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pqcrypto/crypto_sign/dilithium2/clean/sign.c
Thom Wiggers 00b17e0740
Use PQClean int guidelines
2019-12-09 12:05:25 +01:00

425 lines
14 KiB
C
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#include <stdint.h>
#include <string.h>
#include "fips202.h"
#include "packing.h"
#include "params.h"
#include "poly.h"
#include "polyvec.h"
#include "randombytes.h"
#include "sign.h"
#include "symmetric.h"
/*************************************************
* Name: PQCLEAN_DILITHIUM2_CLEAN_expand_mat
*
* Description: Implementation of ExpandA. Generates matrix A with uniformly
* random coefficients a_{i,j} by performing rejection
* sampling on the output stream of SHAKE128(rho|i|j).
*
* Arguments: - polyvecl mat[K]: output matrix
* - const uint8_t rho[]: byte array containing seed rho
**************************************************/
void PQCLEAN_DILITHIUM2_CLEAN_expand_mat(polyvecl mat[K], const uint8_t rho[SEEDBYTES]) {
for (size_t i = 0; i < K; ++i) {
for (size_t j = 0; j < L; ++j) {
PQCLEAN_DILITHIUM2_CLEAN_poly_uniform(&mat[i].vec[j], rho, (uint16_t)((i << 8) + j));
}
}
}
/*************************************************
* Name: PQCLEAN_DILITHIUM2_CLEAN_challenge
*
* Description: Implementation of H. Samples polynomial with 60 nonzero
* coefficients in {-1,1} using the output stream of
* SHAKE256(mu|w1).
*
* Arguments: - poly *c: pointer to output polynomial
* - const uint8_t mu[]: byte array containing mu
* - const polyveck *w1: pointer to vector w1
**************************************************/
void PQCLEAN_DILITHIUM2_CLEAN_challenge(poly *c,
const uint8_t mu[CRHBYTES],
const polyveck *w1) {
uint64_t signs;
uint8_t inbuf[CRHBYTES + K * POLW1_SIZE_PACKED];
uint8_t outbuf[SHAKE256_RATE];
shake256ctx state;
uint8_t b;
size_t pos;
for (size_t i = 0; i < CRHBYTES; ++i) {
inbuf[i] = mu[i];
}
for (size_t i = 0; i < K; ++i) {
PQCLEAN_DILITHIUM2_CLEAN_polyw1_pack(inbuf + CRHBYTES + i * POLW1_SIZE_PACKED, &w1->vec[i]);
}
shake256_absorb(&state, inbuf, sizeof(inbuf));
shake256_squeezeblocks(outbuf, 1, &state);
signs = 0;
for (size_t i = 0; i < 8; ++i) {
signs |= (uint64_t)outbuf[i] << 8 * i;
}
pos = 8;
for (size_t i = 0; i < N; ++i) {
c->coeffs[i] = 0;
}
for (size_t i = 196; i < 256; ++i) {
do {
if (pos >= SHAKE256_RATE) {
shake256_squeezeblocks(outbuf, 1, &state);
pos = 0;
}
b = outbuf[pos++];
} while (b > i);
c->coeffs[i] = c->coeffs[b];
c->coeffs[b] = 1;
c->coeffs[b] ^= -((int32_t)signs & 1) & (1 ^ (Q - 1));
signs >>= 1;
}
}
/*************************************************
* Name: PQCLEAN_DILITHIUM2_CLEAN_crypto_sign_keypair
*
* Description: Generates public and private key.
*
* Arguments: - uint8_t *pk: pointer to output public key (allocated
* array of PQCLEAN_DILITHIUM2_CLEAN_CRYPTO_PUBLICKEYBYTES bytes)
* - uint8_t *sk: pointer to output private key (allocated
* array of PQCLEAN_DILITHIUM2_CLEAN_CRYPTO_SECRETKEYBYTES bytes)
*
* Returns 0 (success)
**************************************************/
int PQCLEAN_DILITHIUM2_CLEAN_crypto_sign_keypair(uint8_t *pk, uint8_t *sk) {
uint8_t seedbuf[3 * SEEDBYTES];
uint8_t tr[CRHBYTES];
const uint8_t *rho, *rhoprime, *key;
uint16_t nonce = 0;
polyvecl mat[K];
polyvecl s1, s1hat;
polyveck s2, t, t1, t0;
/* Expand 32 bytes of randomness into rho, rhoprime and key */
randombytes(seedbuf, 3 * SEEDBYTES);
rho = seedbuf;
rhoprime = seedbuf + SEEDBYTES;
key = seedbuf + 2 * SEEDBYTES;
/* Expand matrix */
PQCLEAN_DILITHIUM2_CLEAN_expand_mat(mat, rho);
/* Sample short vectors s1 and s2 */
for (size_t i = 0; i < L; ++i) {
PQCLEAN_DILITHIUM2_CLEAN_poly_uniform_eta(&s1.vec[i], rhoprime, nonce++);
}
for (size_t i = 0; i < K; ++i) {
PQCLEAN_DILITHIUM2_CLEAN_poly_uniform_eta(&s2.vec[i], rhoprime, nonce++);
}
/* Matrix-vector multiplication */
s1hat = s1;
PQCLEAN_DILITHIUM2_CLEAN_polyvecl_ntt(&s1hat);
for (size_t i = 0; i < K; ++i) {
PQCLEAN_DILITHIUM2_CLEAN_polyvecl_pointwise_acc_invmontgomery(&t.vec[i], &mat[i], &s1hat);
PQCLEAN_DILITHIUM2_CLEAN_poly_reduce(&t.vec[i]);
PQCLEAN_DILITHIUM2_CLEAN_poly_invntt_montgomery(&t.vec[i]);
}
/* Add error vector s2 */
PQCLEAN_DILITHIUM2_CLEAN_polyveck_add(&t, &t, &s2);
/* Extract t1 and write public key */
PQCLEAN_DILITHIUM2_CLEAN_polyveck_freeze(&t);
PQCLEAN_DILITHIUM2_CLEAN_polyveck_power2round(&t1, &t0, &t);
PQCLEAN_DILITHIUM2_CLEAN_pack_pk(pk, rho, &t1);
/* Compute CRH(rho, t1) and write secret key */
crh(tr, pk, PQCLEAN_DILITHIUM2_CLEAN_CRYPTO_PUBLICKEYBYTES);
PQCLEAN_DILITHIUM2_CLEAN_pack_sk(sk, rho, key, tr, &s1, &s2, &t0);
return 0;
}
/*************************************************
* Name: PQCLEAN_DILITHIUM2_CLEAN_crypto_sign_signature
*
* Description: Compute signed message.
*
* Arguments: - uint8_t *sig: pointer to output signature (PQCLEAN_DILITHIUM2_CLEAN_CRYPTO_BYTES
* of len)
* - size_t *smlen: pointer to output length of signed message
* (should be PQCLEAN_DILITHIUM2_CLEAN_CRYPTO_BYTES)
* - uint8_t *m: pointer to message to be signed
* - size_t mlen: length of message
* - uint8_t *sk: pointer to bit-packed secret key
*
* Returns 0 (success)
**************************************************/
int PQCLEAN_DILITHIUM2_CLEAN_crypto_sign_signature(
uint8_t *sig, size_t *siglen,
const uint8_t *msg, size_t mlen,
const uint8_t *sk) {
uint8_t seedbuf[2 * SEEDBYTES + 3 * CRHBYTES];
uint8_t *rho, *tr, *key, *mu, *rhoprime;
uint32_t n;
uint16_t nonce = 0;
poly c, chat;
polyvecl mat[K], s1, y, yhat, z;
polyveck t0, s2, w, w1, w0;
polyveck h, cs2, ct0;
rho = seedbuf;
tr = rho + SEEDBYTES;
key = tr + CRHBYTES;
mu = key + SEEDBYTES;
rhoprime = mu + CRHBYTES;
PQCLEAN_DILITHIUM2_CLEAN_unpack_sk(rho, key, tr, &s1, &s2, &t0, sk);
// use incremental hash API instead of copying around buffers
/* Compute CRH(tr, msg) */
shake256incctx state;
shake256_inc_init(&state);
shake256_inc_absorb(&state, tr, CRHBYTES);
shake256_inc_absorb(&state, msg, mlen);
shake256_inc_finalize(&state);
shake256_inc_squeeze(mu, CRHBYTES, &state);
crh(rhoprime, key, SEEDBYTES + CRHBYTES);
/* Expand matrix and transform vectors */
PQCLEAN_DILITHIUM2_CLEAN_expand_mat(mat, rho);
PQCLEAN_DILITHIUM2_CLEAN_polyvecl_ntt(&s1);
PQCLEAN_DILITHIUM2_CLEAN_polyveck_ntt(&s2);
PQCLEAN_DILITHIUM2_CLEAN_polyveck_ntt(&t0);
rej:
/* Sample intermediate vector y */
for (size_t i = 0; i < L; ++i) {
PQCLEAN_DILITHIUM2_CLEAN_poly_uniform_gamma1m1(&y.vec[i], rhoprime, nonce++);
}
/* Matrix-vector multiplication */
yhat = y;
PQCLEAN_DILITHIUM2_CLEAN_polyvecl_ntt(&yhat);
for (size_t i = 0; i < K; ++i) {
PQCLEAN_DILITHIUM2_CLEAN_polyvecl_pointwise_acc_invmontgomery(&w.vec[i], &mat[i], &yhat);
PQCLEAN_DILITHIUM2_CLEAN_poly_reduce(&w.vec[i]);
PQCLEAN_DILITHIUM2_CLEAN_poly_invntt_montgomery(&w.vec[i]);
}
/* Decompose w and call the random oracle */
PQCLEAN_DILITHIUM2_CLEAN_polyveck_csubq(&w);
PQCLEAN_DILITHIUM2_CLEAN_polyveck_decompose(&w1, &w0, &w);
PQCLEAN_DILITHIUM2_CLEAN_challenge(&c, mu, &w1);
chat = c;
PQCLEAN_DILITHIUM2_CLEAN_poly_ntt(&chat);
/* Check that subtracting cs2 does not change high bits of w and low bits
* do not reveal secret information */
for (size_t i = 0; i < K; ++i) {
PQCLEAN_DILITHIUM2_CLEAN_poly_pointwise_invmontgomery(&cs2.vec[i], &chat, &s2.vec[i]);
PQCLEAN_DILITHIUM2_CLEAN_poly_invntt_montgomery(&cs2.vec[i]);
}
PQCLEAN_DILITHIUM2_CLEAN_polyveck_sub(&w0, &w0, &cs2);
PQCLEAN_DILITHIUM2_CLEAN_polyveck_freeze(&w0);
if (PQCLEAN_DILITHIUM2_CLEAN_polyveck_chknorm(&w0, GAMMA2 - BETA)) {
goto rej;
}
/* Compute z, reject if it reveals secret */
for (size_t i = 0; i < L; ++i) {
PQCLEAN_DILITHIUM2_CLEAN_poly_pointwise_invmontgomery(&z.vec[i], &chat, &s1.vec[i]);
PQCLEAN_DILITHIUM2_CLEAN_poly_invntt_montgomery(&z.vec[i]);
}
PQCLEAN_DILITHIUM2_CLEAN_polyvecl_add(&z, &z, &y);
PQCLEAN_DILITHIUM2_CLEAN_polyvecl_freeze(&z);
if (PQCLEAN_DILITHIUM2_CLEAN_polyvecl_chknorm(&z, GAMMA1 - BETA)) {
goto rej;
}
/* Compute hints for w1 */
for (size_t i = 0; i < K; ++i) {
PQCLEAN_DILITHIUM2_CLEAN_poly_pointwise_invmontgomery(&ct0.vec[i], &chat, &t0.vec[i]);
PQCLEAN_DILITHIUM2_CLEAN_poly_invntt_montgomery(&ct0.vec[i]);
}
PQCLEAN_DILITHIUM2_CLEAN_polyveck_csubq(&ct0);
if (PQCLEAN_DILITHIUM2_CLEAN_polyveck_chknorm(&ct0, GAMMA2)) {
goto rej;
}
PQCLEAN_DILITHIUM2_CLEAN_polyveck_add(&w0, &w0, &ct0);
PQCLEAN_DILITHIUM2_CLEAN_polyveck_csubq(&w0);
n = PQCLEAN_DILITHIUM2_CLEAN_polyveck_make_hint(&h, &w0, &w1);
if (n > OMEGA) {
goto rej;
}
/* Write signature */
PQCLEAN_DILITHIUM2_CLEAN_pack_sig(sig, &z, &h, &c);
*siglen = PQCLEAN_DILITHIUM2_CLEAN_CRYPTO_BYTES;
return 0;
}
/*************************************************
* Name: PQCLEAN_DILITHIUM2_CLEAN_crypto_sign
*
* Description: Compute signed message.
*
* Arguments: - uint8_t *sm: pointer to output signed message (allocated
* array with PQCLEAN_DILITHIUM2_CLEAN_CRYPTO_BYTES + mlen bytes),
* can be equal to m
* - size_t *smlen: pointer to output length of signed
* message
* - const uint8_t *m: pointer to message to be signed
* - size_t mlen: length of message
* - const uint8_t *sk: pointer to bit-packed secret key
*
* Returns 0 (success)
**************************************************/
int PQCLEAN_DILITHIUM2_CLEAN_crypto_sign(
uint8_t *sm, size_t *smlen,
const uint8_t *m, size_t mlen,
const uint8_t *sk) {
int rc;
memmove(sm + PQCLEAN_DILITHIUM2_CLEAN_CRYPTO_BYTES, m, mlen);
rc = PQCLEAN_DILITHIUM2_CLEAN_crypto_sign_signature(sm, smlen, m, mlen, sk);
*smlen += mlen;
return rc;
}
/*************************************************
* Name: PQCLEAN_DILITHIUM2_CLEAN_crypto_sign_verify
*
* Description: Verify signed message.
*
* Arguments: - uint8_t *sig: signature
* - size_t siglen: length of signature (PQCLEAN_DILITHIUM2_CLEAN_CRYPTO_BYTES)
* - uint8_t *m: pointer to message
* - size_t *mlen: pointer to output length of message
* - uint8_t *pk: pointer to bit-packed public key
*
* Returns 0 if signed message could be verified correctly and -1 otherwise
**************************************************/
int PQCLEAN_DILITHIUM2_CLEAN_crypto_sign_verify(
const uint8_t *sig, size_t siglen,
const uint8_t *m, size_t mlen, const uint8_t *pk) {
uint8_t rho[SEEDBYTES];
uint8_t mu[CRHBYTES];
poly c, chat, cp;
polyvecl mat[K], z;
polyveck t1, w1, h, tmp1, tmp2;
if (siglen < PQCLEAN_DILITHIUM2_CLEAN_CRYPTO_BYTES) {
return -1;
}
PQCLEAN_DILITHIUM2_CLEAN_unpack_pk(rho, &t1, pk);
if (PQCLEAN_DILITHIUM2_CLEAN_unpack_sig(&z, &h, &c, sig)) {
return -1;
}
if (PQCLEAN_DILITHIUM2_CLEAN_polyvecl_chknorm(&z, GAMMA1 - BETA)) {
return -1;
}
/* Compute CRH(CRH(rho, t1), msg) */
crh(mu, pk, PQCLEAN_DILITHIUM2_CLEAN_CRYPTO_PUBLICKEYBYTES);
shake256incctx state;
shake256_inc_init(&state);
shake256_inc_absorb(&state, mu, CRHBYTES);
shake256_inc_absorb(&state, m, mlen);
shake256_inc_finalize(&state);
shake256_inc_squeeze(mu, CRHBYTES, &state);
/* Matrix-vector multiplication; compute Az - c2^dt1 */
PQCLEAN_DILITHIUM2_CLEAN_expand_mat(mat, rho);
PQCLEAN_DILITHIUM2_CLEAN_polyvecl_ntt(&z);
for (size_t i = 0; i < K ; ++i) {
PQCLEAN_DILITHIUM2_CLEAN_polyvecl_pointwise_acc_invmontgomery(&tmp1.vec[i], &mat[i], &z);
}
chat = c;
PQCLEAN_DILITHIUM2_CLEAN_poly_ntt(&chat);
PQCLEAN_DILITHIUM2_CLEAN_polyveck_shiftl(&t1);
PQCLEAN_DILITHIUM2_CLEAN_polyveck_ntt(&t1);
for (size_t i = 0; i < K; ++i) {
PQCLEAN_DILITHIUM2_CLEAN_poly_pointwise_invmontgomery(&tmp2.vec[i], &chat, &t1.vec[i]);
}
PQCLEAN_DILITHIUM2_CLEAN_polyveck_sub(&tmp1, &tmp1, &tmp2);
PQCLEAN_DILITHIUM2_CLEAN_polyveck_reduce(&tmp1);
PQCLEAN_DILITHIUM2_CLEAN_polyveck_invntt_montgomery(&tmp1);
/* Reconstruct w1 */
PQCLEAN_DILITHIUM2_CLEAN_polyveck_csubq(&tmp1);
PQCLEAN_DILITHIUM2_CLEAN_polyveck_use_hint(&w1, &tmp1, &h);
/* Call random oracle and verify challenge */
PQCLEAN_DILITHIUM2_CLEAN_challenge(&cp, mu, &w1);
for (size_t i = 0; i < N; ++i) {
if (c.coeffs[i] != cp.coeffs[i]) {
return -1;
}
}
// All good
return 0;
}
/*************************************************
* Name: PQCLEAN_DILITHIUM2_CLEAN_crypto_sign_open
*
* Description: Verify signed message.
*
* Arguments: - uint8_t *m: pointer to output message (allocated
* array with smlen bytes), can be equal to sm
* - size_t *mlen: pointer to output length of message
* - const uint8_t *sm: pointer to signed message
* - size_t smlen: length of signed message
* - const uint8_t *pk: pointer to bit-packed public key
*
* Returns 0 if signed message could be verified correctly and -1 otherwise
**************************************************/
int PQCLEAN_DILITHIUM2_CLEAN_crypto_sign_open(
uint8_t *m, size_t *mlen,
const uint8_t *sm, size_t smlen,
const uint8_t *pk) {
if (smlen < PQCLEAN_DILITHIUM2_CLEAN_CRYPTO_BYTES) {
goto badsig;
}
*mlen = smlen - PQCLEAN_DILITHIUM2_CLEAN_CRYPTO_BYTES;
if (PQCLEAN_DILITHIUM2_CLEAN_crypto_sign_verify(sm, PQCLEAN_DILITHIUM2_CLEAN_CRYPTO_BYTES,
sm + PQCLEAN_DILITHIUM2_CLEAN_CRYPTO_BYTES, *mlen, pk)) {
goto badsig;
} else {
/* All good, copy msg, return 0 */
for (size_t i = 0; i < *mlen; ++i) {
m[i] = sm[PQCLEAN_DILITHIUM2_CLEAN_CRYPTO_BYTES + i];
}
return 0;
}
/* Signature verification failed */
badsig:
*mlen = (size_t) -1;
for (size_t i = 0; i < smlen; ++i) {
m[i] = 0;
}
return -1;
}
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