| /* |
| * ChaCha20 256-bit cipher algorithm, RFC7539 |
| * |
| * Copyright (C) 2015 Martin Willi |
| * |
| * This program is free software; you can redistribute it and/or modify |
| * it under the terms of the GNU General Public License as published by |
| * the Free Software Foundation; either version 2 of the License, or |
| * (at your option) any later version. |
| */ |
| |
| #include <linux/kernel.h> |
| #include <linux/export.h> |
| #include <linux/bitops.h> |
| #include <linux/cryptohash.h> |
| #include <asm/unaligned.h> |
| #include <crypto/chacha20.h> |
| |
| static inline u32 rotl32(u32 v, u8 n) |
| { |
| return (v << n) | (v >> (sizeof(v) * 8 - n)); |
| } |
| |
| extern void chacha20_block(u32 *state, void *stream) |
| { |
| u32 x[16], *out = stream; |
| int i; |
| |
| for (i = 0; i < ARRAY_SIZE(x); i++) |
| x[i] = state[i]; |
| |
| for (i = 0; i < 20; i += 2) { |
| x[0] += x[4]; x[12] = rotl32(x[12] ^ x[0], 16); |
| x[1] += x[5]; x[13] = rotl32(x[13] ^ x[1], 16); |
| x[2] += x[6]; x[14] = rotl32(x[14] ^ x[2], 16); |
| x[3] += x[7]; x[15] = rotl32(x[15] ^ x[3], 16); |
| |
| x[8] += x[12]; x[4] = rotl32(x[4] ^ x[8], 12); |
| x[9] += x[13]; x[5] = rotl32(x[5] ^ x[9], 12); |
| x[10] += x[14]; x[6] = rotl32(x[6] ^ x[10], 12); |
| x[11] += x[15]; x[7] = rotl32(x[7] ^ x[11], 12); |
| |
| x[0] += x[4]; x[12] = rotl32(x[12] ^ x[0], 8); |
| x[1] += x[5]; x[13] = rotl32(x[13] ^ x[1], 8); |
| x[2] += x[6]; x[14] = rotl32(x[14] ^ x[2], 8); |
| x[3] += x[7]; x[15] = rotl32(x[15] ^ x[3], 8); |
| |
| x[8] += x[12]; x[4] = rotl32(x[4] ^ x[8], 7); |
| x[9] += x[13]; x[5] = rotl32(x[5] ^ x[9], 7); |
| x[10] += x[14]; x[6] = rotl32(x[6] ^ x[10], 7); |
| x[11] += x[15]; x[7] = rotl32(x[7] ^ x[11], 7); |
| |
| x[0] += x[5]; x[15] = rotl32(x[15] ^ x[0], 16); |
| x[1] += x[6]; x[12] = rotl32(x[12] ^ x[1], 16); |
| x[2] += x[7]; x[13] = rotl32(x[13] ^ x[2], 16); |
| x[3] += x[4]; x[14] = rotl32(x[14] ^ x[3], 16); |
| |
| x[10] += x[15]; x[5] = rotl32(x[5] ^ x[10], 12); |
| x[11] += x[12]; x[6] = rotl32(x[6] ^ x[11], 12); |
| x[8] += x[13]; x[7] = rotl32(x[7] ^ x[8], 12); |
| x[9] += x[14]; x[4] = rotl32(x[4] ^ x[9], 12); |
| |
| x[0] += x[5]; x[15] = rotl32(x[15] ^ x[0], 8); |
| x[1] += x[6]; x[12] = rotl32(x[12] ^ x[1], 8); |
| x[2] += x[7]; x[13] = rotl32(x[13] ^ x[2], 8); |
| x[3] += x[4]; x[14] = rotl32(x[14] ^ x[3], 8); |
| |
| x[10] += x[15]; x[5] = rotl32(x[5] ^ x[10], 7); |
| x[11] += x[12]; x[6] = rotl32(x[6] ^ x[11], 7); |
| x[8] += x[13]; x[7] = rotl32(x[7] ^ x[8], 7); |
| x[9] += x[14]; x[4] = rotl32(x[4] ^ x[9], 7); |
| } |
| |
| for (i = 0; i < ARRAY_SIZE(x); i++) |
| out[i] = cpu_to_le32(x[i] + state[i]); |
| |
| state[12]++; |
| } |
| EXPORT_SYMBOL(chacha20_block); |