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pqcrypto/crypto_kem/ntruhps4096821/clean/poly.c
John Schanck 0d7743d576 Update NTRU (#311)
* Update NTRU

version: https://github.com/jschanck/ntru/tree/485dde03

* Fixed ntruhrss701/clean/Makefile.Microsoft_nmake
2021-03-24 21:02:46 +00:00

68 lines
2.1 KiB
C

#include "poly.h"
/* Map {0, 1, 2} -> {0,1,q-1} in place */
void PQCLEAN_NTRUHPS4096821_CLEAN_poly_Z3_to_Zq(poly *r) {
int i;
for (i = 0; i < NTRU_N; i++) {
r->coeffs[i] = r->coeffs[i] | ((-(r->coeffs[i] >> 1)) & (NTRU_Q - 1));
}
}
/* Map {0, 1, q-1} -> {0,1,2} in place */
void PQCLEAN_NTRUHPS4096821_CLEAN_poly_trinary_Zq_to_Z3(poly *r) {
int i;
for (i = 0; i < NTRU_N; i++) {
r->coeffs[i] = MODQ(r->coeffs[i]);
r->coeffs[i] = 3 & (r->coeffs[i] ^ (r->coeffs[i] >> (NTRU_LOGQ - 1)));
}
}
void PQCLEAN_NTRUHPS4096821_CLEAN_poly_Sq_mul(poly *r, const poly *a, const poly *b) {
PQCLEAN_NTRUHPS4096821_CLEAN_poly_Rq_mul(r, a, b);
PQCLEAN_NTRUHPS4096821_CLEAN_poly_mod_q_Phi_n(r);
}
void PQCLEAN_NTRUHPS4096821_CLEAN_poly_S3_mul(poly *r, const poly *a, const poly *b) {
PQCLEAN_NTRUHPS4096821_CLEAN_poly_Rq_mul(r, a, b);
PQCLEAN_NTRUHPS4096821_CLEAN_poly_mod_3_Phi_n(r);
}
static void PQCLEAN_NTRUHPS4096821_CLEAN_poly_R2_inv_to_Rq_inv(poly *r, const poly *ai, const poly *a) {
int i;
poly b, c;
poly s;
// for 0..4
// ai = ai * (2 - a*ai) mod q
for (i = 0; i < NTRU_N; i++) {
b.coeffs[i] = -(a->coeffs[i]);
}
for (i = 0; i < NTRU_N; i++) {
r->coeffs[i] = ai->coeffs[i];
}
PQCLEAN_NTRUHPS4096821_CLEAN_poly_Rq_mul(&c, r, &b);
c.coeffs[0] += 2; // c = 2 - a*ai
PQCLEAN_NTRUHPS4096821_CLEAN_poly_Rq_mul(&s, &c, r); // s = ai*c
PQCLEAN_NTRUHPS4096821_CLEAN_poly_Rq_mul(&c, &s, &b);
c.coeffs[0] += 2; // c = 2 - a*s
PQCLEAN_NTRUHPS4096821_CLEAN_poly_Rq_mul(r, &c, &s); // r = s*c
PQCLEAN_NTRUHPS4096821_CLEAN_poly_Rq_mul(&c, r, &b);
c.coeffs[0] += 2; // c = 2 - a*r
PQCLEAN_NTRUHPS4096821_CLEAN_poly_Rq_mul(&s, &c, r); // s = r*c
PQCLEAN_NTRUHPS4096821_CLEAN_poly_Rq_mul(&c, &s, &b);
c.coeffs[0] += 2; // c = 2 - a*s
PQCLEAN_NTRUHPS4096821_CLEAN_poly_Rq_mul(r, &c, &s); // r = s*c
}
void PQCLEAN_NTRUHPS4096821_CLEAN_poly_Rq_inv(poly *r, const poly *a) {
poly ai2;
PQCLEAN_NTRUHPS4096821_CLEAN_poly_R2_inv(&ai2, a);
PQCLEAN_NTRUHPS4096821_CLEAN_poly_R2_inv_to_Rq_inv(r, &ai2, a);
}