| /** |
| * \file ctr_drbg.h |
| * |
| * \brief This file contains CTR_DRBG definitions and functions. |
| * |
| * CTR_DRBG is a standardized way of building a PRNG from a block-cipher |
| * in counter mode operation, as defined in <em>NIST SP 800-90A: |
| * Recommendation for Random Number Generation Using Deterministic Random |
| * Bit Generators</em>. |
| * |
| * The Mbed TLS implementation of CTR_DRBG uses AES-256 (default) or AES-128 |
| * as the underlying block cipher. |
| * |
| * \warning Using 128-bit keys for CTR_DRBG limits the security of generated |
| * keys and operations that use random values generated to 128-bit security. |
| */ |
| /* |
| * Copyright (C) 2006-2018, Arm Limited (or its affiliates), 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. |
| * |
| * This file is part of Mbed TLS (https://tls.mbed.org) |
| */ |
| |
| #ifndef MBEDTLS_CTR_DRBG_H |
| #define MBEDTLS_CTR_DRBG_H |
| |
| #if !defined(MBEDTLS_CONFIG_FILE) |
| #include "mbedtls/config.h" |
| #else |
| #include MBEDTLS_CONFIG_FILE |
| #endif |
| |
| #include "mbedtls/aes.h" |
| |
| #if defined(MBEDTLS_THREADING_C) |
| #include "mbedtls/threading.h" |
| #endif |
| |
| #define MBEDTLS_ERR_CTR_DRBG_ENTROPY_SOURCE_FAILED -0x0034 /**< The entropy source failed. */ |
| #define MBEDTLS_ERR_CTR_DRBG_REQUEST_TOO_BIG -0x0036 /**< The requested random buffer length is too big. */ |
| #define MBEDTLS_ERR_CTR_DRBG_INPUT_TOO_BIG -0x0038 /**< The input (entropy + additional data) is too large. */ |
| #define MBEDTLS_ERR_CTR_DRBG_FILE_IO_ERROR -0x003A /**< Read or write error in file. */ |
| |
| #define MBEDTLS_CTR_DRBG_BLOCKSIZE 16 /**< The block size used by the cipher. */ |
| |
| #if defined(MBEDTLS_CTR_DRBG_USE_128_BIT_KEY) |
| #define MBEDTLS_CTR_DRBG_KEYSIZE 16 /**< The key size used by the cipher (compile-time choice: 128 bits). */ |
| #else |
| #define MBEDTLS_CTR_DRBG_KEYSIZE 32 /**< The key size used by the cipher (compile-time choice: 256 bits). */ |
| #endif |
| |
| #define MBEDTLS_CTR_DRBG_KEYBITS ( MBEDTLS_CTR_DRBG_KEYSIZE * 8 ) /**< The key size for the DRBG operation, in bits. */ |
| #define MBEDTLS_CTR_DRBG_SEEDLEN ( MBEDTLS_CTR_DRBG_KEYSIZE + MBEDTLS_CTR_DRBG_BLOCKSIZE ) /**< The seed length, calculated as (counter + AES key). */ |
| |
| /** |
| * \name SECTION: Module settings |
| * |
| * The configuration options you can set for this module are in this section. |
| * Either change them in config.h or define them using the compiler command |
| * line. |
| * \{ |
| */ |
| |
| #if !defined(MBEDTLS_CTR_DRBG_ENTROPY_LEN) |
| #if defined(MBEDTLS_SHA512_C) && !defined(MBEDTLS_ENTROPY_FORCE_SHA256) |
| #define MBEDTLS_CTR_DRBG_ENTROPY_LEN 48 |
| /**< The amount of entropy used per seed by default: |
| * <ul><li>48 with SHA-512.</li> |
| * <li>32 with SHA-256.</li></ul> |
| */ |
| #else |
| #define MBEDTLS_CTR_DRBG_ENTROPY_LEN 32 |
| /**< Amount of entropy used per seed by default: |
| * <ul><li>48 with SHA-512.</li> |
| * <li>32 with SHA-256.</li></ul> |
| */ |
| #endif |
| #endif |
| |
| #if !defined(MBEDTLS_CTR_DRBG_RESEED_INTERVAL) |
| #define MBEDTLS_CTR_DRBG_RESEED_INTERVAL 10000 |
| /**< The interval before reseed is performed by default. */ |
| #endif |
| |
| #if !defined(MBEDTLS_CTR_DRBG_MAX_INPUT) |
| #define MBEDTLS_CTR_DRBG_MAX_INPUT 256 |
| /**< The maximum number of additional input Bytes. */ |
| #endif |
| |
| #if !defined(MBEDTLS_CTR_DRBG_MAX_REQUEST) |
| #define MBEDTLS_CTR_DRBG_MAX_REQUEST 1024 |
| /**< The maximum number of requested Bytes per call. */ |
| #endif |
| |
| #if !defined(MBEDTLS_CTR_DRBG_MAX_SEED_INPUT) |
| #define MBEDTLS_CTR_DRBG_MAX_SEED_INPUT 384 |
| /**< The maximum size of seed or reseed buffer. */ |
| #endif |
| |
| /* \} name SECTION: Module settings */ |
| |
| #define MBEDTLS_CTR_DRBG_PR_OFF 0 |
| /**< Prediction resistance is disabled. */ |
| #define MBEDTLS_CTR_DRBG_PR_ON 1 |
| /**< Prediction resistance is enabled. */ |
| |
| #ifdef __cplusplus |
| extern "C" { |
| #endif |
| |
| /** |
| * \brief The CTR_DRBG context structure. |
| */ |
| typedef struct mbedtls_ctr_drbg_context |
| { |
| unsigned char counter[16]; /*!< The counter (V). */ |
| int reseed_counter; /*!< The reseed counter. */ |
| int prediction_resistance; /*!< This determines whether prediction |
| resistance is enabled, that is |
| whether to systematically reseed before |
| each random generation. */ |
| size_t entropy_len; /*!< The amount of entropy grabbed on each |
| seed or reseed operation. */ |
| int reseed_interval; /*!< The reseed interval. */ |
| |
| mbedtls_aes_context aes_ctx; /*!< The AES context. */ |
| |
| /* |
| * Callbacks (Entropy) |
| */ |
| int (*f_entropy)(void *, unsigned char *, size_t); |
| /*!< The entropy callback function. */ |
| |
| void *p_entropy; /*!< The context for the entropy function. */ |
| |
| #if defined(MBEDTLS_THREADING_C) |
| mbedtls_threading_mutex_t mutex; |
| #endif |
| } |
| mbedtls_ctr_drbg_context; |
| |
| /** |
| * \brief This function initializes the CTR_DRBG context, |
| * and prepares it for mbedtls_ctr_drbg_seed() |
| * or mbedtls_ctr_drbg_free(). |
| * |
| * \param ctx The CTR_DRBG context to initialize. |
| */ |
| void mbedtls_ctr_drbg_init( mbedtls_ctr_drbg_context *ctx ); |
| |
| /** |
| * \brief This function seeds and sets up the CTR_DRBG |
| * entropy source for future reseeds. |
| * |
| * \note Personalization data can be provided in addition to the more generic |
| * entropy source, to make this instantiation as unique as possible. |
| * |
| * \param ctx The CTR_DRBG context to seed. |
| * \param f_entropy The entropy callback, taking as arguments the |
| * \p p_entropy context, the buffer to fill, and the |
| length of the buffer. |
| * \param p_entropy The entropy context. |
| * \param custom Personalization data, that is device-specific |
| identifiers. Can be NULL. |
| * \param len The length of the personalization data. |
| * |
| * \return \c 0 on success. |
| * \return #MBEDTLS_ERR_CTR_DRBG_ENTROPY_SOURCE_FAILED on failure. |
| */ |
| int mbedtls_ctr_drbg_seed( mbedtls_ctr_drbg_context *ctx, |
| int (*f_entropy)(void *, unsigned char *, size_t), |
| void *p_entropy, |
| const unsigned char *custom, |
| size_t len ); |
| |
| /** |
| * \brief This function clears CTR_CRBG context data. |
| * |
| * \param ctx The CTR_DRBG context to clear. |
| */ |
| void mbedtls_ctr_drbg_free( mbedtls_ctr_drbg_context *ctx ); |
| |
| /** |
| * \brief This function turns prediction resistance on or off. |
| * The default value is off. |
| * |
| * \note If enabled, entropy is gathered at the beginning of |
| * every call to mbedtls_ctr_drbg_random_with_add(). |
| * Only use this if your entropy source has sufficient |
| * throughput. |
| * |
| * \param ctx The CTR_DRBG context. |
| * \param resistance #MBEDTLS_CTR_DRBG_PR_ON or #MBEDTLS_CTR_DRBG_PR_OFF. |
| */ |
| void mbedtls_ctr_drbg_set_prediction_resistance( mbedtls_ctr_drbg_context *ctx, |
| int resistance ); |
| |
| /** |
| * \brief This function sets the amount of entropy grabbed on each |
| * seed or reseed. The default value is |
| * #MBEDTLS_CTR_DRBG_ENTROPY_LEN. |
| * |
| * \param ctx The CTR_DRBG context. |
| * \param len The amount of entropy to grab. |
| */ |
| void mbedtls_ctr_drbg_set_entropy_len( mbedtls_ctr_drbg_context *ctx, |
| size_t len ); |
| |
| /** |
| * \brief This function sets the reseed interval. |
| * The default value is #MBEDTLS_CTR_DRBG_RESEED_INTERVAL. |
| * |
| * \param ctx The CTR_DRBG context. |
| * \param interval The reseed interval. |
| */ |
| void mbedtls_ctr_drbg_set_reseed_interval( mbedtls_ctr_drbg_context *ctx, |
| int interval ); |
| |
| /** |
| * \brief This function reseeds the CTR_DRBG context, that is |
| * extracts data from the entropy source. |
| * |
| * \param ctx The CTR_DRBG context. |
| * \param additional Additional data to add to the state. Can be NULL. |
| * \param len The length of the additional data. |
| * |
| * \return \c 0 on success. |
| * \return #MBEDTLS_ERR_CTR_DRBG_ENTROPY_SOURCE_FAILED on failure. |
| */ |
| int mbedtls_ctr_drbg_reseed( mbedtls_ctr_drbg_context *ctx, |
| const unsigned char *additional, size_t len ); |
| |
| /** |
| * \brief This function updates the state of the CTR_DRBG context. |
| * |
| * \param ctx The CTR_DRBG context. |
| * \param additional The data to update the state with. |
| * \param add_len Length of \p additional in bytes. This must be at |
| * most #MBEDTLS_CTR_DRBG_MAX_SEED_INPUT. |
| * |
| * \return \c 0 on success. |
| * \return #MBEDTLS_ERR_CTR_DRBG_INPUT_TOO_BIG if |
| * \p add_len is more than |
| * #MBEDTLS_CTR_DRBG_MAX_SEED_INPUT. |
| * \return An error from the underlying AES cipher on failure. |
| */ |
| int mbedtls_ctr_drbg_update_ret( mbedtls_ctr_drbg_context *ctx, |
| const unsigned char *additional, |
| size_t add_len ); |
| |
| /** |
| * \brief This function updates a CTR_DRBG instance with additional |
| * data and uses it to generate random data. |
| * |
| * \note The function automatically reseeds if the reseed counter is exceeded. |
| * |
| * \param p_rng The CTR_DRBG context. This must be a pointer to a |
| * #mbedtls_ctr_drbg_context structure. |
| * \param output The buffer to fill. |
| * \param output_len The length of the buffer. |
| * \param additional Additional data to update. Can be NULL. |
| * \param add_len The length of the additional data. |
| * |
| * \return \c 0 on success. |
| * \return #MBEDTLS_ERR_CTR_DRBG_ENTROPY_SOURCE_FAILED or |
| * #MBEDTLS_ERR_CTR_DRBG_REQUEST_TOO_BIG on failure. |
| */ |
| int mbedtls_ctr_drbg_random_with_add( void *p_rng, |
| unsigned char *output, size_t output_len, |
| const unsigned char *additional, size_t add_len ); |
| |
| /** |
| * \brief This function uses CTR_DRBG to generate random data. |
| * |
| * \note The function automatically reseeds if the reseed counter is exceeded. |
| * |
| * \param p_rng The CTR_DRBG context. This must be a pointer to a |
| * #mbedtls_ctr_drbg_context structure. |
| * \param output The buffer to fill. |
| * \param output_len The length of the buffer. |
| * |
| * \return \c 0 on success. |
| * \return #MBEDTLS_ERR_CTR_DRBG_ENTROPY_SOURCE_FAILED or |
| * #MBEDTLS_ERR_CTR_DRBG_REQUEST_TOO_BIG on failure. |
| */ |
| int mbedtls_ctr_drbg_random( void *p_rng, |
| unsigned char *output, size_t output_len ); |
| |
| |
| #if ! defined(MBEDTLS_DEPRECATED_REMOVED) |
| #if defined(MBEDTLS_DEPRECATED_WARNING) |
| #define MBEDTLS_DEPRECATED __attribute__((deprecated)) |
| #else |
| #define MBEDTLS_DEPRECATED |
| #endif |
| /** |
| * \brief This function updates the state of the CTR_DRBG context. |
| * |
| * \deprecated Superseded by mbedtls_ctr_drbg_update_ret() |
| * in 2.16.0. |
| * |
| * \note If \p add_len is greater than |
| * #MBEDTLS_CTR_DRBG_MAX_SEED_INPUT, only the first |
| * #MBEDTLS_CTR_DRBG_MAX_SEED_INPUT Bytes are used. |
| * The remaining Bytes are silently discarded. |
| * |
| * \param ctx The CTR_DRBG context. |
| * \param additional The data to update the state with. |
| * \param add_len Length of \p additional data. |
| */ |
| MBEDTLS_DEPRECATED void mbedtls_ctr_drbg_update( |
| mbedtls_ctr_drbg_context *ctx, |
| const unsigned char *additional, |
| size_t add_len ); |
| #undef MBEDTLS_DEPRECATED |
| #endif /* !MBEDTLS_DEPRECATED_REMOVED */ |
| |
| #if defined(MBEDTLS_FS_IO) |
| /** |
| * \brief This function writes a seed file. |
| * |
| * \param ctx The CTR_DRBG context. |
| * \param path The name of the file. |
| * |
| * \return \c 0 on success. |
| * \return #MBEDTLS_ERR_CTR_DRBG_FILE_IO_ERROR on file error. |
| * \return #MBEDTLS_ERR_CTR_DRBG_ENTROPY_SOURCE_FAILED on |
| * failure. |
| */ |
| int mbedtls_ctr_drbg_write_seed_file( mbedtls_ctr_drbg_context *ctx, const char *path ); |
| |
| /** |
| * \brief This function reads and updates a seed file. The seed |
| * is added to this instance. |
| * |
| * \param ctx The CTR_DRBG context. |
| * \param path The name of the file. |
| * |
| * \return \c 0 on success. |
| * \return #MBEDTLS_ERR_CTR_DRBG_FILE_IO_ERROR on file error. |
| * \return #MBEDTLS_ERR_CTR_DRBG_ENTROPY_SOURCE_FAILED or |
| * #MBEDTLS_ERR_CTR_DRBG_INPUT_TOO_BIG on failure. |
| */ |
| int mbedtls_ctr_drbg_update_seed_file( mbedtls_ctr_drbg_context *ctx, const char *path ); |
| #endif /* MBEDTLS_FS_IO */ |
| |
| #if defined(MBEDTLS_SELF_TEST) |
| |
| /** |
| * \brief The CTR_DRBG checkup routine. |
| * |
| * \return \c 0 on success. |
| * \return \c 1 on failure. |
| */ |
| int mbedtls_ctr_drbg_self_test( int verbose ); |
| |
| #endif /* MBEDTLS_SELF_TEST */ |
| |
| /* Internal functions (do not call directly) */ |
| int mbedtls_ctr_drbg_seed_entropy_len( mbedtls_ctr_drbg_context *, |
| int (*)(void *, unsigned char *, size_t), void *, |
| const unsigned char *, size_t, size_t ); |
| |
| #ifdef __cplusplus |
| } |
| #endif |
| |
| #endif /* ctr_drbg.h */ |