162 lines
6.3 KiB
C
162 lines
6.3 KiB
C
#include "ntt.h"
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#include "params.h"
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#include "reduce.h"
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#include <stdint.h>
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/* Code to generate PQCLEAN_KYBER102490S_CLEAN_zetas and PQCLEAN_KYBER102490S_CLEAN_zetas_inv used in the number-theoretic transform:
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#define KYBER_ROOT_OF_UNITY 17
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static const uint16_t tree[128] = {
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0, 64, 32, 96, 16, 80, 48, 112, 8, 72, 40, 104, 24, 88, 56, 120,
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4, 68, 36, 100, 20, 84, 52, 116, 12, 76, 44, 108, 28, 92, 60, 124,
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2, 66, 34, 98, 18, 82, 50, 114, 10, 74, 42, 106, 26, 90, 58, 122,
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6, 70, 38, 102, 22, 86, 54, 118, 14, 78, 46, 110, 30, 94, 62, 126,
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1, 65, 33, 97, 17, 81, 49, 113, 9, 73, 41, 105, 25, 89, 57, 121,
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5, 69, 37, 101, 21, 85, 53, 117, 13, 77, 45, 109, 29, 93, 61, 125,
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3, 67, 35, 99, 19, 83, 51, 115, 11, 75, 43, 107, 27, 91, 59, 123,
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7, 71, 39, 103, 23, 87, 55, 119, 15, 79, 47, 111, 31, 95, 63, 127
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};
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void init_ntt() {
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unsigned int i, j, k;
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int16_t tmp[128];
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tmp[0] = MONT;
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for(i = 1; i < 128; ++i)
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tmp[i] = fqmul(tmp[i-1], KYBER_ROOT_OF_UNITY*MONT % KYBER_Q);
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for(i = 0; i < 128; ++i)
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PQCLEAN_KYBER102490S_CLEAN_zetas[i] = tmp[tree[i]];
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k = 0;
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for(i = 64; i >= 1; i >>= 1)
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for(j = i; j < 2*i; ++j)
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PQCLEAN_KYBER102490S_CLEAN_zetas_inv[k++] = -tmp[128 - tree[j]];
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PQCLEAN_KYBER102490S_CLEAN_zetas_inv[127] = MONT * (MONT * (KYBER_Q - 1) * ((KYBER_Q - 1)/128) % KYBER_Q) % KYBER_Q;
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}
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*/
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const int16_t PQCLEAN_KYBER102490S_CLEAN_zetas[128] = {
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2285, 2571, 2970, 1812, 1493, 1422, 287, 202, 3158, 622, 1577, 182, 962,
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2127, 1855, 1468, 573, 2004, 264, 383, 2500, 1458, 1727, 3199, 2648, 1017,
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732, 608, 1787, 411, 3124, 1758, 1223, 652, 2777, 1015, 2036, 1491, 3047,
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1785, 516, 3321, 3009, 2663, 1711, 2167, 126, 1469, 2476, 3239, 3058, 830,
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107, 1908, 3082, 2378, 2931, 961, 1821, 2604, 448, 2264, 677, 2054, 2226,
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430, 555, 843, 2078, 871, 1550, 105, 422, 587, 177, 3094, 3038, 2869, 1574,
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1653, 3083, 778, 1159, 3182, 2552, 1483, 2727, 1119, 1739, 644, 2457, 349,
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418, 329, 3173, 3254, 817, 1097, 603, 610, 1322, 2044, 1864, 384, 2114, 3193,
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1218, 1994, 2455, 220, 2142, 1670, 2144, 1799, 2051, 794, 1819, 2475, 2459,
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478, 3221, 3021, 996, 991, 958, 1869, 1522, 1628
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};
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const int16_t PQCLEAN_KYBER102490S_CLEAN_zetas_inv[128] = {
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1701, 1807, 1460, 2371, 2338, 2333, 308, 108, 2851, 870, 854, 1510, 2535,
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1278, 1530, 1185, 1659, 1187, 3109, 874, 1335, 2111, 136, 1215, 2945, 1465,
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1285, 2007, 2719, 2726, 2232, 2512, 75, 156, 3000, 2911, 2980, 872, 2685,
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1590, 2210, 602, 1846, 777, 147, 2170, 2551, 246, 1676, 1755, 460, 291, 235,
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3152, 2742, 2907, 3224, 1779, 2458, 1251, 2486, 2774, 2899, 1103, 1275, 2652,
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1065, 2881, 725, 1508, 2368, 398, 951, 247, 1421, 3222, 2499, 271, 90, 853,
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1860, 3203, 1162, 1618, 666, 320, 8, 2813, 1544, 282, 1838, 1293, 2314, 552,
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2677, 2106, 1571, 205, 2918, 1542, 2721, 2597, 2312, 681, 130, 1602, 1871,
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829, 2946, 3065, 1325, 2756, 1861, 1474, 1202, 2367, 3147, 1752, 2707, 171,
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3127, 3042, 1907, 1836, 1517, 359, 758, 1441
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};
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/*************************************************
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* Name: fqmul
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*
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* Description: Multiplication followed by Montgomery reduction
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*
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* Arguments: - int16_t a: first factor
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* - int16_t b: second factor
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*
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* Returns 16-bit integer congruent to a*b*R^{-1} mod q
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**************************************************/
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static int16_t fqmul(int16_t a, int16_t b) {
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return PQCLEAN_KYBER102490S_CLEAN_montgomery_reduce((int32_t)a * b);
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}
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/*************************************************
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* Name: PQCLEAN_KYBER102490S_CLEAN_ntt
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*
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* Description: Inplace number-theoretic transform (NTT) in Rq
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* input is in standard order, output is in bitreversed order
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*
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* Arguments: - int16_t r[256]: pointer to input/output vector of elements
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* of Zq
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**************************************************/
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void PQCLEAN_KYBER102490S_CLEAN_ntt(int16_t r[256]) {
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unsigned int len, start, j, k;
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int16_t t, zeta;
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k = 1;
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for (len = 128; len >= 2; len >>= 1) {
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for (start = 0; start < 256; start = j + len) {
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zeta = PQCLEAN_KYBER102490S_CLEAN_zetas[k++];
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for (j = start; j < start + len; ++j) {
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t = fqmul(zeta, r[j + len]);
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r[j + len] = r[j] - t;
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r[j] = r[j] + t;
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}
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}
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}
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}
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/*************************************************
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* Name: invntt_tomont
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*
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* Description: Inplace inverse number-theoretic transform in Rq and
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* multiplication by Montgomery factor 2^16.
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* Input is in bitreversed order, output is in standard order
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*
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* Arguments: - int16_t r[256]: pointer to input/output vector of elements
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* of Zq
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**************************************************/
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void PQCLEAN_KYBER102490S_CLEAN_invntt(int16_t r[256]) {
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unsigned int start, len, j, k;
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int16_t t, zeta;
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k = 0;
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for (len = 2; len <= 128; len <<= 1) {
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for (start = 0; start < 256; start = j + len) {
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zeta = PQCLEAN_KYBER102490S_CLEAN_zetas_inv[k++];
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for (j = start; j < start + len; ++j) {
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t = r[j];
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r[j] = PQCLEAN_KYBER102490S_CLEAN_barrett_reduce(t + r[j + len]);
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r[j + len] = t - r[j + len];
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r[j + len] = fqmul(zeta, r[j + len]);
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}
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}
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}
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for (j = 0; j < 256; ++j) {
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r[j] = fqmul(r[j], PQCLEAN_KYBER102490S_CLEAN_zetas_inv[127]);
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}
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}
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/*************************************************
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* Name: PQCLEAN_KYBER102490S_CLEAN_basemul
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*
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* Description: Multiplication of polynomials in Zq[X]/(X^2-zeta)
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* used for multiplication of elements in Rq in NTT domain
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*
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* Arguments: - int16_t r[2]: pointer to the output polynomial
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* - const int16_t a[2]: pointer to the first factor
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* - const int16_t b[2]: pointer to the second factor
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* - int16_t zeta: integer defining the reduction polynomial
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**************************************************/
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void PQCLEAN_KYBER102490S_CLEAN_basemul(int16_t r[2],
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const int16_t a[2],
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const int16_t b[2],
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int16_t zeta) {
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r[0] = fqmul(a[1], b[1]);
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r[0] = fqmul(r[0], zeta);
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r[0] += fqmul(a[0], b[0]);
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r[1] = fqmul(a[0], b[1]);
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r[1] += fqmul(a[1], b[0]);
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}
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