lc_kmac.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_KMAC_H
#define LC_KMAC_H
 
#include "lc_hash.h"
#include "lc_rng.h"
#include "lc_sha3.h"
#include "lc_memset_secure.h"
 
#ifdef __cplusplus
extern "C" {
#endif

struct lc_kmac_ctx {
        uint8_t final_called : 1;
        uint8_t rng_initialized : 1;
        uint8_t *shadow_ctx;
        struct lc_hash_ctx hash_ctx;
};
 
#define LC_KMAC_STATE_SIZE(x) (LC_HASH_STATE_SIZE(x))
#define LC_KMAC_STATE_SIZE_REINIT(x) (2 * LC_HASH_STATE_SIZE(x))
#define LC_KMAC_CTX_SIZE(x) (LC_KMAC_STATE_SIZE(x) + sizeof(struct lc_kmac_ctx))
#define LC_KMAC_CTX_SIZE_REINIT(x)                                             \
        (LC_KMAC_STATE_SIZE_REINIT(x) + sizeof(struct lc_kmac_ctx))
 
#define _LC_KMAC_SET_CTX(name, hashname, ctx, offset)                          \
        _LC_HASH_SET_CTX((&name->hash_ctx), hashname, ctx, offset);            \
        name->shadow_ctx = NULL
 
#define LC_KMAC_SET_CTX(name, hashname)                                        \
        _LC_KMAC_SET_CTX(name, hashname, name, sizeof(struct lc_kmac_ctx))
 
#define _LC_KMAC_SET_CTX_REINIT(name, hashname, ctx, offset)                   \
        _LC_HASH_SET_CTX((&name->hash_ctx), hashname, ctx, offset);            \
        name->shadow_ctx = (uint8_t *)((uint8_t *)ctx + offset +               \
                                       LC_HASH_STATE_SIZE(hashname))
 
#define LC_KMAC_SET_CTX_REINIT(name, hashname)                                 \
        _LC_KMAC_SET_CTX_REINIT(name, hashname, name,                          \
                                sizeof(struct lc_kmac_ctx))


int lc_kmac_init(struct lc_kmac_ctx *kmac_ctx, const uint8_t *key, size_t klen,
                 const uint8_t *s, size_t slen);

void lc_kmac_reinit(struct lc_kmac_ctx *kmac_ctx);

void lc_kmac_update(struct lc_kmac_ctx *kmac_ctx, const uint8_t *in,
                    size_t inlen);

void lc_kmac_final(struct lc_kmac_ctx *kmac_ctx, uint8_t *mac, size_t maclen);

void lc_kmac_final_xof(struct lc_kmac_ctx *kmac_ctx, uint8_t *mac,
                       size_t maclen);

int lc_kmac_alloc(const struct lc_hash *hash, struct lc_kmac_ctx **kmac_ctx,
                  uint32_t flags);
 
/*
 * Support re-initialization of state. You set a key during kmac_init,
 * perform a full KMAC operation. After a kmac_final, the re-initialization
 * support allows you to call kmac_reinit and reuse the state for a new
 * operation without providing the keys again. If in doubt, initialize
 * the context with re-init support. The difference is that more memory is
 * allocated to retain the initialized state.
 */
#define LC_KMAC_FLAGS_SUPPORT_REINIT (1 << 0)

void lc_kmac_zero_free(struct lc_kmac_ctx *kmac_ctx);

void lc_kmac_zero(struct lc_kmac_ctx *kmac_ctx);

#define LC_KMAC_CTX_ON_STACK(name, hashname)                                        \
        _Pragma("GCC diagnostic push")                                              \
                _Pragma("GCC diagnostic ignored \"-Wvla\"") _Pragma(                \
                        "GCC diagnostic ignored \"-Wdeclaration-after-statement\"") \
                        LC_ALIGNED_BUFFER(name##_ctx_buf,                           \
                                          LC_KMAC_CTX_SIZE(hashname),               \
                                          LC_HASH_COMMON_ALIGNMENT);                \
        struct lc_kmac_ctx *name = (struct lc_kmac_ctx *)name##_ctx_buf;            \
        LC_KMAC_SET_CTX(name, hashname);                                            \
        lc_kmac_zero(name);                                                         \
        _Pragma("GCC diagnostic pop")

#define LC_KMAC_CTX_ON_STACK_REINIT(name, hashname)                                 \
        _Pragma("GCC diagnostic push")                                              \
                _Pragma("GCC diagnostic ignored \"-Wvla\"") _Pragma(                \
                        "GCC diagnostic ignored \"-Wdeclaration-after-statement\"") \
                        LC_ALIGNED_BUFFER(name##_ctx_buf,                           \
                                          LC_KMAC_CTX_SIZE_REINIT(hashname),        \
                                          LC_HASH_COMMON_ALIGNMENT);                \
        struct lc_kmac_ctx *name = (struct lc_kmac_ctx *)name##_ctx_buf;            \
        LC_KMAC_SET_CTX_REINIT(name, hashname);                                     \
        lc_kmac_zero(name);                                                         \
        _Pragma("GCC diagnostic pop")

size_t lc_kmac_macsize(struct lc_kmac_ctx *kmac_ctx);

int lc_kmac(const struct lc_hash *hash, const uint8_t *key, size_t keylen,
            const uint8_t *s, size_t slen, const uint8_t *in, size_t inlen,
            uint8_t *mac, size_t maclen);

int lc_kmac_xof(const struct lc_hash *hash, const uint8_t *key, size_t keylen,
                const uint8_t *s, size_t slen, const uint8_t *in, size_t inlen,
                uint8_t *mac, size_t maclen);
 
/******************************** KMAC as RNG *********************************/

 
/* KMAC DRNG implementation */
extern const struct lc_rng *lc_kmac_rng;

#define LC_KMAC_KDF_DRNG_CTX_SIZE(hashname)                                    \
        (sizeof(struct lc_rng_ctx) + LC_KMAC_CTX_SIZE(hashname))
 
#define LC_KMAC_KDF_DRNG_SET_CTX(name, hashname) LC_KMAC_SET_CTX(name, hashname)
 
#define LC_KMAC_KDF_RNG_CTX(name, hashname)                                    \
        LC_RNG_CTX(name, lc_kmac_rng);                                         \
        LC_KMAC_KDF_DRNG_SET_CTX(((struct lc_kmac_ctx *)(name->rng_state)),    \
                                 hashname);                                    \
        lc_rng_zero(name)

#define LC_KMAC_KDF_DRNG_CTX_ON_STACK(name, hashname)                               \
        _Pragma("GCC diagnostic push")                                              \
                _Pragma("GCC diagnostic ignored \"-Wvla\"") _Pragma(                \
                        "GCC diagnostic ignored \"-Wdeclaration-after-statement\"") \
                        LC_ALIGNED_BUFFER(name##_ctx_buf,                           \
                                          LC_KMAC_KDF_DRNG_CTX_SIZE(hashname),      \
                                          LC_HASH_COMMON_ALIGNMENT);                \
        struct lc_rng_ctx *name = (struct lc_rng_ctx *)name##_ctx_buf;              \
        LC_KMAC_KDF_RNG_CTX(name, hashname);                                        \
        _Pragma("GCC diagnostic pop")

int lc_kmac_rng_alloc(struct lc_rng_ctx **state, const struct lc_hash *hash);
 
#ifdef __cplusplus
}
#endif
 
#endif /* LC_KMAC_H */