root
/
openssl
mirror of https://github.com/openssl/openssl.git
1
0
Fork 0
Code Issues Actions 7 Packages Projects Releases Wiki Activity
openssl/crypto/slh_dsa/slh_wots.c

316 lines
11 KiB
C
Raw Permalink Blame History

/*
* Copyright 2024-2025 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
*/
#include <string.h>
#include <openssl/crypto.h>
#include "slh_dsa_local.h"
#include "slh_dsa_key.h"
/* For the parameter sets defined there is only one w value */
#define SLH_WOTS_LOGW 4
#define SLH_WOTS_W 16
#define SLH_WOTS_LEN1(n) (2 * (n))
#define SLH_WOTS_LEN2 3
#define SLH_WOTS_CHECKSUM_LEN ((SLH_WOTS_LEN2 + SLH_WOTS_LOGW + 7) / 8)
#define SLH_WOTS_LEN_MAX SLH_WOTS_LEN(SLH_MAX_N)
#define NIBBLE_MASK 15
#define NIBBLE_SHIFT 4
/*
* @brief Convert a byte array to a byte array of (4 bit) nibbles
* This is a Variant of the FIPS 205 Algorithm 4 base_2^b function.
*
* @param in A byte message to convert
* @param in_len The size of |in|.
* @param out The returned array of nibbles, with a size of 2*|in_len|
*/
static ossl_inline void slh_bytes_to_nibbles(const uint8_t *in, size_t in_len,
uint8_t *out)
{
size_t consumed = 0;
for (consumed = 0; consumed < in_len; consumed++) {
*out++ = (*in >> NIBBLE_SHIFT);
*out++ = (*in++ & NIBBLE_MASK);
}
}
/*
* With w = 16 the maximum checksum is 0xF * n which fits into 12 bits
* which is 3 nibbles.
*
* This is effectively a cutdown version of Algorithm 7: steps 3 to 6
* which does a complicated base2^b(tobyte()) operation.
*/
static ossl_inline void compute_checksum_nibbles(const uint8_t *in, size_t in_len,
uint8_t *out)
{
size_t i;
uint16_t csum = 0;
/* Compute checksum */
for (i = 0; i < in_len; ++i)
csum += in[i];
/*
* This line is effectively the same as doing csum += NIBBLE_MASK - in[i]
* in the loop above.
*/
csum = (uint16_t)(NIBBLE_MASK * in_len) - csum;
/* output checksum as 3 nibbles */
out[0] = (csum >> (2 * NIBBLE_SHIFT)) & NIBBLE_MASK;
out[1] = (csum >> NIBBLE_SHIFT) & NIBBLE_MASK;
out[2] = csum & NIBBLE_MASK;
}
/**
* @brief WOTS+ Chaining function
* See FIPS 205 Section 5 Algorithm 5
*
* Iterates using a hash function on the input |steps| times starting at index
* |start|. (Internally the |adrs| hash address is used to update the chaining
* index).
*
* @param ctx Contains SLH_DSA algorithm functions and constants.
* @param in An input string of |n| bytes
* @param start_index The chaining start index
* @param steps The number of iterations starting from |start_index|
* Note |start_index| + |steps| < w
* (where w = 16 indicates the length of the hash chains)
* @param pk_seed A public key seed (which is added to the hash)
* @param adrs An ADRS object which has a type of WOTS_HASH, and has a layer
* address, tree address, key pair address and chain address
* @params wpkt A WPACKET object to write the hash chain to (n bytes are written)
* @returns 1 on success, or 0 on error.
*/
static int slh_wots_chain(SLH_DSA_HASH_CTX *ctx, const uint8_t *in,
uint8_t start_index, uint8_t steps,
const uint8_t *pk_seed, uint8_t *adrs, WPACKET *wpkt)
{
const SLH_DSA_KEY *key = ctx->key;
SLH_HASH_FUNC_DECLARE(key, hashf);
SLH_ADRS_FUNC_DECLARE(key, adrsf);
SLH_HASH_FN_DECLARE(hashf, F);
SLH_ADRS_FN_DECLARE(adrsf, set_hash_address);
size_t j = start_index, end_index;
size_t n = key->params->n;
uint8_t *tmp; /* Pointer into the |wpkt| buffer */
size_t tmp_len = n;
if (steps == 0)
return WPACKET_memcpy(wpkt, in, n);
if (!WPACKET_allocate_bytes(wpkt, tmp_len, &tmp))
return 0;
set_hash_address(adrs, (uint32_t)(j++));
if (!F(ctx, pk_seed, adrs, in, n, tmp, tmp_len))
return 0;
end_index = start_index + steps;
for (; j < end_index; ++j) {
set_hash_address(adrs, (uint32_t)j);
if (!F(ctx, pk_seed, adrs, tmp, n, tmp, tmp_len))
return 0;
}
return 1;
}
/**
* @brief WOTS+ Public key generation.
* See FIPS 205 Section 5.1 Algorithm 6
*
* @param ctx Contains SLH_DSA algorithm functions and constants.
* @param sk_seed A private key seed of size |n|
* @param pk_seed A public key seed of size |n|
* @param adrs An ADRS object containing the layer address, tree address and
* keypair address of the WOTS+ public key to generate.
* @param pk_out The generated public key of size |n|
* @param pk_out_len The maximum size of |pk_out|
* @returns 1 on success, or 0 on error.
*/
int ossl_slh_wots_pk_gen(SLH_DSA_HASH_CTX *ctx,
const uint8_t *sk_seed, const uint8_t *pk_seed,
uint8_t *adrs, uint8_t *pk_out, size_t pk_out_len)
{
int ret = 0;
const SLH_DSA_KEY *key = ctx->key;
size_t n = key->params->n;
size_t i, len = SLH_WOTS_LEN(n); /* 2 * n + 3 */
uint8_t sk[SLH_MAX_N];
uint8_t tmp[SLH_WOTS_LEN_MAX * SLH_MAX_N];
WPACKET pkt, *tmp_wpkt = &pkt; /* Points to the |tmp| buffer */
size_t tmp_len = 0;
SLH_HASH_FUNC_DECLARE(key, hashf);
SLH_ADRS_FUNC_DECLARE(key, adrsf);
SLH_HASH_FN_DECLARE(hashf, PRF);
SLH_ADRS_FN_DECLARE(adrsf, set_chain_address);
SLH_ADRS_DECLARE(sk_adrs);
SLH_ADRS_DECLARE(wots_pk_adrs);
if (!WPACKET_init_static_len(tmp_wpkt, tmp, sizeof(tmp), 0))
return 0;
adrsf->copy(sk_adrs, adrs);
adrsf->set_type_and_clear(sk_adrs, SLH_ADRS_TYPE_WOTS_PRF);
adrsf->copy_keypair_address(sk_adrs, adrs);
for (i = 0; i < len; ++i) { /* len = 2n + 3 */
set_chain_address(sk_adrs, (uint32_t)i);
if (!PRF(ctx, pk_seed, sk_seed, sk_adrs, sk, sizeof(sk)))
goto end;
set_chain_address(adrs, (uint32_t)i);
if (!slh_wots_chain(ctx, sk, 0, NIBBLE_MASK, pk_seed, adrs, tmp_wpkt))
goto end;
}
if (!WPACKET_get_total_written(tmp_wpkt, &tmp_len)) /* should be n * (2 * n + 3) */
goto end;
adrsf->copy(wots_pk_adrs, adrs);
adrsf->set_type_and_clear(wots_pk_adrs, SLH_ADRS_TYPE_WOTS_PK);
adrsf->copy_keypair_address(wots_pk_adrs, adrs);
ret = hashf->T(ctx, pk_seed, wots_pk_adrs, tmp, tmp_len, pk_out, pk_out_len);
end:
WPACKET_finish(tmp_wpkt);
OPENSSL_cleanse(tmp, sizeof(tmp));
OPENSSL_cleanse(sk, n);
return ret;
}
/**
* @brief WOTS+ Signature generation
* See FIPS 205 Section 5.2 Algorithm 7
*
* The returned signature size is len * |n| bytes (where len = 2 * |n| + 3).
*
* @param ctx Contains SLH_DSA algorithm functions and constants.
* @param msg An input message of size |n| bytes.
* The message is either an XMSS or FORS public key
* @param sk_seed The private key seed of size |n| bytes
* @param pk_seed The public key seed of size |n| bytes
* @param adrs An address containing the layer address, tree address and key
* pair address. The size is either 32 or 22 bytes.
* @param sig_wpkt A WPACKET object to write the signature to.
* @returns 1 on success, or 0 on error.
*/
int ossl_slh_wots_sign(SLH_DSA_HASH_CTX *ctx, const uint8_t *msg,
const uint8_t *sk_seed, const uint8_t *pk_seed,
uint8_t *adrs, WPACKET *sig_wpkt)
{
int ret = 0;
const SLH_DSA_KEY *key = ctx->key;
uint8_t msg_and_csum_nibbles[SLH_WOTS_LEN_MAX]; /* size is >= 2 * n + 3 */
uint8_t sk[SLH_MAX_N];
size_t i;
size_t n = key->params->n;
size_t len1 = SLH_WOTS_LEN1(n); /* 2 * n = the msg length in nibbles */
size_t len = len1 + SLH_WOTS_LEN2; /* 2 * n + 3 (3 checksum nibbles) */
SLH_ADRS_DECLARE(sk_adrs);
SLH_HASH_FUNC_DECLARE(key, hashf);
SLH_ADRS_FUNC_DECLARE(key, adrsf);
SLH_HASH_FN_DECLARE(hashf, PRF);
SLH_ADRS_FN_DECLARE(adrsf, set_chain_address);
/*
* Convert n message bytes to 2*n base w=16 integers
* i.e. Convert message to an array of 2*n nibbles.
*/
slh_bytes_to_nibbles(msg, n, msg_and_csum_nibbles);
/* Compute a 12 bit checksum and add it to the end */
compute_checksum_nibbles(msg_and_csum_nibbles, len1, msg_and_csum_nibbles + len1);
adrsf->copy(sk_adrs, adrs);
adrsf->set_type_and_clear(sk_adrs, SLH_ADRS_TYPE_WOTS_PRF);
adrsf->copy_keypair_address(sk_adrs, adrs);
for (i = 0; i < len; ++i) {
set_chain_address(sk_adrs, (uint32_t)i);
/* compute chain i secret */
if (!PRF(ctx, pk_seed, sk_seed, sk_adrs, sk, sizeof(sk)))
goto err;
set_chain_address(adrs, (uint32_t)i);
/* compute chain i signature */
if (!slh_wots_chain(ctx, sk, 0, msg_and_csum_nibbles[i],
pk_seed, adrs, sig_wpkt))
goto err;
}
ret = 1;
err:
return ret;
}
/**
* @brief Compute a candidate WOTS+ public key from a message and signature
* See FIPS 205 Section 5.3 Algorithm 8
*
* The size of the signature is len * |n| bytes (where len = 2 * |n| + 3).
*
* @param ctx Contains SLH_DSA algorithm functions and constants.
* @param sig_rpkt A PACKET object to read a WOTS+ signature from
* @param msg A message of size |n| bytes.
* @param pk_seed The public key seed of size |n|.
* @param adrs An ADRS object containing the layer address, tree address and
* key pair address that of the WOTS+ key used to sign the message.
* @param pk_out The returned public key candidate of size |n|
* @param pk_out_len The maximum size of |pk_out|
* @returns 1 on success, or 0 on error.
*/
int ossl_slh_wots_pk_from_sig(SLH_DSA_HASH_CTX *ctx,
PACKET *sig_rpkt, const uint8_t *msg,
const uint8_t *pk_seed, uint8_t *adrs,
uint8_t *pk_out, size_t pk_out_len)
{
int ret = 0;
const SLH_DSA_KEY *key = ctx->key;
uint8_t msg_and_csum_nibbles[SLH_WOTS_LEN_MAX];
size_t i;
size_t n = key->params->n;
size_t len1 = SLH_WOTS_LEN1(n);
size_t len = len1 + SLH_WOTS_LEN2; /* 2n + 3 */
const uint8_t *sig_i; /* Pointer into |sig_rpkt| buffer */
uint8_t tmp[SLH_WOTS_LEN_MAX * SLH_MAX_N];
WPACKET pkt, *tmp_pkt = &pkt;
size_t tmp_len = 0;
SLH_HASH_FUNC_DECLARE(key, hashf);
SLH_ADRS_FUNC_DECLARE(key, adrsf);
SLH_ADRS_FN_DECLARE(adrsf, set_chain_address);
SLH_ADRS_DECLARE(wots_pk_adrs);
if (!WPACKET_init_static_len(tmp_pkt, tmp, sizeof(tmp), 0))
return 0;
slh_bytes_to_nibbles(msg, n, msg_and_csum_nibbles);
compute_checksum_nibbles(msg_and_csum_nibbles, len1, msg_and_csum_nibbles + len1);
/* Compute the end nodes for each of the chains */
for (i = 0; i < len; ++i) {
set_chain_address(adrs, (uint32_t)i);
if (!PACKET_get_bytes(sig_rpkt, &sig_i, n)
|| !slh_wots_chain(ctx, sig_i, msg_and_csum_nibbles[i],
NIBBLE_MASK - msg_and_csum_nibbles[i],
pk_seed, adrs, tmp_pkt))
goto err;
}
/* compress the computed public key value */
adrsf->copy(wots_pk_adrs, adrs);
adrsf->set_type_and_clear(wots_pk_adrs, SLH_ADRS_TYPE_WOTS_PK);
adrsf->copy_keypair_address(wots_pk_adrs, adrs);
if (!WPACKET_get_total_written(tmp_pkt, &tmp_len))
goto err;
ret = hashf->T(ctx, pk_seed, wots_pk_adrs, tmp, tmp_len,
pk_out, pk_out_len);
err:
if (!WPACKET_finish(tmp_pkt))
ret = 0;
return ret;
}
Reference in New Issue View Git Blame Copy Permalink