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/* Copyright (c) 2014, Google Inc.
*
* Permission to use, copy, modify, and/or distribute this software for any
* purpose with or without fee is hereby granted, provided that the above
* copyright notice and this permission notice appear in all copies.
*
* THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
* WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
* MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY
* SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
* WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN ACTION
* OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF OR IN
* CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE. */
// Adapted from the public domain, estream code by D. Bernstein.
#include <openssl/chacha.h>
#include <assert.h>
#include <string.h>
#include <openssl/cpu.h>
#include "../internal.h"
#define U8TO32_LITTLE(p) \
(((uint32_t)((p)[0])) | ((uint32_t)((p)[1]) << 8) | \
((uint32_t)((p)[2]) << 16) | ((uint32_t)((p)[3]) << 24))
#if !defined(OPENSSL_NO_ASM) && \
(defined(OPENSSL_X86) || defined(OPENSSL_X86_64) || \
defined(OPENSSL_ARM) || defined(OPENSSL_AARCH64))
// ChaCha20_ctr32 is defined in asm/chacha-*.pl.
void ChaCha20_ctr32(uint8_t *out, const uint8_t *in, size_t in_len,
const uint32_t key[8], const uint32_t counter[4]);
void CRYPTO_chacha_20(uint8_t *out, const uint8_t *in, size_t in_len,
const uint8_t key[32], const uint8_t nonce[12],
uint32_t counter) {
assert(!buffers_alias(out, in_len, in, in_len) || in == out);
uint32_t counter_nonce[4]; counter_nonce[0] = counter;
counter_nonce[1] = U8TO32_LITTLE(nonce + 0);
counter_nonce[2] = U8TO32_LITTLE(nonce + 4);
counter_nonce[3] = U8TO32_LITTLE(nonce + 8);
const uint32_t *key_ptr = (const uint32_t *)key;
#if !defined(OPENSSL_X86) && !defined(OPENSSL_X86_64)
// The assembly expects the key to be four-byte aligned.
uint32_t key_u32[8];
if ((((uintptr_t)key) & 3) != 0) {
key_u32[0] = U8TO32_LITTLE(key + 0);
key_u32[1] = U8TO32_LITTLE(key + 4);
key_u32[2] = U8TO32_LITTLE(key + 8);
key_u32[3] = U8TO32_LITTLE(key + 12);
key_u32[4] = U8TO32_LITTLE(key + 16);
key_u32[5] = U8TO32_LITTLE(key + 20);
key_u32[6] = U8TO32_LITTLE(key + 24);
key_u32[7] = U8TO32_LITTLE(key + 28);
key_ptr = key_u32;
}
#endif
ChaCha20_ctr32(out, in, in_len, key_ptr, counter_nonce);
}
#else
// sigma contains the ChaCha constants, which happen to be an ASCII string.
static const uint8_t sigma[16] = { 'e', 'x', 'p', 'a', 'n', 'd', ' ', '3',
'2', '-', 'b', 'y', 't', 'e', ' ', 'k' };
#define ROTATE(v, n) (((v) << (n)) | ((v) >> (32 - (n))))
#define U32TO8_LITTLE(p, v) \
{ \
(p)[0] = (v >> 0) & 0xff; \
(p)[1] = (v >> 8) & 0xff; \
(p)[2] = (v >> 16) & 0xff; \
(p)[3] = (v >> 24) & 0xff; \
}
// QUARTERROUND updates a, b, c, d with a ChaCha "quarter" round.
#define QUARTERROUND(a, b, c, d) \
x[a] += x[b]; x[d] = ROTATE(x[d] ^ x[a], 16); \
x[c] += x[d]; x[b] = ROTATE(x[b] ^ x[c], 12); \
x[a] += x[b]; x[d] = ROTATE(x[d] ^ x[a], 8); \
x[c] += x[d]; x[b] = ROTATE(x[b] ^ x[c], 7);
// chacha_core performs 20 rounds of ChaCha on the input words in
// |input| and writes the 64 output bytes to |output|.
static void chacha_core(uint8_t output[64], const uint32_t input[16]) {
uint32_t x[16];
int i;
OPENSSL_memcpy(x, input, sizeof(uint32_t) * 16);
for (i = 20; i > 0; i -= 2) {
QUARTERROUND(0, 4, 8, 12)
QUARTERROUND(1, 5, 9, 13)
QUARTERROUND(2, 6, 10, 14)
QUARTERROUND(3, 7, 11, 15)
QUARTERROUND(0, 5, 10, 15)
QUARTERROUND(1, 6, 11, 12)
QUARTERROUND(2, 7, 8, 13)
QUARTERROUND(3, 4, 9, 14)
}
for (i = 0; i < 16; ++i) {
x[i] += input[i];
}
for (i = 0; i < 16; ++i) {
U32TO8_LITTLE(output + 4 * i, x[i]);
}
}
void CRYPTO_chacha_20(uint8_t *out, const uint8_t *in, size_t in_len,
const uint8_t key[32], const uint8_t nonce[12],
uint32_t counter) {
assert(!buffers_alias(out, in_len, in, in_len) || in == out);
uint32_t input[16];
uint8_t buf[64];
size_t todo, i;
input[0] = U8TO32_LITTLE(sigma + 0);
input[1] = U8TO32_LITTLE(sigma + 4);
input[2] = U8TO32_LITTLE(sigma + 8);
input[3] = U8TO32_LITTLE(sigma + 12);
input[4] = U8TO32_LITTLE(key + 0);
input[5] = U8TO32_LITTLE(key + 4);
input[6] = U8TO32_LITTLE(key + 8);
input[7] = U8TO32_LITTLE(key + 12);
input[8] = U8TO32_LITTLE(key + 16);
input[9] = U8TO32_LITTLE(key + 20);
input[10] = U8TO32_LITTLE(key + 24);
input[11] = U8TO32_LITTLE(key + 28);
input[12] = counter;
input[13] = U8TO32_LITTLE(nonce + 0);
input[14] = U8TO32_LITTLE(nonce + 4);
input[15] = U8TO32_LITTLE(nonce + 8);
while (in_len > 0) {
todo = sizeof(buf);
if (in_len < todo) {
todo = in_len;
}
chacha_core(buf, input);
for (i = 0; i < todo; i++) {
out[i] = in[i] ^ buf[i];
}
out += todo;
in += todo;
in_len -= todo;
input[12]++;
}
}
#endif
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