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_CTR_DRBG_C)
25
26 #include "mbedtls/ctr_drbg.h"
27 #undef MBEDTLS_PSA_HMAC_DRBG_MD_TYPE
28
29 #elif defined(MBEDTLS_HMAC_DRBG_C)
30
31 #include "mbedtls/hmac_drbg.h"
32 #if defined(MBEDTLS_MD_CAN_SHA512) && defined(MBEDTLS_MD_CAN_SHA256)
33 #include <limits.h>
34 #if SIZE_MAX > 0xffffffff
35 /* Looks like a 64-bit system, so prefer SHA-512. */
36 #define MBEDTLS_PSA_HMAC_DRBG_MD_TYPE MBEDTLS_MD_SHA512
37 #else
38 /* Looks like a 32-bit system, so prefer SHA-256. */
39 #define MBEDTLS_PSA_HMAC_DRBG_MD_TYPE MBEDTLS_MD_SHA256
40 #endif
41 #elif defined(MBEDTLS_MD_CAN_SHA512)
42 #define MBEDTLS_PSA_HMAC_DRBG_MD_TYPE MBEDTLS_MD_SHA512
43 #elif defined(MBEDTLS_MD_CAN_SHA256)
44 #define MBEDTLS_PSA_HMAC_DRBG_MD_TYPE MBEDTLS_MD_SHA256
45 #else
46 #error "No hash algorithm available for HMAC_DBRG."
47 #endif
48
49 #else /* !MBEDTLS_CTR_DRBG_C && !MBEDTLS_HMAC_DRBG_C*/
50
51 #error "No DRBG module available for the psa_crypto module."
52
53 #endif /* !MBEDTLS_CTR_DRBG_C && !MBEDTLS_HMAC_DRBG_C*/
54
55 /* The maximum number of bytes that mbedtls_psa_get_random() is expected to return. */
56 #if defined(MBEDTLS_CTR_DRBG_C)
57 #define MBEDTLS_PSA_RANDOM_MAX_REQUEST MBEDTLS_CTR_DRBG_MAX_REQUEST
58 #elif defined(MBEDTLS_HMAC_DRBG_C)
59 #define MBEDTLS_PSA_RANDOM_MAX_REQUEST MBEDTLS_HMAC_DRBG_MAX_REQUEST
60 #endif
61
62 #if defined(MBEDTLS_CTR_DRBG_C)
63 typedef mbedtls_ctr_drbg_context mbedtls_psa_drbg_context_t;
64 #elif defined(MBEDTLS_HMAC_DRBG_C)
65 typedef mbedtls_hmac_drbg_context mbedtls_psa_drbg_context_t;
66 #endif /* !MBEDTLS_CTR_DRBG_C && !MBEDTLS_HMAC_DRBG_C */
67
68 typedef struct {
69 void (* entropy_init)(mbedtls_entropy_context *ctx);
70 void (* entropy_free)(mbedtls_entropy_context *ctx);
71 mbedtls_entropy_context entropy;
72 mbedtls_psa_drbg_context_t drbg;
73 } mbedtls_psa_random_context_t;
74
75 /** Initialize the PSA DRBG.
76 *
77 * \param p_rng Pointer to the Mbed TLS DRBG state.
78 */
mbedtls_psa_drbg_init(mbedtls_psa_drbg_context_t * p_rng)79 static inline void mbedtls_psa_drbg_init(mbedtls_psa_drbg_context_t *p_rng)
80 {
81 #if defined(MBEDTLS_CTR_DRBG_C)
82 mbedtls_ctr_drbg_init(p_rng);
83 #elif defined(MBEDTLS_HMAC_DRBG_C)
84 mbedtls_hmac_drbg_init(p_rng);
85 #endif
86 }
87
88 /** Deinitialize the PSA DRBG.
89 *
90 * \param p_rng Pointer to the Mbed TLS DRBG state.
91 */
mbedtls_psa_drbg_free(mbedtls_psa_drbg_context_t * p_rng)92 static inline void mbedtls_psa_drbg_free(mbedtls_psa_drbg_context_t *p_rng)
93 {
94 #if defined(MBEDTLS_CTR_DRBG_C)
95 mbedtls_ctr_drbg_free(p_rng);
96 #elif defined(MBEDTLS_HMAC_DRBG_C)
97 mbedtls_hmac_drbg_free(p_rng);
98 #endif
99 }
100
101 /** Seed the PSA DRBG.
102 *
103 * \param entropy An entropy context to read the seed from.
104 * \param custom The personalization string.
105 * This can be \c NULL, in which case the personalization
106 * string is empty regardless of the value of \p len.
107 * \param len The length of the personalization string.
108 *
109 * \return \c 0 on success.
110 * \return An Mbed TLS error code (\c MBEDTLS_ERR_xxx) on failure.
111 */
mbedtls_psa_drbg_seed(mbedtls_psa_drbg_context_t * drbg_ctx,mbedtls_entropy_context * entropy,const unsigned char * custom,size_t len)112 static inline int mbedtls_psa_drbg_seed(mbedtls_psa_drbg_context_t *drbg_ctx,
113 mbedtls_entropy_context *entropy,
114 const unsigned char *custom, size_t len)
115 {
116 #if defined(MBEDTLS_CTR_DRBG_C)
117 return mbedtls_ctr_drbg_seed(drbg_ctx, mbedtls_entropy_func, entropy, custom, len);
118 #elif defined(MBEDTLS_HMAC_DRBG_C)
119 const mbedtls_md_info_t *md_info = mbedtls_md_info_from_type(MBEDTLS_PSA_HMAC_DRBG_MD_TYPE);
120 return mbedtls_hmac_drbg_seed(drbg_ctx, md_info, mbedtls_entropy_func, entropy, custom, len);
121 #endif
122 }
123
124 #endif /* MBEDTLS_PSA_CRYPTO_EXTERNAL_RNG */
125
126 #endif /* PSA_CRYPTO_RANDOM_IMPL_H */
127
