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
17typedef 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)
72typedef mbedtls_ctr_drbg_context            mbedtls_psa_drbg_context_t;
73#elif defined(MBEDTLS_HMAC_DRBG_C)
74typedef mbedtls_hmac_drbg_context           mbedtls_psa_drbg_context_t;
75#endif /* !MBEDTLS_CTR_DRBG_C && !MBEDTLS_HMAC_DRBG_C */
76
77typedef 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 */
88static 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 */
101static 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 */
121static 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