gbe_fork/mbedtls/psa_crypto_random_impl.h
2023-12-24 14:33:40 +02:00

193 lines
6.4 KiB
C

/** \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/psa_util_internal.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/psa_util_internal.h if you modify this file.
*/
/*
* 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)
#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_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
#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/psa_util_internal.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/psa_util_internal.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 */