/** \file psa_crypto_random_impl.h * * \brief PSA crypto random generator implementation abstraction. */ /* * 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_RANDOM_IMPL_H #define PSA_CRYPTO_RANDOM_IMPL_H #if defined(MBEDTLS_PSA_CRYPTO_EXTERNAL_RNG) #include #include // only for error codes #include typedef mbedtls_psa_external_random_context_t mbedtls_psa_random_context_t; /* Trivial wrapper around psa_generate_random(). */ int mbedtls_psa_get_random( void *p_rng, unsigned char *output, size_t output_size ); /* The PSA RNG API doesn't need any externally maintained state. */ #define MBEDTLS_PSA_RANDOM_STATE NULL #else /* MBEDTLS_PSA_CRYPTO_EXTERNAL_RNG */ /* Choose a DRBG based on configuration and availability */ #if defined(MBEDTLS_PSA_HMAC_DRBG_MD_TYPE) #include "mbedtls/hmac_drbg.h" #elif defined(MBEDTLS_CTR_DRBG_C) #include "mbedtls/ctr_drbg.h" #elif defined(MBEDTLS_HMAC_DRBG_C) #include "mbedtls/hmac_drbg.h" #if defined(MBEDTLS_SHA512_C) && defined(MBEDTLS_SHA256_C) #include #if SIZE_MAX > 0xffffffff /* Looks like a 64-bit system, so prefer SHA-512. */ #define MBEDTLS_PSA_HMAC_DRBG_MD_TYPE MBEDTLS_MD_SHA512 #else /* Looks like a 32-bit system, so prefer SHA-256. */ #define MBEDTLS_PSA_HMAC_DRBG_MD_TYPE MBEDTLS_MD_SHA256 #endif #elif defined(MBEDTLS_SHA512_C) #define MBEDTLS_PSA_HMAC_DRBG_MD_TYPE MBEDTLS_MD_SHA512 #elif defined(MBEDTLS_SHA256_C) #define MBEDTLS_PSA_HMAC_DRBG_MD_TYPE MBEDTLS_MD_SHA256 #else #error "No hash algorithm available for HMAC_DBRG." #endif #else #error "No DRBG module available for the psa_crypto module." #endif #include "mbedtls/entropy.h" /** The type of the PSA DRBG context. */ #if defined(MBEDTLS_CTR_DRBG_C) typedef mbedtls_ctr_drbg_context mbedtls_psa_drbg_context_t; #elif defined(MBEDTLS_HMAC_DRBG_C) typedef mbedtls_hmac_drbg_context mbedtls_psa_drbg_context_t; #endif /** Initialize the PSA DRBG. * * \param p_rng Pointer to the Mbed TLS DRBG state. */ static inline void mbedtls_psa_drbg_init( mbedtls_psa_drbg_context_t *p_rng ) { #if defined(MBEDTLS_CTR_DRBG_C) mbedtls_ctr_drbg_init( p_rng ); #elif defined(MBEDTLS_HMAC_DRBG_C) mbedtls_hmac_drbg_init( p_rng ); #endif } /** Deinitialize the PSA DRBG. * * \param p_rng Pointer to the Mbed TLS DRBG state. */ static inline void mbedtls_psa_drbg_free( mbedtls_psa_drbg_context_t *p_rng ) { #if defined(MBEDTLS_CTR_DRBG_C) mbedtls_ctr_drbg_free( p_rng ); #elif defined(MBEDTLS_HMAC_DRBG_C) mbedtls_hmac_drbg_free( p_rng ); #endif } /** The type of the PSA random generator context. * * The random generator context is composed of an entropy context and * a DRBG context. */ typedef struct { void (* entropy_init )( mbedtls_entropy_context *ctx ); void (* entropy_free )( mbedtls_entropy_context *ctx ); mbedtls_entropy_context entropy; mbedtls_psa_drbg_context_t drbg; } mbedtls_psa_random_context_t; /* The type of an Mbed TLS random generator function. This should be * part of the public API instead of repeating the type everywhere. * For the time being, declare it here. Declaring a type is necessary * to define mbedtls_psa_get_random as a variable of a function pointer * type without incurring the wrath of check-names.sh. */ typedef int mbedtls_f_rng_t( void *p_rng, unsigned char *output, size_t output_size ); /** Return random data. * * This function is suitable as the \p f_rng parameter to Mbed TLS functions * that require a random generator. Use #MBEDTLS_PSA_RANDOM_STATE to * obtain the \p p_rng parameter. * * \param p_rng The DRBG context. This must be * #MBEDTLS_PSA_RANDOM_STATE. * \param output The buffer to fill. * \param output_len The length of the buffer in bytes. * It must be at most #MBEDTLS_PSA_RANDOM_MAX_REQUEST. * * \retval \c 0 on success. * \return \c MBEDTLS_ERR_xxx_DRBG_xxx or * \c MBEDTLS_ERR_PLATFORM_xxx on failure. */ #if defined(MBEDTLS_CTR_DRBG_C) static mbedtls_f_rng_t *const mbedtls_psa_get_random = mbedtls_ctr_drbg_random; #elif defined(MBEDTLS_HMAC_DRBG_C) static mbedtls_f_rng_t *const mbedtls_psa_get_random = mbedtls_hmac_drbg_random; #endif /** The maximum number of bytes that mbedtls_psa_get_random() is expected to * return. */ #if defined(MBEDTLS_CTR_DRBG_C) #define MBEDTLS_PSA_RANDOM_MAX_REQUEST MBEDTLS_CTR_DRBG_MAX_REQUEST #elif defined(MBEDTLS_HMAC_DRBG_C) #define MBEDTLS_PSA_RANDOM_MAX_REQUEST MBEDTLS_HMAC_DRBG_MAX_REQUEST #endif /** A pointer to the PSA DRBG state. * * This variable is only intended to be used through the macro * #MBEDTLS_PSA_RANDOM_STATE. */ /* psa_crypto.c sets this variable to a pointer to the DRBG state in the * global PSA crypto state. */ extern mbedtls_psa_drbg_context_t *const mbedtls_psa_random_state; /** A pointer to the PSA DRBG state. * * This macro expands to an expression that is suitable as the \c p_rng * parameter to pass to mbedtls_psa_get_random(). * * This macro exists in all configurations where the psa_crypto module is * enabled. Its expansion depends on the configuration. */ #define MBEDTLS_PSA_RANDOM_STATE mbedtls_psa_random_state /** Seed the PSA DRBG. * * \param entropy An entropy context to read the seed from. * \param custom The personalization string. * This can be \c NULL, in which case the personalization * string is empty regardless of the value of \p len. * \param len The length of the personalization string. * * \return \c 0 on success. * \return An Mbed TLS error code (\c MBEDTLS_ERR_xxx) on failure. */ static inline int mbedtls_psa_drbg_seed( mbedtls_entropy_context *entropy, const unsigned char *custom, size_t len ) { #if defined(MBEDTLS_CTR_DRBG_C) return( mbedtls_ctr_drbg_seed( MBEDTLS_PSA_RANDOM_STATE, mbedtls_entropy_func, entropy, custom, len ) ); #elif defined(MBEDTLS_HMAC_DRBG_C) const mbedtls_md_info_t *md_info = mbedtls_md_info_from_type( MBEDTLS_PSA_HMAC_DRBG_MD_TYPE ); return( mbedtls_hmac_drbg_seed( MBEDTLS_PSA_RANDOM_STATE, md_info, mbedtls_entropy_func, entropy, custom, len ) ); #endif } #endif /* MBEDTLS_PSA_CRYPTO_EXTERNAL_RNG */ #endif /* PSA_CRYPTO_RANDOM_IMPL_H */