/** * \file psa/crypto_extra.h * * \brief PSA cryptography module: Mbed TLS vendor extensions * * \note This file may not be included directly. Applications must * include psa/crypto.h. * * This file is reserved for vendor-specific definitions. */ /* * Copyright The Mbed TLS Contributors * 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_EXTRA_H #define PSA_CRYPTO_EXTRA_H #include "mbedtls/platform_util.h" #include "crypto_compat.h" #ifdef __cplusplus extern "C" { #endif /* UID for secure storage seed */ #define PSA_CRYPTO_ITS_RANDOM_SEED_UID 0xFFFFFF52 /** \addtogroup attributes * @{ */ /** \brief Declare the enrollment algorithm for a key. * * An operation on a key may indifferently use the algorithm set with * psa_set_key_algorithm() or with this function. * * \param[out] attributes The attribute structure to write to. * \param alg2 A second algorithm that the key may be used * for, in addition to the algorithm set with * psa_set_key_algorithm(). * * \warning Setting an enrollment algorithm is not recommended, because * using the same key with different algorithms can allow some * attacks based on arithmetic relations between different * computations made with the same key, or can escalate harmless * side channels into exploitable ones. Use this function only * if it is necessary to support a protocol for which it has been * verified that the usage of the key with multiple algorithms * is safe. */ static inline void psa_set_key_enrollment_algorithm( psa_key_attributes_t *attributes, psa_algorithm_t alg2) { attributes->core.policy.alg2 = alg2; } /** Retrieve the enrollment algorithm policy from key attributes. * * \param[in] attributes The key attribute structure to query. * * \return The enrollment algorithm stored in the attribute structure. */ static inline psa_algorithm_t psa_get_key_enrollment_algorithm( const psa_key_attributes_t *attributes) { 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; } /** Remove the slot number attribute from a key attribute structure. * * This function undoes the action of psa_set_key_slot_number(). * * \param[out] attributes The attribute structure to write to. */ static inline void psa_clear_key_slot_number( psa_key_attributes_t *attributes ) { attributes->core.flags &= ~MBEDTLS_PSA_KA_FLAG_HAS_SLOT_NUMBER; } /** Register a key that is already present in a secure element. * * The key must be located in a secure element designated by the * lifetime field in \p attributes, in the slot set with * psa_set_key_slot_number() in the attribute structure. * This function makes the key available through the key identifier * specified in \p attributes. * * \param[in] attributes The attributes of the existing key. * * \retval #PSA_SUCCESS * The key was successfully registered. * Note that depending on the design of the driver, this may or may * not guarantee that a key actually exists in the designated slot * and is compatible with the specified attributes. * \retval #PSA_ERROR_ALREADY_EXISTS * There is already a key with the identifier specified in * \p attributes. * \retval #PSA_ERROR_NOT_SUPPORTED * The secure element driver for the specified lifetime does not * support registering a key. * \retval #PSA_ERROR_INVALID_ARGUMENT * \p attributes specifies a lifetime which is not located * in a secure element. * \retval #PSA_ERROR_INVALID_ARGUMENT * No slot number is specified in \p attributes, * or the specified slot number is not valid. * \retval #PSA_ERROR_NOT_PERMITTED * The caller is not authorized to register the specified key slot. * \retval #PSA_ERROR_INSUFFICIENT_MEMORY * \retval #PSA_ERROR_INSUFFICIENT_STORAGE * \retval #PSA_ERROR_COMMUNICATION_FAILURE * \retval #PSA_ERROR_DATA_INVALID * \retval #PSA_ERROR_DATA_CORRUPT * \retval #PSA_ERROR_CORRUPTION_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 mbedtls_psa_register_se_key( const psa_key_attributes_t *attributes); #endif /* MBEDTLS_PSA_CRYPTO_SE_C */ /**@}*/ /** * \brief Library deinitialization. * * This function clears all data associated with the PSA layer, * including the whole key store. * * This is an Mbed TLS extension. */ void mbedtls_psa_crypto_free( void ); /** \brief Statistics about * resource consumption related to the PSA keystore. * * \note The content of this structure is not part of the stable API and ABI * of Mbed Crypto and may change arbitrarily from version to version. */ typedef struct mbedtls_psa_stats_s { /** Number of slots containing key material for a volatile key. */ size_t volatile_slots; /** Number of slots containing key material for a key which is in * internal persistent storage. */ size_t persistent_slots; /** Number of slots containing a reference to a key in a * secure element. */ size_t external_slots; /** Number of slots which are occupied, but do not contain * key material yet. */ size_t half_filled_slots; /** Number of slots that contain cache data. */ size_t cache_slots; /** Number of slots that are not used for anything. */ size_t empty_slots; /** Number of slots that are locked. */ size_t locked_slots; /** Largest key id value among open keys in internal persistent storage. */ psa_key_id_t max_open_internal_key_id; /** Largest key id value among open keys in secure elements. */ psa_key_id_t max_open_external_key_id; } mbedtls_psa_stats_t; /** \brief Get statistics about * resource consumption related to the PSA keystore. * * \note When Mbed Crypto is built as part of a service, with isolation * between the application and the keystore, the service may or * may not expose this function. */ void mbedtls_psa_get_stats( mbedtls_psa_stats_t *stats ); /** * \brief Inject an initial entropy seed for the random generator into * secure storage. * * This function injects data to be used as a seed for the random generator * used by the PSA Crypto implementation. On devices that lack a trusted * entropy source (preferably a hardware random number generator), * the Mbed PSA Crypto implementation uses this value to seed its * random generator. * * On devices without a trusted entropy source, this function must be * called exactly once in the lifetime of the device. On devices with * a trusted entropy source, calling this function is optional. * In all cases, this function may only be called before calling any * other function in the PSA Crypto API, including psa_crypto_init(). * * When this function returns successfully, it populates a file in * persistent storage. Once the file has been created, this function * can no longer succeed. * * If any error occurs, this function does not change the system state. * You can call this function again after correcting the reason for the * error if possible. * * \warning This function **can** fail! Callers MUST check the return status. * * \warning If you use this function, you should use it as part of a * factory provisioning process. The value of the injected seed * is critical to the security of the device. It must be * *secret*, *unpredictable* and (statistically) *unique per device*. * You should be generate it randomly using a cryptographically * secure random generator seeded from trusted entropy sources. * You should transmit it securely to the device and ensure * that its value is not leaked or stored anywhere beyond the * needs of transmitting it from the point of generation to * the call of this function, and erase all copies of the value * once this function returns. * * This is an Mbed TLS extension. * * \note This function is only available on the following platforms: * * If the compile-time option MBEDTLS_PSA_INJECT_ENTROPY is enabled. * Note that you must provide compatible implementations of * mbedtls_nv_seed_read and mbedtls_nv_seed_write. * * In a client-server integration of PSA Cryptography, on the client side, * if the server supports this feature. * \param[in] seed Buffer containing the seed value to inject. * \param[in] seed_size Size of the \p seed buffer. * The size of the seed in bytes must be greater * or equal to both #MBEDTLS_ENTROPY_MIN_PLATFORM * and #MBEDTLS_ENTROPY_BLOCK_SIZE. * It must be less or equal to * #MBEDTLS_ENTROPY_MAX_SEED_SIZE. * * \retval #PSA_SUCCESS * The seed value was injected successfully. The random generator * of the PSA Crypto implementation is now ready for use. * You may now call psa_crypto_init() and use the PSA Crypto * implementation. * \retval #PSA_ERROR_INVALID_ARGUMENT * \p seed_size is out of range. * \retval #PSA_ERROR_STORAGE_FAILURE * There was a failure reading or writing from storage. * \retval #PSA_ERROR_NOT_PERMITTED * The library has already been initialized. It is no longer * possible to call this function. */ psa_status_t mbedtls_psa_inject_entropy(const uint8_t *seed, size_t seed_size); /** \addtogroup crypto_types * @{ */ /** DSA public key. * * The import and export 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. */ #define PSA_KEY_TYPE_DSA_PUBLIC_KEY ((psa_key_type_t)0x4002) /** DSA key pair (private and public key). * * The import and export 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). * * Determinstic DSA key derivation with psa_generate_derived_key follows * FIPS 186-4 §B.1.2: 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*. * */ #define PSA_KEY_TYPE_DSA_KEY_PAIR ((psa_key_type_t)0x7002) /** Whether a key type is an DSA key (pair or public-only). */ #define PSA_KEY_TYPE_IS_DSA(type) \ (PSA_KEY_TYPE_PUBLIC_KEY_OF_KEY_PAIR(type) == PSA_KEY_TYPE_DSA_PUBLIC_KEY) #define PSA_ALG_DSA_BASE ((psa_algorithm_t)0x06000400) /** DSA signature with hashing. * * This is the signature scheme defined by FIPS 186-4, * with a random per-message secret number (*k*). * * \param hash_alg A hash algorithm (\c PSA_ALG_XXX value such that * #PSA_ALG_IS_HASH(\p hash_alg) is true). * This includes #PSA_ALG_ANY_HASH * when specifying the algorithm in a usage policy. * * \return The corresponding DSA signature algorithm. * \return Unspecified if \p hash_alg is not a supported * hash algorithm. */ #define PSA_ALG_DSA(hash_alg) \ (PSA_ALG_DSA_BASE | ((hash_alg) & PSA_ALG_HASH_MASK)) #define PSA_ALG_DETERMINISTIC_DSA_BASE ((psa_algorithm_t)0x06000500) #define PSA_ALG_DSA_DETERMINISTIC_FLAG PSA_ALG_ECDSA_DETERMINISTIC_FLAG /** Deterministic DSA signature with hashing. * * This is the deterministic variant defined by RFC 6979 of * the signature scheme defined by FIPS 186-4. * * \param hash_alg A hash algorithm (\c PSA_ALG_XXX value such that * #PSA_ALG_IS_HASH(\p hash_alg) is true). * This includes #PSA_ALG_ANY_HASH * when specifying the algorithm in a usage policy. * * \return The corresponding DSA signature algorithm. * \return Unspecified if \p hash_alg is not a supported * hash algorithm. */ #define PSA_ALG_DETERMINISTIC_DSA(hash_alg) \ (PSA_ALG_DETERMINISTIC_DSA_BASE | ((hash_alg) & PSA_ALG_HASH_MASK)) #define PSA_ALG_IS_DSA(alg) \ (((alg) & ~PSA_ALG_HASH_MASK & ~PSA_ALG_DSA_DETERMINISTIC_FLAG) == \ PSA_ALG_DSA_BASE) #define PSA_ALG_DSA_IS_DETERMINISTIC(alg) \ (((alg) & PSA_ALG_DSA_DETERMINISTIC_FLAG) != 0) #define PSA_ALG_IS_DETERMINISTIC_DSA(alg) \ (PSA_ALG_IS_DSA(alg) && PSA_ALG_DSA_IS_DETERMINISTIC(alg)) #define PSA_ALG_IS_RANDOMIZED_DSA(alg) \ (PSA_ALG_IS_DSA(alg) && !PSA_ALG_DSA_IS_DETERMINISTIC(alg)) /* We need to expand the sample definition of this macro from * the API definition. */ #undef PSA_ALG_IS_HASH_AND_SIGN #define PSA_ALG_IS_HASH_AND_SIGN(alg) \ (PSA_ALG_IS_RSA_PSS(alg) || PSA_ALG_IS_RSA_PKCS1V15_SIGN(alg) || \ PSA_ALG_IS_DSA(alg) || PSA_ALG_IS_ECDSA(alg)) /**@}*/ /** \addtogroup attributes * @{ */ /** Custom Diffie-Hellman group. * * For keys of type #PSA_KEY_TYPE_DH_PUBLIC_KEY(#PSA_DH_FAMILY_CUSTOM) or * #PSA_KEY_TYPE_DH_KEY_PAIR(#PSA_DH_FAMILY_CUSTOM), the group data comes * from domain parameters set by psa_set_key_domain_parameters(). */ #define PSA_DH_FAMILY_CUSTOM ((psa_dh_family_t) 0x7e) /** * \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. Use this function instead * of psa_set_key_type() when you need to specify domain parameters. * * The format for the required domain parameters varies based on the key type. * * - For RSA keys (#PSA_KEY_TYPE_RSA_PUBLIC_KEY or #PSA_KEY_TYPE_RSA_KEY_PAIR), * 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_KEY_PAIR), * the `Dss-Parms` format as defined by RFC 3279 §2.3.2. * ``` * Dss-Parms ::= SEQUENCE { * p INTEGER, * q INTEGER, * g INTEGER * } * ``` * - For Diffie-Hellman key exchange keys * (#PSA_KEY_TYPE_DH_PUBLIC_KEY(#PSA_DH_FAMILY_CUSTOM) or * #PSA_KEY_TYPE_DH_KEY_PAIR(#PSA_DH_FAMILY_CUSTOM)), the * `DomainParameters` format as defined by RFC 3279 §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. * * \note This is an experimental extension to the interface. It may change * in future versions of the library. * * \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(). * * \note This is an experimental extension to the interface. It may change * in future versions of the library. * * \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. * The buffer is guaranteed to be large * enough if its size in bytes is at least * the value given by * PSA_KEY_DOMAIN_PARAMETERS_SIZE(). * \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); /** Safe output buffer size for psa_get_key_domain_parameters(). * * This macro returns a compile-time constant if its arguments are * compile-time constants. * * \warning This function may call its arguments multiple times or * zero times, so you should not pass arguments that contain * side effects. * * \note This is an experimental extension to the interface. It may change * in future versions of the library. * * \param key_type A supported key type. * \param key_bits The size of the key in bits. * * \return If the parameters are valid and supported, return * a buffer size in bytes that guarantees that * psa_get_key_domain_parameters() will not fail with * #PSA_ERROR_BUFFER_TOO_SMALL. * If the parameters are a valid combination that is not supported * by the implementation, this macro shall return either a * sensible size or 0. * If the parameters are not valid, the * return value is unspecified. */ #define PSA_KEY_DOMAIN_PARAMETERS_SIZE(key_type, key_bits) \ (PSA_KEY_TYPE_IS_RSA(key_type) ? sizeof(int) : \ PSA_KEY_TYPE_IS_DH(key_type) ? PSA_DH_KEY_DOMAIN_PARAMETERS_SIZE(key_bits) : \ PSA_KEY_TYPE_IS_DSA(key_type) ? PSA_DSA_KEY_DOMAIN_PARAMETERS_SIZE(key_bits) : \ 0) #define PSA_DH_KEY_DOMAIN_PARAMETERS_SIZE(key_bits) \ (4 + (PSA_BITS_TO_BYTES(key_bits) + 5) * 3 /*without optional parts*/) #define PSA_DSA_KEY_DOMAIN_PARAMETERS_SIZE(key_bits) \ (4 + (PSA_BITS_TO_BYTES(key_bits) + 5) * 2 /*p, g*/ + 34 /*q*/) /**@}*/ /** \defgroup psa_tls_helpers TLS helper functions * @{ */ #if defined(MBEDTLS_ECP_C) #include /** Convert an ECC curve identifier from the Mbed TLS encoding to PSA. * * \note This function is provided solely for the convenience of * Mbed TLS and may be removed at any time without notice. * * \param grpid An Mbed TLS elliptic curve identifier * (`MBEDTLS_ECP_DP_xxx`). * \param[out] bits On success, the bit size of the curve. * * \return The corresponding PSA elliptic curve identifier * (`PSA_ECC_FAMILY_xxx`). * \return \c 0 on failure (\p grpid is not recognized). */ static inline psa_ecc_family_t mbedtls_ecc_group_to_psa( mbedtls_ecp_group_id grpid, size_t *bits ) { switch( grpid ) { case MBEDTLS_ECP_DP_SECP192R1: *bits = 192; return( PSA_ECC_FAMILY_SECP_R1 ); case MBEDTLS_ECP_DP_SECP224R1: *bits = 224; return( PSA_ECC_FAMILY_SECP_R1 ); case MBEDTLS_ECP_DP_SECP256R1: *bits = 256; return( PSA_ECC_FAMILY_SECP_R1 ); case MBEDTLS_ECP_DP_SECP384R1: *bits = 384; return( PSA_ECC_FAMILY_SECP_R1 ); case MBEDTLS_ECP_DP_SECP521R1: *bits = 521; return( PSA_ECC_FAMILY_SECP_R1 ); case MBEDTLS_ECP_DP_BP256R1: *bits = 256; return( PSA_ECC_FAMILY_BRAINPOOL_P_R1 ); case MBEDTLS_ECP_DP_BP384R1: *bits = 384; return( PSA_ECC_FAMILY_BRAINPOOL_P_R1 ); case MBEDTLS_ECP_DP_BP512R1: *bits = 512; return( PSA_ECC_FAMILY_BRAINPOOL_P_R1 ); case MBEDTLS_ECP_DP_CURVE25519: *bits = 255; return( PSA_ECC_FAMILY_MONTGOMERY ); case MBEDTLS_ECP_DP_SECP192K1: *bits = 192; return( PSA_ECC_FAMILY_SECP_K1 ); case MBEDTLS_ECP_DP_SECP224K1: *bits = 224; return( PSA_ECC_FAMILY_SECP_K1 ); case MBEDTLS_ECP_DP_SECP256K1: *bits = 256; return( PSA_ECC_FAMILY_SECP_K1 ); case MBEDTLS_ECP_DP_CURVE448: *bits = 448; return( PSA_ECC_FAMILY_MONTGOMERY ); default: *bits = 0; return( 0 ); } } /** Convert an ECC curve identifier from the PSA encoding to Mbed TLS. * * \note This function is provided solely for the convenience of * Mbed TLS and may be removed at any time without notice. * * \param curve A PSA elliptic curve identifier * (`PSA_ECC_FAMILY_xxx`). * \param byte_length The byte-length of a private key on \p curve. * * \return The corresponding Mbed TLS elliptic curve identifier * (`MBEDTLS_ECP_DP_xxx`). * \return #MBEDTLS_ECP_DP_NONE if \c curve is not recognized. * \return #MBEDTLS_ECP_DP_NONE if \p byte_length is not * correct for \p curve. */ mbedtls_ecp_group_id mbedtls_ecc_group_of_psa( psa_ecc_family_t curve, size_t byte_length ); #endif /* MBEDTLS_ECP_C */ /**@}*/ /** \defgroup psa_external_rng External random generator * @{ */ #if defined(MBEDTLS_PSA_CRYPTO_EXTERNAL_RNG) /** External random generator function, implemented by the platform. * * When the compile-time option #MBEDTLS_PSA_CRYPTO_EXTERNAL_RNG is enabled, * this function replaces Mbed TLS's entropy and DRBG modules for all * random generation triggered via PSA crypto interfaces. * * \note This random generator must deliver random numbers with cryptographic * quality and high performance. It must supply unpredictable numbers * with a uniform distribution. The implementation of this function * is responsible for ensuring that the random generator is seeded * with sufficient entropy. If you have a hardware TRNG which is slow * or delivers non-uniform output, declare it as an entropy source * with mbedtls_entropy_add_source() instead of enabling this option. * * \param[in,out] context Pointer to the random generator context. * This is all-bits-zero on the first call * and preserved between successive calls. * \param[out] output Output buffer. On success, this buffer * contains random data with a uniform * distribution. * \param output_size The size of the \p output buffer in bytes. * \param[out] output_length On success, set this value to \p output_size. * * \retval #PSA_SUCCESS * Success. The output buffer contains \p output_size bytes of * cryptographic-quality random data, and \c *output_length is * set to \p output_size. * \retval #PSA_ERROR_INSUFFICIENT_ENTROPY * The random generator requires extra entropy and there is no * way to obtain entropy under current environment conditions. * This error should not happen under normal circumstances since * this function is responsible for obtaining as much entropy as * it needs. However implementations of this function may return * #PSA_ERROR_INSUFFICIENT_ENTROPY if there is no way to obtain * entropy without blocking indefinitely. * \retval #PSA_ERROR_HARDWARE_FAILURE * A failure of the random generator hardware that isn't covered * by #PSA_ERROR_INSUFFICIENT_ENTROPY. */ psa_status_t mbedtls_psa_external_get_random( mbedtls_psa_external_random_context_t *context, uint8_t *output, size_t output_size, size_t *output_length ); #endif /* MBEDTLS_PSA_CRYPTO_EXTERNAL_RNG */ /**@}*/ #ifdef __cplusplus } #endif #endif /* PSA_CRYPTO_EXTRA_H */