gazagnaire.org
upstream: https://github.com/mirage/mirage-crypto
1/* Based on https://github.com/abeaumont/ocaml-chacha.git */
2
3#include "crypto.h"
4
5static inline void mc_chacha_quarterround(uint32_t *x, int a, int b, int c, int d) {
6 x[a] += x[b]; x[d] = rol32(x[d] ^ x[a], 16);
7 x[c] += x[d]; x[b] = rol32(x[b] ^ x[c], 12);
8 x[a] += x[b]; x[d] = rol32(x[d] ^ x[a], 8);
9 x[c] += x[d]; x[b] = rol32(x[b] ^ x[c], 7);
10}
11
12void mc_chacha_core_generic(int count, const uint32_t *src, uint32_t *dst) {
13 uint32_t x[16];
14 cpu_to_le32_array(x, src, 16);
15 for (int i = 0; i < count; i++) {
16 mc_chacha_quarterround(x, 0, 4, 8, 12);
17 mc_chacha_quarterround(x, 1, 5, 9, 13);
18 mc_chacha_quarterround(x, 2, 6, 10, 14);
19 mc_chacha_quarterround(x, 3, 7, 11, 15);
20
21 mc_chacha_quarterround(x, 0, 5, 10, 15);
22 mc_chacha_quarterround(x, 1, 6, 11, 12);
23 mc_chacha_quarterround(x, 2, 7, 8, 13);
24 mc_chacha_quarterround(x, 3, 4, 9, 14);
25 }
26 for (int i = 0; i < 16; i++) {
27 uint32_t xi = x[i];
28 uint32_t hj = cpu_to_le32(src[i]);
29 dst[i] = le32_to_cpu(xi + hj);
30 }
31}
32