mirror of
https://github.com/espressif/mbedtls.git
synced 2026-06-05 21:14:47 +00:00
Ashish Sharma
216 lines
7.8 KiB
C
216 lines
7.8 KiB
C
/** \file psa_crypto_random_impl.h
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*
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* \brief PSA crypto random generator implementation abstraction.
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*/
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/*
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* Copyright The Mbed TLS Contributors
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* SPDX-License-Identifier: Apache-2.0 OR GPL-2.0-or-later
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*/
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#ifndef TF_PSA_CRYPTO_PSA_CRYPTO_RANDOM_IMPL_H
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#define TF_PSA_CRYPTO_PSA_CRYPTO_RANDOM_IMPL_H
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#include "mbedtls/psa_util.h"
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#if defined(MBEDTLS_PSA_CRYPTO_EXTERNAL_RNG)
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typedef mbedtls_psa_external_random_context_t mbedtls_psa_random_context_t;
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#else /* MBEDTLS_PSA_CRYPTO_EXTERNAL_RNG */
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#include "mbedtls/private/entropy.h"
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#include "mbedtls/private/error_common.h"
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#if !defined(PSA_WANT_ALG_SHA_256)
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MBEDTLS_STATIC_ASSERT(MBEDTLS_PSA_CRYPTO_RNG_HASH != PSA_ALG_SHA_256,
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"SHA_256 used as the hash for the random generator, but not enabled");
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#endif
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#if !defined(PSA_WANT_ALG_SHA_512)
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MBEDTLS_STATIC_ASSERT(MBEDTLS_PSA_CRYPTO_RNG_HASH != PSA_ALG_SHA_512,
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"SHA_512 used as the hash for the random generator, but not enabled");
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#endif
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MBEDTLS_STATIC_ASSERT((MBEDTLS_PSA_CRYPTO_RNG_HASH == PSA_ALG_SHA_256) || \
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(MBEDTLS_PSA_CRYPTO_RNG_HASH == PSA_ALG_SHA_512),
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"Invalid hashing algorithm for MBEDTLS_PSA_CRYPTO_RNG_HASH");
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MBEDTLS_STATIC_ASSERT(PSA_BYTES_TO_BITS(PSA_HASH_LENGTH(
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MBEDTLS_PSA_CRYPTO_RNG_HASH))
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>= MBEDTLS_PSA_CRYPTO_RNG_STRENGTH,
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"The hash size (in bits) of MBEDTLS_PSA_CRYPTO_RNG_HASH must be at least MBEDTLS_PSA_CRYPTO_RNG_STRENGTH");
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/* Choose a DRBG based on configuration and availability */
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#if defined(MBEDTLS_CTR_DRBG_C)
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#include "mbedtls/private/ctr_drbg.h"
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#if (MBEDTLS_PSA_CRYPTO_RNG_STRENGTH > 128) && \
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defined(MBEDTLS_AES_ONLY_128_BIT_KEY_LENGTH)
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#error "CTR_DRBG cannot meet the configured RNG strength using only 128-bit AES keys."
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#endif
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#if MBEDTLS_PSA_CRYPTO_RNG_STRENGTH > PSA_BYTES_TO_BITS(MBEDTLS_CTR_DRBG_KEYSIZE)
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#error "The CTR_DRBG key size (in bits) must be at least MBEDTLS_PSA_CRYPTO_RNG_STRENGTH"
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#endif
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#undef MBEDTLS_PSA_HMAC_DRBG_MD_TYPE
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#elif defined(MBEDTLS_HMAC_DRBG_C)
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#include "mbedtls/private/hmac_drbg.h"
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#define MBEDTLS_PSA_HMAC_DRBG_MD_TYPE MBEDTLS_ENTROPY_MD
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#else /* !MBEDTLS_CTR_DRBG_C && !MBEDTLS_HMAC_DRBG_C*/
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#error "No DRBG module available for the psa_crypto module."
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#endif /* !MBEDTLS_CTR_DRBG_C && !MBEDTLS_HMAC_DRBG_C*/
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/* The maximum number of bytes that mbedtls_psa_get_random() is expected to return. */
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#if defined(MBEDTLS_CTR_DRBG_C)
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#define MBEDTLS_PSA_RANDOM_MAX_REQUEST MBEDTLS_CTR_DRBG_MAX_REQUEST
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#elif defined(MBEDTLS_HMAC_DRBG_C)
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#define MBEDTLS_PSA_RANDOM_MAX_REQUEST MBEDTLS_HMAC_DRBG_MAX_REQUEST
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#endif
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#if defined(MBEDTLS_CTR_DRBG_C)
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typedef mbedtls_ctr_drbg_context mbedtls_psa_drbg_context_t;
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#elif defined(MBEDTLS_HMAC_DRBG_C)
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typedef mbedtls_hmac_drbg_context mbedtls_psa_drbg_context_t;
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#endif /* !MBEDTLS_CTR_DRBG_C && !MBEDTLS_HMAC_DRBG_C */
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typedef struct {
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void (* entropy_init)(mbedtls_entropy_context *ctx);
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void (* entropy_free)(mbedtls_entropy_context *ctx);
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mbedtls_entropy_context entropy;
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mbedtls_psa_drbg_context_t drbg;
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#if defined(MBEDTLS_PLATFORM_IS_UNIXLIKE)
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/* Fork protection: normally pid = getpid(). If the value changes,
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* we are in a (grand)*child of the original process, so reseed
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* the RNG to ensure that the child and the original process have
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* distinct RNG states. See psa_random_internal_generate().
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*
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* The type is intmax_t, not pid_t, for portability reasons:
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* pid_t is defined in `unistd.h`, but on some platforms, it may
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* only be defined if a certain compatibility level is requested
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* by defining a macro such as _POSIX_C_SOURCE or _XOPEN_SOURCE.
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* The macro needs to be defined before any system header, which
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* may be hard to do in some C files that include this header
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* (e.g. test suites). So we sidestep this complication, at the
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* cost of possibly a few more instructions to compare pid values.
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*/
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intmax_t pid;
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#endif
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} mbedtls_psa_random_context_t;
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/** Initialize the PSA DRBG.
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*
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* \param p_rng Pointer to the Mbed TLS DRBG state.
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*/
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static inline void mbedtls_psa_drbg_init(mbedtls_psa_drbg_context_t *p_rng)
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{
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#if defined(MBEDTLS_CTR_DRBG_C)
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mbedtls_ctr_drbg_init(p_rng);
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#elif defined(MBEDTLS_HMAC_DRBG_C)
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mbedtls_hmac_drbg_init(p_rng);
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#endif
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}
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/** Deinitialize the PSA DRBG.
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*
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* \param p_rng Pointer to the Mbed TLS DRBG state.
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*/
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static inline void mbedtls_psa_drbg_free(mbedtls_psa_drbg_context_t *p_rng)
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{
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#if defined(MBEDTLS_CTR_DRBG_C)
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mbedtls_ctr_drbg_free(p_rng);
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#elif defined(MBEDTLS_HMAC_DRBG_C)
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mbedtls_hmac_drbg_free(p_rng);
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#endif
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}
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/** Seed the PSA DRBG.
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*
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* \param drbg_ctx The DRBG context to seed.
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* It must be initialized but not active.
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* \param entropy An entropy context to read the seed from.
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* \param custom The personalization string.
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* This can be \c NULL, in which case the personalization
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* string is empty regardless of the value of \p len.
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* \param len The length of the personalization string.
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*
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* \return \c 0 on success.
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* \return An Mbed TLS error code (\c MBEDTLS_ERR_xxx) on failure.
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*/
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static inline int mbedtls_psa_drbg_seed(mbedtls_psa_drbg_context_t *drbg_ctx,
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mbedtls_entropy_context *entropy,
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const unsigned char *custom, size_t len)
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{
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#if defined(MBEDTLS_CTR_DRBG_C)
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return mbedtls_ctr_drbg_seed(drbg_ctx, mbedtls_entropy_func, entropy, custom, len);
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#elif defined(MBEDTLS_HMAC_DRBG_C)
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const mbedtls_md_info_t *md_info = mbedtls_md_info_from_type(MBEDTLS_PSA_HMAC_DRBG_MD_TYPE);
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return mbedtls_hmac_drbg_seed(drbg_ctx, md_info, mbedtls_entropy_func, entropy, custom, len);
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#endif /* MBEDTLS_HMAC_DRBG_C */
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}
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/** Reseed the PSA DRBG.
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*
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* \param drbg_ctx The DRBG context to reseed.
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* It must be active.
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* \param additional Additional data to inject.
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* \param len The length of \p additional in bytes.
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* This can be 0 to simply reseed from the entropy source.
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*
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* \return \c 0 on success.
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* \return An Mbed TLS error code (\c MBEDTLS_ERR_xxx) on failure.
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*/
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static inline int mbedtls_psa_drbg_reseed(mbedtls_psa_drbg_context_t *drbg_ctx,
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const unsigned char *additional,
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size_t len)
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{
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#if defined(MBEDTLS_CTR_DRBG_C)
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return mbedtls_ctr_drbg_reseed(drbg_ctx, additional, len);
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#elif defined(MBEDTLS_HMAC_DRBG_C)
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return mbedtls_hmac_drbg_reseed(drbg_ctx, additional, len);
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#endif
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}
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/** Deplete the PSA DRBG, i.e. cause it to reseed the next time it is used.
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*
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* \note This function is not thread-safe.
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*
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* \param drbg_ctx The DRBG context to deplete.
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* It must be active.
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*/
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static inline void mbedtls_psa_drbg_deplete(mbedtls_psa_drbg_context_t *drbg_ctx)
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{
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drbg_ctx->reseed_counter = drbg_ctx->reseed_interval;
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}
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#if MBEDTLS_ENTROPY_TRUE_SOURCES > 0
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/** Set prediction resistance in the PSA DRBG.
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*
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* \note This function is not thread-safe.
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*
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* \param drbg_ctx The DRBG context to reconfigure.
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* It must be active.
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* \param enabled \c 1 to enable, or \c 0 to disable.
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*/
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static inline void mbedtls_psa_drbg_set_prediction_resistance(
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mbedtls_psa_drbg_context_t *drbg_ctx,
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unsigned enabled)
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{
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#if defined(MBEDTLS_CTR_DRBG_C)
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mbedtls_ctr_drbg_set_prediction_resistance(drbg_ctx, enabled);
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#elif defined(MBEDTLS_HMAC_DRBG_C)
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mbedtls_hmac_drbg_set_prediction_resistance(drbg_ctx, enabled);
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#endif
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}
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#endif /* MBEDTLS_ENTROPY_TRUE_SOURCES > 0 */
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#endif /* MBEDTLS_PSA_CRYPTO_EXTERNAL_RNG */
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#endif /* TF_PSA_CRYPTO_PSA_CRYPTO_RANDOM_IMPL_H */
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