1 /** \file psa_crypto_random_impl.h 2 * 3 * \brief PSA crypto random generator implementation abstraction. 4 */ 5 /* 6 * Copyright The Mbed TLS Contributors 7 * SPDX-License-Identifier: Apache-2.0 OR GPL-2.0-or-later 8 */ 9 10 #ifndef PSA_CRYPTO_RANDOM_IMPL_H 11 #define PSA_CRYPTO_RANDOM_IMPL_H 12 13 #include "psa_util_internal.h" 14 15 #if defined(MBEDTLS_PSA_CRYPTO_EXTERNAL_RNG) 16 17 typedef mbedtls_psa_external_random_context_t mbedtls_psa_random_context_t; 18 19 #else /* MBEDTLS_PSA_CRYPTO_EXTERNAL_RNG */ 20 21 #include "mbedtls/entropy.h" 22 23 /* Choose a DRBG based on configuration and availability */ 24 #if defined(MBEDTLS_PSA_HMAC_DRBG_MD_TYPE) 25 26 #include "mbedtls/hmac_drbg.h" 27 28 #elif defined(MBEDTLS_CTR_DRBG_C) 29 30 #include "mbedtls/ctr_drbg.h" 31 32 #elif defined(MBEDTLS_HMAC_DRBG_C) 33 34 #include "mbedtls/hmac_drbg.h" 35 #if defined(MBEDTLS_MD_CAN_SHA512) && defined(MBEDTLS_MD_CAN_SHA256) 36 #include <limits.h> 37 #if SIZE_MAX > 0xffffffff 38 /* Looks like a 64-bit system, so prefer SHA-512. */ 39 #define MBEDTLS_PSA_HMAC_DRBG_MD_TYPE MBEDTLS_MD_SHA512 40 #else 41 /* Looks like a 32-bit system, so prefer SHA-256. */ 42 #define MBEDTLS_PSA_HMAC_DRBG_MD_TYPE MBEDTLS_MD_SHA256 43 #endif 44 #elif defined(MBEDTLS_MD_CAN_SHA512) 45 #define MBEDTLS_PSA_HMAC_DRBG_MD_TYPE MBEDTLS_MD_SHA512 46 #elif defined(MBEDTLS_MD_CAN_SHA256) 47 #define MBEDTLS_PSA_HMAC_DRBG_MD_TYPE MBEDTLS_MD_SHA256 48 #else 49 #error "No hash algorithm available for HMAC_DBRG." 50 #endif 51 52 #else /* !MBEDTLS_PSA_HMAC_DRBG_MD_TYPE && !MBEDTLS_CTR_DRBG_C && !MBEDTLS_HMAC_DRBG_C*/ 53 54 #error "No DRBG module available for the psa_crypto module." 55 56 #endif /* !MBEDTLS_PSA_HMAC_DRBG_MD_TYPE && !MBEDTLS_CTR_DRBG_C && !MBEDTLS_HMAC_DRBG_C*/ 57 58 #if defined(MBEDTLS_CTR_DRBG_C) 59 #include "mbedtls/ctr_drbg.h" 60 #elif defined(MBEDTLS_HMAC_DRBG_C) 61 #include "mbedtls/hmac_drbg.h" 62 #endif /* !MBEDTLS_CTR_DRBG_C && !MBEDTLS_HMAC_DRBG_C */ 63 64 /* The maximum number of bytes that mbedtls_psa_get_random() is expected to return. */ 65 #if defined(MBEDTLS_CTR_DRBG_C) 66 #define MBEDTLS_PSA_RANDOM_MAX_REQUEST MBEDTLS_CTR_DRBG_MAX_REQUEST 67 #elif defined(MBEDTLS_HMAC_DRBG_C) 68 #define MBEDTLS_PSA_RANDOM_MAX_REQUEST MBEDTLS_HMAC_DRBG_MAX_REQUEST 69 #endif 70 71 #if defined(MBEDTLS_CTR_DRBG_C) 72 typedef mbedtls_ctr_drbg_context mbedtls_psa_drbg_context_t; 73 #elif defined(MBEDTLS_HMAC_DRBG_C) 74 typedef mbedtls_hmac_drbg_context mbedtls_psa_drbg_context_t; 75 #endif /* !MBEDTLS_CTR_DRBG_C && !MBEDTLS_HMAC_DRBG_C */ 76 77 typedef struct { 78 void (* entropy_init)(mbedtls_entropy_context *ctx); 79 void (* entropy_free)(mbedtls_entropy_context *ctx); 80 mbedtls_entropy_context entropy; 81 mbedtls_psa_drbg_context_t drbg; 82 } mbedtls_psa_random_context_t; 83 84 /** Initialize the PSA DRBG. 85 * 86 * \param p_rng Pointer to the Mbed TLS DRBG state. 87 */ 88 static inline void mbedtls_psa_drbg_init(mbedtls_psa_drbg_context_t *p_rng) 89 { 90 #if defined(MBEDTLS_CTR_DRBG_C) 91 mbedtls_ctr_drbg_init(p_rng); 92 #elif defined(MBEDTLS_HMAC_DRBG_C) 93 mbedtls_hmac_drbg_init(p_rng); 94 #endif 95 } 96 97 /** Deinitialize the PSA DRBG. 98 * 99 * \param p_rng Pointer to the Mbed TLS DRBG state. 100 */ 101 static inline void mbedtls_psa_drbg_free(mbedtls_psa_drbg_context_t *p_rng) 102 { 103 #if defined(MBEDTLS_CTR_DRBG_C) 104 mbedtls_ctr_drbg_free(p_rng); 105 #elif defined(MBEDTLS_HMAC_DRBG_C) 106 mbedtls_hmac_drbg_free(p_rng); 107 #endif 108 } 109 110 /** Seed the PSA DRBG. 111 * 112 * \param entropy An entropy context to read the seed from. 113 * \param custom The personalization string. 114 * This can be \c NULL, in which case the personalization 115 * string is empty regardless of the value of \p len. 116 * \param len The length of the personalization string. 117 * 118 * \return \c 0 on success. 119 * \return An Mbed TLS error code (\c MBEDTLS_ERR_xxx) on failure. 120 */ 121 static inline int mbedtls_psa_drbg_seed(mbedtls_psa_drbg_context_t *drbg_ctx, 122 mbedtls_entropy_context *entropy, 123 const unsigned char *custom, size_t len) 124 { 125 #if defined(MBEDTLS_CTR_DRBG_C) 126 return mbedtls_ctr_drbg_seed(drbg_ctx, mbedtls_entropy_func, entropy, custom, len); 127 #elif defined(MBEDTLS_HMAC_DRBG_C) 128 const mbedtls_md_info_t *md_info = mbedtls_md_info_from_type(MBEDTLS_PSA_HMAC_DRBG_MD_TYPE); 129 return mbedtls_hmac_drbg_seed(drbg_ctx, md_info, mbedtls_entropy_func, entropy, custom, len); 130 #endif 131 } 132 133 #endif /* MBEDTLS_PSA_CRYPTO_EXTERNAL_RNG */ 134 135 #endif /* PSA_CRYPTO_RANDOM_IMPL_H */ 136