openssl/include/crypto/lms_util.h

55 lines
1.8 KiB
C

/*
* Copyright 2025 The OpenSSL Project Authors. All Rights Reserved.
*
* Licensed under the Apache License 2.0 (the "License"). You may not use
* this file except in compliance with the License. You can obtain a copy
* in the file LICENSE in the source distribution or at
* https://www.openssl.org/source/license.html
*/
/* @brief Internal LMS helper functions */
#include "internal/packet.h"
#include <openssl/params.h>
#include <openssl/core_names.h>
#include <openssl/evp.h>
/*
* This LMS implementation assumes that the hash algorithm must be the same for
* LMS params and OTS params. Since OpenSSL does not have a "SHAKE256-192"
* algorithm, we have to check the digest size as well as the name.
* This macro can be used to compare 2 LMS_PARAMS, LMS_PARAMS and LM_OTS_PARAMS.
*/
#define HASH_NOT_MATCHED(a, b) \
(a)->n != (b)->n || (strcmp((a)->digestname, (b)->digestname) != 0)
/*
* See RFC 8554 Section 3.1.3: Strings of w-bit Elements
* w: Is one of {1,2,4,8}
*/
static ossl_unused ossl_inline
uint8_t lms_ots_coef(const unsigned char *S, uint16_t i, uint8_t w)
{
uint8_t bitmask = (1 << w) - 1;
uint8_t shift = 8 - (w * (i % (8 / w)) + w);
int id = (i * w) / 8;
return (S[id] >> shift) & bitmask;
}
static ossl_unused ossl_inline
int lms_evp_md_ctx_init(EVP_MD_CTX *ctx, const EVP_MD *md,
const LMS_PARAMS *lms_params)
{
OSSL_PARAM params[2] = { OSSL_PARAM_END, OSSL_PARAM_END };
OSSL_PARAM *p = NULL;
/* The OpenSSL SHAKE implementation requires the xoflen to be set */
if (strncmp(lms_params->digestname, "SHAKE", 5) == 0) {
params[0] = OSSL_PARAM_construct_uint32(OSSL_DIGEST_PARAM_XOFLEN,
(uint32_t *)&lms_params->n);
p = params;
}
return EVP_DigestInit_ex2(ctx, md, p);
}