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

86 lines
2.5 KiB
C

#include "mq.h"
#include "params.h"
/* Computes all products x_i * x_j, returns in reduced form */
inline static
void generate_quadratic_terms( gf31 * xij , const gf31 * x )
{
int i, j, k;
k=0;
for(i=0;i<N;i++) {
for(j=0;j<=i;j++) {
xij[k] = PQCLEAN_MQDSS48_CLEAN_mod31((gf31)(x[i]*x[j]));
k++;
}
}
}
/* Computes all terms (x_i * y_j) + (x_j * y_i), returns in reduced form */
inline static
void generate_xiyj_p_xjyi_terms( gf31 * xij , const gf31 * x , const gf31 * y )
{
int i, j, k;
k=0;
for(i=0;i<N;i++) {
for(j=0;j<=i;j++) {
xij[k] = PQCLEAN_MQDSS48_CLEAN_mod31((gf31)(x[i]*y[j]+x[j]*y[i]));
k++;
}
}
}
/* Evaluates the MQ function on a vector of N gf31 elements x (expected to be
in reduced 5-bit representation). Expects the coefficients in F to be in
signed representation (i.e. [-15, 15], packed bytewise).
Outputs M gf31 elements in unique 16-bit representation as fx. */
void PQCLEAN_MQDSS48_CLEAN_MQ(gf31 *fx, const gf31 *x, const signed char *F)
{
int i, j;
gf31 _xij[N*(N+1) >> 1];
int r[M] = {0};
generate_quadratic_terms(_xij, x);
for (i = 0; i < N; i += 2) {
for (j = 0; j < M; j++) {
r[j] += ((int)x[i])*((int)F[i*M + 2*j]) +
((int)x[i+1])*((int)F[i*M + 2*j + 1]);
}
}
for (i = 0; i < (N*(N+1)) >> 1; i += 2) {
for (j = 0; j < M; j++) {
r[j] += ((int)_xij[i])*((int)F[N*M + i*M + 2*j]) +
((int)_xij[i+1])*((int)F[N*M + i*M + 2*j + 1]);
}
}
for (i = 0; i < M; i++) {
fx[i] = PQCLEAN_MQDSS48_CLEAN_mod31((gf31)((r[i] >> 15) + (r[i] & 0x7FFF)));
}
}
/* Evaluates the bilinear polar form of the MQ function (i.e. G) on a vector of
N gf31 elements x (expected to be in reduced 5-bit representation). Expects
the coefficients in F to be in signed representation (i.e. [-15, 15], packed
bytewise). Outputs M gf31 elements in unique 16-bit representation as fx. */
void PQCLEAN_MQDSS48_CLEAN_G(gf31 *fx, const gf31 *x, const gf31 *y, const signed char *F)
{
int i, j;
gf31 _xij[N*(N+1) >> 1];
int r[M] = {0};
generate_xiyj_p_xjyi_terms(_xij, x, y);
for (i = 0; i < (N*(N+1)) >> 1; i += 2) {
for (j = 0; j < M; j++) {
r[j] += ((int)_xij[i])*((int)F[N*M + i*M + 2*j]) +
((int)_xij[i+1])*((int)F[N*M + i*M + 2*j + 1]);
}
}
for (i = 0; i < M; i++) {
fx[i] = PQCLEAN_MQDSS48_CLEAN_mod31((gf31)((r[i] >> 15) + (r[i] & 0x7FFF)));
}
}