/** \file psa_crypto_random_impl.h
*
* \brief PSA crypto random generator implementation abstraction.
*/
/*
* Copyright The Mbed TLS Contributors
* SPDX-License-Identifier: Apache-2.0 OR GPL-2.0-or-later
*/
#ifndef PSA_CRYPTO_RANDOM_IMPL_H
#define PSA_CRYPTO_RANDOM_IMPL_H
#include "psa_util_internal.h"
#if defined(MBEDTLS_PSA_CRYPTO_EXTERNAL_RNG)
typedef mbedtls_psa_external_random_context_t mbedtls_psa_random_context_t;
#else /* MBEDTLS_PSA_CRYPTO_EXTERNAL_RNG */
#include "mbedtls/entropy.h"
/* Choose a DRBG based on configuration and availability */
#if defined(MBEDTLS_CTR_DRBG_C)
#include "mbedtls/ctr_drbg.h"
#undef MBEDTLS_PSA_HMAC_DRBG_MD_TYPE
#elif defined(MBEDTLS_HMAC_DRBG_C)
#include "mbedtls/hmac_drbg.h"
#if defined(MBEDTLS_MD_CAN_SHA512) && defined(MBEDTLS_MD_CAN_SHA256)
#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_MD_CAN_SHA512)
#define MBEDTLS_PSA_HMAC_DRBG_MD_TYPE MBEDTLS_MD_SHA512
#elif defined(MBEDTLS_MD_CAN_SHA256)
#define MBEDTLS_PSA_HMAC_DRBG_MD_TYPE MBEDTLS_MD_SHA256
#else
#error "No hash algorithm available for HMAC_DBRG."
#endif
#else /* !MBEDTLS_CTR_DRBG_C && !MBEDTLS_HMAC_DRBG_C*/
#error "No DRBG module available for the psa_crypto module."
#endif /* !MBEDTLS_CTR_DRBG_C && !MBEDTLS_HMAC_DRBG_C*/
/* 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
#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 /* !MBEDTLS_CTR_DRBG_C && !MBEDTLS_HMAC_DRBG_C */
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;
/** 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
}
/** 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_psa_drbg_context_t *drbg_ctx,
mbedtls_entropy_context *entropy,
const unsigned char *custom, size_t len)
{
#if defined(MBEDTLS_CTR_DRBG_C)
return mbedtls_ctr_drbg_seed(drbg_ctx, 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(drbg_ctx, md_info, mbedtls_entropy_func, entropy, custom, len);
#endif
}
#endif /* MBEDTLS_PSA_CRYPTO_EXTERNAL_RNG */
#endif /* PSA_CRYPTO_RANDOM_IMPL_H */
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