ctr_drbg.h

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/*
 *  Copyright The Mbed TLS Contributors
 *  SPDX-License-Identifier: Apache-2.0 OR GPL-2.0-or-later
 */

#ifndef MBEDTLS_CTR_DRBG_H
#define MBEDTLS_CTR_DRBG_H
#include "mbedtls/private_access.h"

#include "mbedtls/build_info.h"

/* The CTR_DRBG implementation can either directly call the low-level AES
 * module (gated by MBEDTLS_AES_C) or call the PSA API to perform AES
 * operations. Calling the AES module directly is the default, both for
 * maximum backward compatibility and because it's a bit more efficient
 * (less glue code).
 *
 * When MBEDTLS_AES_C is disabled, the CTR_DRBG module calls PSA crypto and
 * thus benefits from the PSA AES accelerator driver.
 * It is technically possible to enable MBEDTLS_CTR_DRBG_USE_PSA_CRYPTO
 * to use PSA even when MBEDTLS_AES_C is enabled, but there is very little
 * reason to do so other than testing purposes and this is not officially
 * supported.
 */
#if !defined(MBEDTLS_AES_C)
#define MBEDTLS_CTR_DRBG_USE_PSA_CRYPTO
#endif

#if defined(MBEDTLS_CTR_DRBG_USE_PSA_CRYPTO)
#include "psa/crypto.h"
#else
#include "mbedtls/aes.h"
#endif

#include "entropy.h"

#if defined(MBEDTLS_THREADING_C)
#include "mbedtls/threading.h"
#endif

#define MBEDTLS_ERR_CTR_DRBG_ENTROPY_SOURCE_FAILED        -0x0034

#define MBEDTLS_ERR_CTR_DRBG_REQUEST_TOO_BIG              -0x0036

#define MBEDTLS_ERR_CTR_DRBG_INPUT_TOO_BIG                -0x0038

#define MBEDTLS_ERR_CTR_DRBG_FILE_IO_ERROR                -0x003A

#define MBEDTLS_CTR_DRBG_BLOCKSIZE          16 
#if defined(MBEDTLS_CTR_DRBG_USE_128_BIT_KEY)
#define MBEDTLS_CTR_DRBG_KEYSIZE            16

#else
#define MBEDTLS_CTR_DRBG_KEYSIZE            32

#endif

#define MBEDTLS_CTR_DRBG_KEYBITS            (MBEDTLS_CTR_DRBG_KEYSIZE * 8)   
#define MBEDTLS_CTR_DRBG_SEEDLEN            (MBEDTLS_CTR_DRBG_KEYSIZE + MBEDTLS_CTR_DRBG_BLOCKSIZE)   
#if !defined(MBEDTLS_CTR_DRBG_ENTROPY_LEN)
#if defined(MBEDTLS_ENTROPY_SHA512_ACCUMULATOR)

#define MBEDTLS_CTR_DRBG_ENTROPY_LEN        48

#else /* MBEDTLS_ENTROPY_SHA512_ACCUMULATOR */

#if !defined(MBEDTLS_CTR_DRBG_USE_128_BIT_KEY)

#endif /* !defined(MBEDTLS_CTR_DRBG_USE_128_BIT_KEY) */
#define MBEDTLS_CTR_DRBG_ENTROPY_LEN        32
#endif /* MBEDTLS_ENTROPY_SHA512_ACCUMULATOR */
#endif /* !defined(MBEDTLS_CTR_DRBG_ENTROPY_LEN) */

#if !defined(MBEDTLS_CTR_DRBG_RESEED_INTERVAL)
#define MBEDTLS_CTR_DRBG_RESEED_INTERVAL    10000

#endif

#if !defined(MBEDTLS_CTR_DRBG_MAX_INPUT)
#define MBEDTLS_CTR_DRBG_MAX_INPUT          256

#endif

#if !defined(MBEDTLS_CTR_DRBG_MAX_REQUEST)
#define MBEDTLS_CTR_DRBG_MAX_REQUEST        1024

#endif

#if !defined(MBEDTLS_CTR_DRBG_MAX_SEED_INPUT)
#define MBEDTLS_CTR_DRBG_MAX_SEED_INPUT     384

#endif

#define MBEDTLS_CTR_DRBG_PR_OFF             0

#define MBEDTLS_CTR_DRBG_PR_ON              1

#ifdef __cplusplus
extern "C" {
#endif

#if MBEDTLS_CTR_DRBG_ENTROPY_LEN >= MBEDTLS_CTR_DRBG_KEYSIZE * 3 / 2

#define MBEDTLS_CTR_DRBG_ENTROPY_NONCE_LEN 0
#else

#define MBEDTLS_CTR_DRBG_ENTROPY_NONCE_LEN (MBEDTLS_CTR_DRBG_ENTROPY_LEN + 1) / 2
#endif

#if defined(MBEDTLS_CTR_DRBG_USE_PSA_CRYPTO)
typedef struct mbedtls_ctr_drbg_psa_context {
    mbedtls_svc_key_id_t key_id;
    psa_cipher_operation_t operation;
} mbedtls_ctr_drbg_psa_context;
#endif

typedef struct mbedtls_ctr_drbg_context {
    unsigned char MBEDTLS_PRIVATE(counter)[16];  
    int MBEDTLS_PRIVATE(reseed_counter);         
    int MBEDTLS_PRIVATE(prediction_resistance);  
    size_t MBEDTLS_PRIVATE(entropy_len);         
    int MBEDTLS_PRIVATE(reseed_interval);        
#if defined(MBEDTLS_CTR_DRBG_USE_PSA_CRYPTO)
    mbedtls_ctr_drbg_psa_context MBEDTLS_PRIVATE(psa_ctx); 
#else
    mbedtls_aes_context MBEDTLS_PRIVATE(aes_ctx);        
#endif

    /*
     * Callbacks (Entropy)
     */
    int(*MBEDTLS_PRIVATE(f_entropy))(void *, unsigned char *, size_t);
    void *MBEDTLS_PRIVATE(p_entropy);            
#if defined(MBEDTLS_THREADING_C)
    /* Invariant: the mutex is initialized if and only if f_entropy != NULL.
     * This means that the mutex is initialized during the initial seeding
     * in mbedtls_ctr_drbg_seed() and freed in mbedtls_ctr_drbg_free().
     *
     * Note that this invariant may change without notice. Do not rely on it
     * and do not access the mutex directly in application code.
     */
    mbedtls_threading_mutex_t MBEDTLS_PRIVATE(mutex);
#endif
}
mbedtls_ctr_drbg_context;

void mbedtls_ctr_drbg_init(mbedtls_ctr_drbg_context *ctx);

#if MBEDTLS_CTR_DRBG_ENTROPY_NONCE_LEN == 0

#else

#endif
#if defined(MBEDTLS_THREADING_C)

#endif /* MBEDTLS_THREADING_C */

int mbedtls_ctr_drbg_seed(mbedtls_ctr_drbg_context *ctx,
                          int (*f_entropy)(void *, unsigned char *, size_t),
                          void *p_entropy,
                          const unsigned char *custom,
                          size_t len);

void mbedtls_ctr_drbg_free(mbedtls_ctr_drbg_context *ctx);

void mbedtls_ctr_drbg_set_prediction_resistance(mbedtls_ctr_drbg_context *ctx,
                                                int resistance);

void mbedtls_ctr_drbg_set_entropy_len(mbedtls_ctr_drbg_context *ctx,
                                      size_t len);

int mbedtls_ctr_drbg_set_nonce_len(mbedtls_ctr_drbg_context *ctx,
                                   size_t len);

void mbedtls_ctr_drbg_set_reseed_interval(mbedtls_ctr_drbg_context *ctx,
                                          int interval);

int mbedtls_ctr_drbg_reseed(mbedtls_ctr_drbg_context *ctx,
                            const unsigned char *additional, size_t len);

int mbedtls_ctr_drbg_update(mbedtls_ctr_drbg_context *ctx,
                            const unsigned char *additional,
                            size_t add_len);

int mbedtls_ctr_drbg_random_with_add(void *p_rng,
                                     unsigned char *output, size_t output_len,
                                     const unsigned char *additional, size_t add_len);

#if defined(MBEDTLS_THREADING_C)

#endif /* MBEDTLS_THREADING_C */

int mbedtls_ctr_drbg_random(void *p_rng,
                            unsigned char *output, size_t output_len);

#if defined(MBEDTLS_FS_IO)

int mbedtls_ctr_drbg_write_seed_file(mbedtls_ctr_drbg_context *ctx, const char *path);

int mbedtls_ctr_drbg_update_seed_file(mbedtls_ctr_drbg_context *ctx, const char *path);
#endif /* MBEDTLS_FS_IO */

#if defined(MBEDTLS_SELF_TEST)

int mbedtls_ctr_drbg_self_test(int verbose);

#endif /* MBEDTLS_SELF_TEST */

#ifdef __cplusplus
}
#endif

#endif /* ctr_drbg.h */