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mirror of https://github.com/henrydcase/pqc.git synced 2024-11-23 07:59:01 +00:00
pqcrypto/crypto_kem/ntruhps4096821/clean/packq.c
2019-04-29 09:41:17 -04:00

37 lines
1.3 KiB
C

#include "poly.h"
void PQCLEAN_NTRUHPS4096821_CLEAN_poly_Sq_tobytes(unsigned char *r, const poly *a) {
int i;
for (i = 0; i < NTRU_PACK_DEG / 2; i++) {
r[3 * i + 0] = (unsigned char) ( a->coeffs[2 * i + 0] & 0xff);
r[3 * i + 1] = (unsigned char) ((a->coeffs[2 * i + 0] >> 8) | ((a->coeffs[2 * i + 1] & 0x0f) << 4));
r[3 * i + 2] = (unsigned char) ((a->coeffs[2 * i + 1] >> 4));
}
}
void PQCLEAN_NTRUHPS4096821_CLEAN_poly_Sq_frombytes(poly *r, const unsigned char *a) {
int i;
for (i = 0; i < NTRU_PACK_DEG / 2; i++) {
r->coeffs[2 * i + 0] = (unsigned char) ((a[3 * i + 0] >> 0) | (((uint16_t)a[3 * i + 1] & 0x0f) << 8));
r->coeffs[2 * i + 1] = (unsigned char) ((a[3 * i + 1] >> 4) | (((uint16_t)a[3 * i + 2] & 0xff) << 4));
}
}
void PQCLEAN_NTRUHPS4096821_CLEAN_poly_Rq_sum_zero_tobytes(unsigned char *r, const poly *a) {
PQCLEAN_NTRUHPS4096821_CLEAN_poly_Sq_tobytes(r, a);
}
void PQCLEAN_NTRUHPS4096821_CLEAN_poly_Rq_sum_zero_frombytes(poly *r, const unsigned char *a) {
int i;
PQCLEAN_NTRUHPS4096821_CLEAN_poly_Sq_frombytes(r, a);
/* Set r[n-1] so that the sum of coefficients is zero mod q */
r->coeffs[NTRU_N - 1] = 0;
for (i = 0; i < NTRU_PACK_DEG; i++) {
r->coeffs[NTRU_N - 1] += r->coeffs[i];
}
r->coeffs[NTRU_N - 1] = MODQ(-(r->coeffs[NTRU_N - 1]));
}