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Diffstat (limited to 'library/psa_crypto_random_impl.h')
| -rw-r--r-- | library/psa_crypto_random_impl.h | 205 |
1 files changed, 205 insertions, 0 deletions
diff --git a/library/psa_crypto_random_impl.h b/library/psa_crypto_random_impl.h new file mode 100644 index 000000000..3c4c09a28 --- /dev/null +++ b/library/psa_crypto_random_impl.h @@ -0,0 +1,205 @@ +/** \file psa_crypto_random_impl.h + * + * \brief PSA crypto random generator implementation abstraction. + * + * The definitions here need to be consistent with the declarations + * in include/mbedtls/psa_util.h. This file contains some redundant + * declarations to increase the chance that a compiler will detect + * inconsistencies if one file is changed without updating the other, + * but not all potential inconsistencies can be enforced, so make sure + * to check the public declarations and contracts in + * include/mbedtls/psa_util.h if you modify this file. + */ +/* + * 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 + +#include <mbedtls/psa_util.h> + +#if defined(MBEDTLS_PSA_CRYPTO_EXTERNAL_RNG) + +#include <string.h> +#include <mbedtls/entropy.h> // only for error codes +#include <psa/crypto.h> + +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 <limits.h> +#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" + +/** 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; + +/* Defined in include/mbedtls/psa_util.h so that it's visible to + * application code. The declaration here is redundant, but included + * as a safety net to make it more likely that a future change that + * accidentally causes the implementation to diverge from the interface + * will be noticed. */ +/* Do not include the declaration under MSVC because it doesn't accept it + * ("error C2370: 'mbedtls_psa_get_random' : redefinition; different storage class"). + * Observed with Visual Studio 2013. A known bug apparently: + * https://stackoverflow.com/questions/8146541/duplicate-external-static-declarations-not-allowed-in-visual-studio + */ +#if !defined(_MSC_VER) +static mbedtls_f_rng_t *const mbedtls_psa_get_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. */ +/* The type `mbedtls_psa_drbg_context_t` is defined in + * include/mbedtls/psa_util.h so that `mbedtls_psa_random_state` can be + * declared there and be visible to application code. */ +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 */ |