rivide 1.1.3

Official Rust idiomatic and zero-allocation bindings for the Rivide Post-Quantum Cryptography (NIST FIPS 203 ML-KEM & NIST FIPS 204 ML-DSA) C99 Library.
Documentation 
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138

/*
 * SPDX-License-Identifier: MIT
 *
 * Rivide Post-Quantum Cryptography Library
 * Copyright (C) 2026 Moh. Ananda Firmansyah Putra
 *
 * Permission is hereby granted, free of charge, to any person obtaining a copy
 * of this software and associated documentation files (the "Software"), to deal
 * in the Software without restriction, including without limitation the rights
 * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
 * copies of the Software, and to permit persons to whom the Software is
 * furnished to do so, subject to the following conditions:
 *
 * The above copyright notice and this permission notice shall be included in all
 * copies or substantial portions of the Software.
 */

/**
 * @file dsa_ntt.c
 * @brief ML-DSA NTT, inverse NTT, and pointwise multiplication.
 *
 * Contains the precomputed zeta table and the iterative butterfly NTT/INTT
 * transforms over Z_q[X]/(X^256 + 1) with q = 8380417.
 */

#include "rivide/internal/dsa_ntt.h"

#include "rivide/internal/dsa_reduce.h"

/**
 * @brief NTT zeta table for q = 8380417.
 *
 * Precomputed roots of unity in Montgomery form, in bit-reversed order
 * for the iterative NTT butterfly. The primitive 512th root of unity
 * modulo q is zeta = 1753.
 */
const int32_t dsa_zetas[DSA_N] = {
    0,        25847,    -2608894, -518909,  237124,   -777960,  -876248,  466468,   1826347,
    2353451,  -359251,  -2091905, 3119733,  -2884855, 3111497,  2680103,  2725464,  1024112,
    -1079900, 3585928,  -549488,  -1119584, 2619752,  -2108549, -2118186, -3859737, -1399561,
    -3277672, 1757237,  -19422,   4010497,  280005,   2706023,  95776,    3077325,  3530437,
    -1661693, -3592148, -2537516, 3915439,  -3861115, -3043716, 3574422,  -2867647, 3539968,
    -300467,  2348700,  -539299,  -1699267, -1643818, 3505694,  -3821735, 3507263,  -2140649,
    -1600420, 3699596,  811944,   531354,   954230,   3881043,  3900724,  -2556880, 2071892,
    -2797779, -3930395, -1528703, -3677745, -3041255, -1452451, 3475950,  2176455,  -1585221,
    -1257611, 1939314,  -4083598, -1000202, -3190144, -3157330, -3632928, 126922,   3412210,
    -983419,  2147896,  2715295,  -2967645, -3693493, -411027,  -2477047, -671102,  -1228525,
    -22981,   -1308169, -381987,  1349076,  1852771,  -1430430, -3343383, 264944,   508951,
    3097992,  44288,    -1100098, 904516,   3958618,  -3724342, -8578,    1653064,  -3249728,
    2389356,  -210977,  759969,   -1316856, 189548,   -3553272, 3159746,  -1851402, -2409325,
    -177440,  1315589,  1341330,  1285669,  -1584928, -812732,  -1439742, -3019102, -3881060,
    -3628969, 3839961,  2091667,  3407706,  2316500,  3817976,  -3342478, 2244091,  -2446433,
    -3562462, 266997,   2434439,  -1235728, 3513181,  -3520352, -3759364, -1197226, -3193378,
    900702,   1859098,  909542,   819034,   495491,   -1613174, -43260,   -522500,  -655327,
    -3122442, 2031748,  3207046,  -3556995, -525098,  -768622,  -3595838, 342297,   286988,
    -2437823, 4108315,  3437287,  -3342277, 1735879,  203044,   2842341,  2691481,  -2590150,
    1265009,  4055324,  1247620,  2486353,  1595974,  -3767016, 1250494,  2635921,  -3548272,
    -2994039, 1869119,  1903435,  -1050970, -1333058, 1237275,  -3318210, -1430225, -451100,
    1312455,  3306115,  -1962642, -1279661, 1917081,  -2546312, -1374803, 1500165,  777191,
    2235880,  3406031,  -542412,  -2831860, -1671176, -1846953, -2584293, -3724270, 594136,
    -3776993, -2013608, 2432395,  2454455,  -164721,  1957272,  3369112,  185531,   -1207385,
    -3183426, 162844,   1616392,  3014001,  810149,   1652634,  -3694233, -1799107, -3038916,
    3523897,  3866901,  269760,   2213111,  -975884,  1717735,  472078,   -426683,  1723600,
    -1803090, 1910376,  -1667432, -1104333, -260646,  -3833893, -2939036, -2235985, -420899,
    -2286327, 183443,   -976891,  1612842,  -3545687, -554416,  3919660,  -48306,   -1362209,
    3937738,  1400424,  -846154,  1976782};

/**
 * @brief In-place forward NTT for Dilithium polynomials.
 *
 * @param[in,out] p Polynomial structure to transform in-place.
 */
void dsa_poly_ntt(dsa_poly_t *p) {
    unsigned int len, start, j, k;
    int32_t zeta, t;

    k = 0;
    for (len = 128; len >= 1; len >>= 1) {
        for (start = 0; start < DSA_N; start += 2 * len) {
            zeta = dsa_zetas[++k];
            for (j = start; j < start + len; j++) {
                t = dsa_montgomery_reduce((int64_t)zeta * p->coeffs[j + len]);
                p->coeffs[j + len] = p->coeffs[j] - t;
                p->coeffs[j] = p->coeffs[j] + t;
            }
        }
    }
}

/**
 * @brief In-place inverse NTT for Dilithium polynomials.
 *
 * @param[in,out] p Polynomial structure to transform in-place.
 */
void dsa_poly_invntt(dsa_poly_t *p) {
    unsigned int len, start, j, k;
    int32_t zeta, t;
    const int32_t f = 41978; /* 256^{-1} mod q in Montgomery form. */

    k = 256;
    for (len = 1; len < DSA_N; len <<= 1) {
        for (start = 0; start < DSA_N; start += 2 * len) {
            zeta = dsa_zetas[--k];
            for (j = start; j < start + len; j++) {
                t = p->coeffs[j];
                p->coeffs[j] = t + p->coeffs[j + len];
                int32_t diff = p->coeffs[j + len] - t;
                p->coeffs[j + len] = dsa_montgomery_reduce((int64_t)zeta * diff);
            }
        }
    }

    for (j = 0; j < DSA_N; j++) {
        p->coeffs[j] = dsa_montgomery_reduce((int64_t)f * p->coeffs[j]);
    }
}

/**
 * @brief Pointwise multiplication of two polynomials in the NTT domain.
 *
 * @param[out] r Output polynomial buffer.
 * @param[in]  a First input polynomial in NTT domain.
 * @param[in]  b Second input polynomial in NTT domain.
 */
void dsa_poly_pointwise(dsa_poly_t *r, const dsa_poly_t *a, const dsa_poly_t *b) {
    unsigned int i;
    for (i = 0; i < DSA_N; i++) {
        r->coeffs[i] = dsa_montgomery_reduce((int64_t)a->coeffs[i] * b->coeffs[i]);
    }
}

void dsa_poly_tomont(dsa_poly_t *p) {
    static const int32_t r2 = 4193792;
    unsigned int i;
    for (i = 0; i < DSA_N; i++) {
        p->coeffs[i] = dsa_montgomery_reduce((int64_t)p->coeffs[i] * r2);
    }
}