the peer. It must be
 *                                in the same format that psa_import_key()
 *                                accepts. The standard formats for public
 *                                keys are documented in the documentation
 *                                of psa_export_public_key().
 * \param peer_key_length         Size of \p peer_key in bytes.
 * \param[out] output             Buffer where the decrypted message is to
 *                                be written.
 * \param output_size             Size of the \c output buffer in bytes.
 * \param[out] output_length      On success, the number of bytes
 *                                that make up the returned output.
 *
 * \retval #PSA_SUCCESS
 *         Success.
 * \retval #PSA_ERROR_INVALID_HANDLE
 * \retval #PSA_ERROR_EMPTY_SLOT
 * \retval #PSA_ERROR_NOT_PERMITTED
 * \retval #PSA_ERROR_INVALID_ARGUMENT
 *         \p alg is not a key agreement algorithm
 * \retval #PSA_ERROR_INVALID_ARGUMENT
 *         \p private_key is not compatible with \p alg,
 *         or \p peer_key is not valid for \p alg or not compatible with
 *         \p private_key.
 * \retval #PSA_ERROR_NOT_SUPPORTED
 *         \p alg is not a supported key agreement algorithm.
 * \retval #PSA_ERROR_INSUFFICIENT_MEMORY
 * \retval #PSA_ERROR_COMMUNICATION_FAILURE
 * \retval #PSA_ERROR_HARDWARE_FAILURE
 * \retval #PSA_ERROR_TAMPERING_DETECTED
 */
psa_status_t psa_key_agreement_raw_shared_secret(psa_algorithm_t alg,
                                                 psa_key_handle_t private_key,
                                                 const uint8_t *peer_key,
                                                 size_t peer_key_length,
                                                 uint8_t *output,
                                                 size_t output_size,
                                                 size_t *output_length);

/**@}*/

/** \defgroup random Random generation
 * @{
 */

/**
 * \brief Generate random bytes.
 *
 * \warning This function **can** fail! Callers MUST check the return status
 *          and MUST NOT use the content of the output buffer if the return
 *          status is not #PSA_SUCCESS.
 *
 * \note    To generate a key, use psa_generate_key() instead.
 *
 * \param[out] output       Output buffer for the generated data.
 * \param output_size       Number of bytes to generate and output.
 *
 * \retval #PSA_SUCCESS
 * \retval #PSA_ERROR_NOT_SUPPORTED
 * \retval #PSA_ERROR_INSUFFICIENT_ENTROPY
 * \retval #PSA_ERROR_COMMUNICATION_FAILURE
 * \retval #PSA_ERROR_HARDWARE_FAILURE
 * \retval #PSA_ERROR_TAMPERING_DETECTED
 * \retval #PSA_ERROR_BAD_STATE
 *         The library has not been previously initialized by psa_crypto_init().
 *         It is implementation-dependent whether a failure to initialize
 *         results in this error code.
 */
psa_status_t psa_generate_random(uint8_t *output,
                                 size_t output_size);

/**
 * \brief Generate a key or key pair.
 *
 * The key is generated randomly.
 * Its location, policy, type and size are taken from \p attributes.
 *
 * If the type requires additional domain parameters, these are taken
 * from \p attributes as well. The following types use domain parameters:
 * - When generating an RSA key (#PSA_KEY_TYPE_RSA_KEYPAIR),
 *   the default public exponent is 65537. This value is used if
 *   \p attributes was set with psa_set_key_type() or by passing an empty
 *   byte string as domain parameters to psa_set_key_domain_parameters().
 *   If psa_set_key_domain_parameters() was used to set a non-empty
 *   domain parameter string in \p attributes, this string is read as
 *   a big-endian integer which is used as the public exponent.
 * - When generating a DSA key (#PSA_KEY_TYPE_DSA_KEYPAIR) or a
 *   Diffie-Hellman key (#PSA_KEY_TYPE_DH_KEYPAIR), the domain parameters
 *   from \p attributes are interpreted as described for
 *   psa_set_key_domain_parameters().
 *
 * \param[in] attributes    The attributes for the new key.
 * \param[out] handle       On success, a handle to the newly created key.
 *                          \c 0 on failure.
 *
 * \retval #PSA_SUCCESS
 *         Success.
 *         If the key is persistent, the key material and the key's metadata
 *         have been saved to persistent storage.
 * \retval #PSA_ERROR_ALREADY_EXISTS
 *         This is an attempt to create a persistent key, and there is
 *         already a persistent key with the given identifier.
 * \retval #PSA_ERROR_NOT_SUPPORTED
 * \retval #PSA_ERROR_INVALID_ARGUMENT
 * \retval #PSA_ERROR_INSUFFICIENT_MEMORY
 * \retval #PSA_ERROR_INSUFFICIENT_ENTROPY
 * \retval #PSA_ERROR_COMMUNICATION_FAILURE
 * \retval #PSA_ERROR_HARDWARE_FAILURE
 * \retval #PSA_ERROR_TAMPERING_DETECTED
 * \retval #PSA_ERROR_BAD_STATE
 *         The library has not been previously initialized by psa_crypto_init().
 *         It is implementation-dependent whether a failure to initialize
 *         results in this error code.
 */
psa_status_t psa_generate_key(const psa_key_attributes_t *attributes,
                              psa_key_handle_t *handle);

/**@}*/

#ifdef __cplusplus
}
#endif

/* The file "crypto_sizes.h" contains definitions for size calculation
 * macros whose definitions are implementation-specific. */
#include "crypto_sizes.h"

/* The file "crypto_struct.h" contains definitions for
 * implementation-specific structs that are declared above. */
#include "crypto_struct.h"

/* The file "crypto_extra.h" contains vendor-specific definitions. This
 * can include vendor-defined algorithms, extra functions, etc. */
#include "crypto_extra.h"

#endif /* PSA_CRYPTO_H */