Add slot_number attribute
Add a slot_number field to psa_key_attributes_t and getter/setter
functions. Since slot numbers can have the value 0, indicate the
presence of the field via a separate flag.
In psa_get_key_attributes(), report the slot number if the key is in a
secure element.
When creating a key, for now, applications cannot choose a slot
number. A subsequent commit will add this capability in the secure
element HAL.
diff --git a/include/psa/crypto_extra.h b/include/psa/crypto_extra.h
index 6dfaa13..5359b58 100644
--- a/include/psa/crypto_extra.h
+++ b/include/psa/crypto_extra.h
@@ -104,6 +104,67 @@
return( attributes->core.policy.alg2 );
}
+#if defined(MBEDTLS_PSA_CRYPTO_SE_C)
+
+/** Retrieve the slot number where a key is stored.
+ *
+ * A slot number is only defined for keys that are stored in a secure
+ * element.
+ *
+ * This information is only useful if the secure element is not entirely
+ * managed through the PSA Cryptography API. It is up to the secure
+ * element driver to decide how PSA slot numbers map to any other interface
+ * that the secure element may have.
+ *
+ * \param[in] attributes The key attribute structure to query.
+ * \param[out] slot_number On success, the slot number containing the key.
+ *
+ * \retval #PSA_SUCCESS
+ * The key is located in a secure element, and \p *slot_number
+ * indicates the slot number that contains it.
+ * \retval #PSA_ERROR_NOT_PERMITTED
+ * The caller is not permitted to query the slot number.
+ * Mbed Crypto currently does not return this error.
+ * \retval #PSA_ERROR_INVALID_ARGUMENT
+ * The key is not located in a secure element.
+ */
+psa_status_t psa_get_key_slot_number(
+ const psa_key_attributes_t *attributes,
+ psa_key_slot_number_t *slot_number );
+
+/** Choose the slot number where a key is stored.
+ *
+ * This function declares a slot number in the specified attribute
+ * structure.
+ *
+ * A slot number is only meaningful for keys that are stored in a secure
+ * element. It is up to the secure element driver to decide how PSA slot
+ * numbers map to any other interface that the secure element may have.
+ *
+ * \note Setting a slot number in key attributes for a key creation can
+ * cause the following errors when creating the key:
+ * - #PSA_ERROR_NOT_SUPPORTED if the selected secure element does
+ * not support choosing a specific slot number.
+ * - #PSA_ERROR_NOT_PERMITTED if the caller is not permitted to
+ * choose slot numbers in general or to choose this specific slot.
+ * - #PSA_ERROR_INVALID_ARGUMENT if the chosen slot number is not
+ * valid in general or not valid for this specific key.
+ * - #PSA_ERROR_ALREADY_EXISTS if there is already a key in the
+ * selected slot.
+ *
+ * \param[out] attributes The attribute structure to write to.
+ * \param slot_number The slot number to set.
+ */
+static inline void psa_set_key_slot_number(
+ psa_key_attributes_t *attributes,
+ psa_key_slot_number_t slot_number )
+{
+ attributes->core.flags |= MBEDTLS_PSA_KA_FLAG_HAS_SLOT_NUMBER;
+ attributes->slot_number = slot_number;
+}
+
+#endif /* MBEDTLS_PSA_CRYPTO_SE_C */
+
/**@}*/
/**
diff --git a/include/psa/crypto_se_driver.h b/include/psa/crypto_se_driver.h
index f95eaeb..69cdaba 100644
--- a/include/psa/crypto_se_driver.h
+++ b/include/psa/crypto_se_driver.h
@@ -134,10 +134,17 @@
void *persistent_data,
psa_key_lifetime_t lifetime);
+#if defined(__DOXYGEN_ONLY__) || !defined(MBEDTLS_PSA_CRYPTO_SE_C)
+/* Mbed Crypto with secure element support enabled defines this type in
+ * crypto_types.h because it is also visible to applications through an
+ * implementation-specific extension.
+ * For the PSA Cryptography specification, this type is only visible
+ * via crypto_se_driver.h. */
/** An internal designation of a key slot between the core part of the
* PSA Crypto implementation and the driver. The meaning of this value
* is driver-dependent. */
typedef uint64_t psa_key_slot_number_t;
+#endif /* __DOXYGEN_ONLY__ || !MBEDTLS_PSA_CRYPTO_SE_C */
/**@}*/
diff --git a/include/psa/crypto_struct.h b/include/psa/crypto_struct.h
index 3bace60..fbfe77e 100644
--- a/include/psa/crypto_struct.h
+++ b/include/psa/crypto_struct.h
@@ -331,11 +331,13 @@
*/
typedef uint16_t psa_key_attributes_flag_t;
-#define MBEDLTS_PSA_KA_FLAG_SLOT_NUMBER ( (psa_key_attributes_flag_t) 0x0001 )
+#define MBEDTLS_PSA_KA_FLAG_HAS_SLOT_NUMBER \
+ ( (psa_key_attributes_flag_t) 0x0001 )
/* A mask of key attribute flags used externally only.
* Only meant for internal checks inside the library. */
#define MBEDTLS_PSA_KA_MASK_EXTERNAL_ONLY ( \
+ MBEDTLS_PSA_KA_FLAG_HAS_SLOT_NUMBER | \
0 )
/* A mask of key attribute flags used both internally and externally.
@@ -358,11 +360,19 @@
struct psa_key_attributes_s
{
psa_core_key_attributes_t core;
+#if defined(MBEDTLS_PSA_CRYPTO_SE_C)
+ psa_key_slot_number_t slot_number;
+#endif /* MBEDTLS_PSA_CRYPTO_SE_C */
void *domain_parameters;
size_t domain_parameters_size;
};
+#if defined(MBEDTLS_PSA_CRYPTO_SE_C)
+#define PSA_KEY_ATTRIBUTES_INIT {PSA_CORE_KEY_ATTRIBUTES_INIT, 0, NULL, 0}
+#else
#define PSA_KEY_ATTRIBUTES_INIT {PSA_CORE_KEY_ATTRIBUTES_INIT, NULL, 0}
+#endif
+
static inline struct psa_key_attributes_s psa_key_attributes_init( void )
{
const struct psa_key_attributes_s v = PSA_KEY_ATTRIBUTES_INIT;
diff --git a/include/psa/crypto_types.h b/include/psa/crypto_types.h
index 1944be4..9af4957 100644
--- a/include/psa/crypto_types.h
+++ b/include/psa/crypto_types.h
@@ -244,6 +244,17 @@
*/
typedef struct psa_key_attributes_s psa_key_attributes_t;
+
+#ifndef __DOXYGEN_ONLY__
+#if defined(MBEDTLS_PSA_CRYPTO_SE_C)
+/* Mbed Crypto defines this type in crypto_types.h because it is also
+ * visible to applications through an implementation-specific extension.
+ * For the PSA Cryptography specification, this type is only visible
+ * via crypto_se_driver.h. */
+typedef uint64_t psa_key_slot_number_t;
+#endif /* MBEDTLS_PSA_CRYPTO_SE_C */
+#endif /* !__DOXYGEN_ONLY__ */
+
/**@}*/
/** \defgroup derivation Key derivation