lc_hash_drbg.h

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/*
 * Copyright (C) 2022 - 2025, Stephan Mueller <smueller@chronox.de>
 *
 * License: see LICENSE file in root directory
 *
 * THIS SOFTWARE IS PROVIDED ``AS IS'' AND ANY EXPRESS OR IMPLIED
 * WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE, ALL OF
 * WHICH ARE HEREBY DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR BE
 * LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
 * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT
 * OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR
 * BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF
 * LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE
 * USE OF THIS SOFTWARE, EVEN IF NOT ADVISED OF THE POSSIBILITY OF SUCH
 * DAMAGE.
 */
 
#ifndef LC_HASH_DRBG_H
#define LC_HASH_DRBG_H
 
#include "lc_drbg.h"
#include "lc_rng.h"
#include "lc_sha512.h"
 
#ifdef __cplusplus
extern "C" {
#endif

#define LC_DRBG_HASH_STATELEN 111
#define LC_DRBG_HASH_BLOCKLEN 64
 
struct lc_drbg_hash_state {
        struct lc_hash_ctx hash_ctx; /* Cipher handle */
        uint8_t hash_state[LC_SHA512_STATE_SIZE + LC_HASH_COMMON_ALIGNMENT];
        uint8_t V[LC_DRBG_HASH_STATELEN]; /* internal state 10.1.1.1 1a) */
        uint8_t C[LC_DRBG_HASH_STATELEN]; /* static value 10.1.1.1 1b) */
        uint8_t scratchpad[LC_DRBG_HASH_STATELEN + LC_DRBG_HASH_BLOCKLEN];
        /* working mem */
 
        /* Number of RNG requests since last reseed -- 10.1.1.1 1c) */
        size_t reseed_ctr;
        unsigned int seeded : 1;
};
 
#define LC_DRBG_HASH_STATE_SIZE (sizeof(struct lc_drbg_hash_state))
#define LC_DRBG_HASH_CTX_SIZE                                                  \
        ((unsigned long)(LC_DRBG_HASH_STATE_SIZE + sizeof(struct lc_rng)))
 
#define _LC_DRBG_HASH_SET_CTX(name, ctx, offset)                               \
        LC_SHA512_CTX((&(name)->hash_ctx));                                    \
        (name)->reseed_ctr = 0;                                                \
        (name)->seeded = 0
 
#define LC_DRBG_HASH_SET_CTX(name)                                             \
        _LC_DRBG_HASH_SET_CTX(name, name, sizeof(struct lc_drbg_hash_state))
 
extern const struct lc_rng *lc_hash_drbg;
 
#define LC_DRBG_HASH_RNG_CTX(name)                                             \
        LC_RNG_CTX((name), lc_hash_drbg);                                      \
        LC_DRBG_HASH_SET_CTX((struct lc_drbg_hash_state *)name->rng_state);    \
        lc_rng_zero(name)

#define LC_DRBG_HASH_CTX_ON_STACK(name)                                        \
        _Pragma("GCC diagnostic push") _Pragma(                                \
                "GCC diagnostic ignored \"-Wdeclaration-after-statement\"")    \
                LC_ALIGNED_BUFFER(name##_ctx_buf, LC_DRBG_HASH_CTX_SIZE,       \
                                  LC_HASH_COMMON_ALIGNMENT);                   \
        struct lc_rng_ctx *name = (struct lc_rng_ctx *)name##_ctx_buf;         \
        LC_DRBG_HASH_RNG_CTX(name);                                            \
        _Pragma("GCC diagnostic pop")

int lc_drbg_hash_alloc(struct lc_rng_ctx **drbg);

int lc_drbg_hash_healthcheck_sanity(struct lc_rng_ctx *drbg);
 
#ifdef __cplusplus
}
#endif
 
#endif /* LC_HASH_DRBG_H */