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pqcrypto/crypto_sign/mqdss-48/clean/sign.c
2019-04-30 10:29:48 +02:00

386 lines
14 KiB
C

#include <assert.h>
#include <stdint.h>
#include <stddef.h>
#include <string.h>
#include "api.h"
#include "fips202.h"
#include "gf31.h"
#include "mq.h"
#include "params.h"
#include "randombytes.h"
/* Takes an array of len bytes and computes a hash digest.
This is used as a hash function in the Fiat-Shamir transform. */
static void H(unsigned char *out, const unsigned char *in, const size_t len)
{
shake256(out, HASH_BYTES, in, len);
}
/* Takes two arrays of N packed elements and an array of M packed elements,
and computes a HASH_BYTES commitment. */
static void com_0(unsigned char *c,
const unsigned char *rho,
const unsigned char *inn, const unsigned char *inn2,
const unsigned char *inm)
{
unsigned char buffer[HASH_BYTES + 2*NPACKED_BYTES + MPACKED_BYTES];
memcpy(buffer, rho, HASH_BYTES);
memcpy(buffer + HASH_BYTES, inn, NPACKED_BYTES);
memcpy(buffer + HASH_BYTES + NPACKED_BYTES, inn2, NPACKED_BYTES);
memcpy(buffer + HASH_BYTES + 2*NPACKED_BYTES, inm, MPACKED_BYTES);
shake256(c, HASH_BYTES, buffer, HASH_BYTES + 2*NPACKED_BYTES + MPACKED_BYTES);
}
/* Takes an array of N packed elements and an array of M packed elements,
and computes a HASH_BYTES commitment. */
static void com_1(unsigned char *c,
const unsigned char *rho,
const unsigned char *inn, const unsigned char *inm)
{
unsigned char buffer[HASH_BYTES + NPACKED_BYTES + MPACKED_BYTES];
memcpy(buffer, rho, HASH_BYTES);
memcpy(buffer + HASH_BYTES, inn, NPACKED_BYTES);
memcpy(buffer + HASH_BYTES + NPACKED_BYTES, inm, MPACKED_BYTES);
shake256(c, HASH_BYTES, buffer, HASH_BYTES + NPACKED_BYTES + MPACKED_BYTES);
}
/*
* Generates an MQDSS key pair.
*/
int PQCLEAN_MQDSS48_CLEAN_crypto_sign_keypair(uint8_t *pk, uint8_t *sk) {
signed char F[F_LEN];
unsigned char skbuf[SEED_BYTES * 2];
gf31 sk_gf31[N];
gf31 pk_gf31[M];
// Expand sk to obtain a seed for F and the secret input s.
// We also expand to obtain a value for sampling r0, t0 and e0 during
// signature generation, but that is not relevant here.
randombytes(sk, SEED_BYTES);
shake256(skbuf, SEED_BYTES * 2, sk, SEED_BYTES);
memcpy(pk, skbuf, SEED_BYTES);
PQCLEAN_MQDSS48_CLEAN_gf31_nrand_schar(F, F_LEN, pk, SEED_BYTES);
PQCLEAN_MQDSS48_CLEAN_gf31_nrand(sk_gf31, N, skbuf + SEED_BYTES, SEED_BYTES);
PQCLEAN_MQDSS48_CLEAN_MQ(pk_gf31, sk_gf31, F);
PQCLEAN_MQDSS48_CLEAN_vgf31_unique(pk_gf31, pk_gf31);
PQCLEAN_MQDSS48_CLEAN_gf31_npack(pk + SEED_BYTES, pk_gf31, M);
return 0;
}
/**
* Returns an array containing a detached signature.
*/
int PQCLEAN_MQDSS48_CLEAN_crypto_sign_signature(
uint8_t *sig, size_t *siglen,
const uint8_t *m, size_t mlen, const uint8_t *sk) {
(void)sig;
(void)siglen;
(void)m;
(void)mlen;
(void)sk;
return 0;
}
/**
* Verifies a detached signature and message under a given public key.
*/
int PQCLEAN_MQDSS48_CLEAN_crypto_sign_verify(
const uint8_t *sig, size_t siglen,
const uint8_t *m, size_t mlen, const uint8_t *pk) {
(void)sig;
(void)siglen;
(void)m;
(void)mlen;
(void)pk;
return 0;
}
/**
* Returns an array containing the signature followed by the message.
*/
int PQCLEAN_MQDSS48_CLEAN_crypto_sign(
uint8_t *sm, size_t *smlen,
const uint8_t *m, size_t mlen, const uint8_t *sk) {
signed char F[F_LEN];
unsigned char skbuf[SEED_BYTES * 4];
gf31 pk_gf31[M];
unsigned char pk[SEED_BYTES + MPACKED_BYTES];
// Concatenated for convenient hashing.
unsigned char D_sigma0_h0_sigma1[HASH_BYTES * 3 + ROUNDS * (NPACKED_BYTES + MPACKED_BYTES)];
unsigned char *D = D_sigma0_h0_sigma1;
unsigned char *sigma0 = D_sigma0_h0_sigma1 + HASH_BYTES;
unsigned char *h0 = D_sigma0_h0_sigma1 + 2*HASH_BYTES;
unsigned char *t1packed = D_sigma0_h0_sigma1 + 3*HASH_BYTES;
unsigned char *e1packed = D_sigma0_h0_sigma1 + 3*HASH_BYTES + ROUNDS * NPACKED_BYTES;
uint64_t shakestate[25] = {0};
unsigned char shakeblock[SHAKE256_RATE];
unsigned char h1[((ROUNDS + 7) & ~7) >> 3];
unsigned char rnd_seed[HASH_BYTES + SEED_BYTES];
unsigned char rho[2 * ROUNDS * HASH_BYTES];
unsigned char *rho0 = rho;
unsigned char *rho1 = rho + ROUNDS * HASH_BYTES;
gf31 sk_gf31[N];
gf31 rnd[(2 * N + M) * ROUNDS]; // Concatenated for easy RNG.
gf31 *r0 = rnd;
gf31 *t0 = rnd + N * ROUNDS;
gf31 *e0 = rnd + 2 * N * ROUNDS;
gf31 r1[N * ROUNDS];
gf31 t1[N * ROUNDS];
gf31 e1[M * ROUNDS];
gf31 gx[M * ROUNDS];
unsigned char packbuf0[NPACKED_BYTES];
unsigned char packbuf1[NPACKED_BYTES];
unsigned char packbuf2[MPACKED_BYTES];
unsigned char c[HASH_BYTES * ROUNDS * 2];
gf31 alpha;
int alpha_count = 0;
unsigned char b;
int i, j;
shake256(skbuf, SEED_BYTES * 4, sk, SEED_BYTES);
PQCLEAN_MQDSS48_CLEAN_gf31_nrand_schar(F, F_LEN, skbuf, SEED_BYTES);
assert(SIG_LEN > SEED_BYTES);
memcpy(sm + SIG_LEN - SEED_BYTES, sk, SEED_BYTES);
memcpy(sm + SIG_LEN, m, mlen);
H(sm, sm + SIG_LEN - SEED_BYTES, mlen + SEED_BYTES); // Compute R.
memcpy(pk, skbuf, SEED_BYTES);
PQCLEAN_MQDSS48_CLEAN_gf31_nrand(sk_gf31, N, skbuf + SEED_BYTES, SEED_BYTES);
PQCLEAN_MQDSS48_CLEAN_MQ(pk_gf31, sk_gf31, F);
PQCLEAN_MQDSS48_CLEAN_vgf31_unique(pk_gf31, pk_gf31);
PQCLEAN_MQDSS48_CLEAN_gf31_npack(pk + SEED_BYTES, pk_gf31, M);
memcpy(sm + SIG_LEN - HASH_BYTES - PK_BYTES, pk, PK_BYTES);
memcpy(sm + SIG_LEN - HASH_BYTES, sm, HASH_BYTES);
H(D, sm + SIG_LEN - HASH_BYTES - PK_BYTES, mlen + PK_BYTES + HASH_BYTES);
sm += HASH_BYTES; // Compensate for prefixed R.
memcpy(rnd_seed, skbuf + 2*SEED_BYTES, SEED_BYTES);
memcpy(rnd_seed + SEED_BYTES, D, HASH_BYTES);
shake256(rho, 2 * ROUNDS * HASH_BYTES, rnd_seed, SEED_BYTES + HASH_BYTES);
memcpy(rnd_seed, skbuf + 3*SEED_BYTES, SEED_BYTES);
memcpy(rnd_seed + SEED_BYTES, D, HASH_BYTES);
PQCLEAN_MQDSS48_CLEAN_gf31_nrand(rnd, (2 * N + M) * ROUNDS, rnd_seed, SEED_BYTES + HASH_BYTES);
for (i = 0; i < ROUNDS; i++) {
for (j = 0; j < N; j++) {
r1[j + i*N] = (gf31)(31 + sk_gf31[j] - r0[j + i*N]);
}
PQCLEAN_MQDSS48_CLEAN_G(gx + i*M, t0 + i*N, r1 + i*N, F);
}
for (i = 0; i < ROUNDS * M; i++) {
gx[i] = (gf31)(gx[i] + e0[i]);
}
for (i = 0; i < ROUNDS; i++) {
PQCLEAN_MQDSS48_CLEAN_gf31_npack(packbuf0, r0 + i*N, N);
PQCLEAN_MQDSS48_CLEAN_gf31_npack(packbuf1, t0 + i*N, N);
PQCLEAN_MQDSS48_CLEAN_gf31_npack(packbuf2, e0 + i*M, M);
com_0(c + HASH_BYTES * (2*i + 0), rho0 + i*HASH_BYTES, packbuf0, packbuf1, packbuf2);
PQCLEAN_MQDSS48_CLEAN_vgf31_shorten_unique(r1 + i*N, r1 + i*N);
PQCLEAN_MQDSS48_CLEAN_vgf31_shorten_unique(gx + i*M, gx + i*M);
PQCLEAN_MQDSS48_CLEAN_gf31_npack(packbuf0, r1 + i*N, N);
PQCLEAN_MQDSS48_CLEAN_gf31_npack(packbuf1, gx + i*M, M);
com_1(c + HASH_BYTES * (2*i + 1), rho1 + i*HASH_BYTES, packbuf0, packbuf1);
}
H(sigma0, c, HASH_BYTES * ROUNDS * 2); // Compute sigma_0.
shake256_absorb(shakestate, D_sigma0_h0_sigma1, 2 * HASH_BYTES);
shake256_squeezeblocks(shakeblock, 1, shakestate);
memcpy(h0, shakeblock, HASH_BYTES);
memcpy(sm, sigma0, HASH_BYTES);
sm += HASH_BYTES; // Compensate for sigma_0.
for (i = 0; i < ROUNDS; i++) {
do {
alpha = shakeblock[alpha_count] & 31;
alpha_count++;
if (alpha_count == SHAKE256_RATE) {
alpha_count = 0;
shake256_squeezeblocks(shakeblock, 1, shakestate);
}
} while (alpha == 31);
for (j = 0; j < N; j++) {
t1[i*N + j] = (gf31)(alpha * r0[j + i*N] - t0[j + i*N] + 31);
}
PQCLEAN_MQDSS48_CLEAN_MQ(e1 + i*M, r0 + i*N, F);
for (j = 0; j < N; j++) {
e1[i*N + j] = (gf31)(alpha * e1[j + i*M] - e0[j + i*M] + 31);
}
PQCLEAN_MQDSS48_CLEAN_vgf31_shorten_unique(t1 + i*N, t1 + i*N);
PQCLEAN_MQDSS48_CLEAN_vgf31_shorten_unique(e1 + i*N, e1 + i*N);
}
PQCLEAN_MQDSS48_CLEAN_gf31_npack(t1packed, t1, N * ROUNDS);
PQCLEAN_MQDSS48_CLEAN_gf31_npack(e1packed, e1, M * ROUNDS);
memcpy(sm, t1packed, NPACKED_BYTES * ROUNDS);
sm += NPACKED_BYTES * ROUNDS;
memcpy(sm, e1packed, MPACKED_BYTES * ROUNDS);
sm += MPACKED_BYTES * ROUNDS;
shake256(h1, ((ROUNDS + 7) & ~7) >> 3, D_sigma0_h0_sigma1, 3*HASH_BYTES + ROUNDS*(NPACKED_BYTES + MPACKED_BYTES));
for (i = 0; i < ROUNDS; i++) {
b = (h1[(i >> 3)] >> (i & 7)) & 1;
if (b == 0) {
PQCLEAN_MQDSS48_CLEAN_gf31_npack(sm, r0+i*N, N);
} else if (b == 1) {
PQCLEAN_MQDSS48_CLEAN_gf31_npack(sm, r1+i*N, N);
}
memcpy(sm + NPACKED_BYTES, c + HASH_BYTES * (2*i + (1 - b)), HASH_BYTES);
memcpy(sm + NPACKED_BYTES + HASH_BYTES, rho + (i + b * ROUNDS) * HASH_BYTES, HASH_BYTES);
sm += NPACKED_BYTES + 2*HASH_BYTES;
}
*smlen = SIG_LEN + mlen;
return 0;
}
/**
* Verifies a given signature-message pair under a given public key.
*/
int PQCLEAN_MQDSS48_CLEAN_crypto_sign_open(
uint8_t *m, size_t *mlen,
const uint8_t *sm, size_t smlen, const uint8_t *pk)
{
gf31 r[N];
gf31 t[N];
gf31 e[M];
signed char F[F_LEN];
gf31 pk_gf31[M];
unsigned char sig[SIG_LEN];
unsigned char *sigptr = sig;
// Concatenated for convenient hashing.
unsigned char D_sigma0_h0_sigma1[HASH_BYTES * 3 + ROUNDS * (NPACKED_BYTES + MPACKED_BYTES)];
unsigned char *D = D_sigma0_h0_sigma1;
unsigned char *sigma0 = D_sigma0_h0_sigma1 + HASH_BYTES;
unsigned char *h0 = D_sigma0_h0_sigma1 + 2*HASH_BYTES;
unsigned char *t1packed = D_sigma0_h0_sigma1 + 3*HASH_BYTES;
unsigned char *e1packed = D_sigma0_h0_sigma1 + 3*HASH_BYTES + ROUNDS * NPACKED_BYTES;
unsigned char h1[((ROUNDS + 7) & ~7) >> 3];
unsigned char c[HASH_BYTES * ROUNDS * 2];
memset(c, 0, HASH_BYTES*2);
gf31 x[N];
gf31 y[M];
gf31 z[M];
unsigned char packbuf0[NPACKED_BYTES];
unsigned char packbuf1[MPACKED_BYTES];
uint64_t shakestate[25] = {0};
unsigned char shakeblock[SHAKE256_RATE];
int i, j;
gf31 alpha;
int alpha_count = 0;
unsigned char b;
/* The API caller does not necessarily know what size a signature should be
but MQDSS signatures are always exactly SIG_LEN. */
if (smlen < SIG_LEN) {
memset(m, 0, smlen);
*mlen = 0;
return 1;
}
*mlen = smlen - SIG_LEN;
/* Create a copy of the signature so that m = sm is not an issue */
memcpy(sig, sm, SIG_LEN);
/* Put the message all the way at the end of the m buffer, so that we can
* prepend the required other inputs for the hash function. */
memcpy(m + SIG_LEN, sm + SIG_LEN, *mlen);
memcpy(m + SIG_LEN - PK_BYTES - HASH_BYTES, pk, PK_BYTES); // Copy pk to m.
memcpy(m + SIG_LEN - HASH_BYTES, sigptr, HASH_BYTES); // Copy R to m.
H(D, m + SIG_LEN - PK_BYTES - HASH_BYTES, *mlen + PK_BYTES + HASH_BYTES);
sigptr += HASH_BYTES;
PQCLEAN_MQDSS48_CLEAN_gf31_nrand_schar(F, F_LEN, pk, SEED_BYTES);
pk += SEED_BYTES;
PQCLEAN_MQDSS48_CLEAN_gf31_nunpack(pk_gf31, pk, M);
memcpy(sigma0, sigptr, HASH_BYTES);
shake256_absorb(shakestate, D_sigma0_h0_sigma1, 2 * HASH_BYTES);
shake256_squeezeblocks(shakeblock, 1, shakestate);
memcpy(h0, shakeblock, HASH_BYTES);
sigptr += HASH_BYTES;
memcpy(t1packed, sigptr, ROUNDS * NPACKED_BYTES);
sigptr += ROUNDS*NPACKED_BYTES;
memcpy(e1packed, sigptr, ROUNDS * MPACKED_BYTES);
sigptr += ROUNDS*MPACKED_BYTES;
shake256(h1, ((ROUNDS + 7) & ~7) >> 3, D_sigma0_h0_sigma1, 3*HASH_BYTES + ROUNDS*(NPACKED_BYTES + MPACKED_BYTES));
for (i = 0; i < ROUNDS; i++) {
do {
alpha = shakeblock[alpha_count] & 31;
alpha_count++;
if (alpha_count == SHAKE256_RATE) {
alpha_count = 0;
shake256_squeezeblocks(shakeblock, 1, shakestate);
}
} while (alpha == 31);
b = (h1[(i >> 3)] >> (i & 7)) & 1;
PQCLEAN_MQDSS48_CLEAN_gf31_nunpack(r, sigptr, N);
PQCLEAN_MQDSS48_CLEAN_gf31_nunpack(t, t1packed + NPACKED_BYTES*i, N);
PQCLEAN_MQDSS48_CLEAN_gf31_nunpack(e, e1packed + MPACKED_BYTES*i, M);
if (b == 0) {
PQCLEAN_MQDSS48_CLEAN_MQ(y, r, F);
for (j = 0; j < N; j++) {
x[j] = (gf31)(alpha * r[j] - t[j] + 31);
}
for (j = 0; j < N; j++) {
y[j] = (gf31)(alpha * y[j] - e[j] + 31);
}
PQCLEAN_MQDSS48_CLEAN_vgf31_shorten_unique(x, x);
PQCLEAN_MQDSS48_CLEAN_vgf31_shorten_unique(y, y);
PQCLEAN_MQDSS48_CLEAN_gf31_npack(packbuf0, x, N);
PQCLEAN_MQDSS48_CLEAN_gf31_npack(packbuf1, y, M);
com_0(c + HASH_BYTES*(2*i + 0), sigptr + HASH_BYTES + NPACKED_BYTES, sigptr, packbuf0, packbuf1);
} else {
PQCLEAN_MQDSS48_CLEAN_MQ(y, r, F);
PQCLEAN_MQDSS48_CLEAN_G(z, t, r, F);
for (j = 0; j < N; j++) {
y[j] = (gf31)(alpha * (31 + pk_gf31[j] - y[j]) - z[j] - e[j] + 62);
}
PQCLEAN_MQDSS48_CLEAN_vgf31_shorten_unique(y, y);
PQCLEAN_MQDSS48_CLEAN_gf31_npack(packbuf0, y, M);
com_1(c + HASH_BYTES*(2*i + 1), sigptr + HASH_BYTES + NPACKED_BYTES, sigptr, packbuf0);
}
memcpy(c + HASH_BYTES*(2*i + (1 - b)), sigptr + NPACKED_BYTES, HASH_BYTES);
sigptr += NPACKED_BYTES + 2*HASH_BYTES;
}
H(c, c, HASH_BYTES * ROUNDS * 2);
if (memcmp(c, sigma0, HASH_BYTES)) {
memset(m, 0, smlen);
*mlen = 0;
return 1;
}
/* If verification was successful, move the message to the right place. */
memmove(m, m + SIG_LEN, *mlen);
return 0;
}