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/* This Source Code Form is subject to the terms of the Mozilla Public
* License, v. 2.0. If a copy of the MPL was not distributed with this
* file, You can obtain one at http://mozilla.org/MPL/2.0/. */
/* Adopted from the public domain code in NaCl by djb. */
#include <string.h>
#include <stdio.h>
#include "prtypes.h"
#include "secport.h"
#include "chacha20.h"
#if defined(_MSC_VER)
#pragma intrinsic(_lrotl)
#define ROTL32(x, n) _lrotl(x, n)
#else
#define ROTL32(x, n) ((x << n) | (x >> ((8 * sizeof x) - n)))
#endif
#define ROTATE(v, c) ROTL32((v), (c))
#define U32TO8_LITTLE(p, v) \
{ \
(p)[0] = ((v)) & 0xff; \
(p)[1] = ((v) >> 8) & 0xff; \
(p)[2] = ((v) >> 16) & 0xff; \
(p)[3] = ((v) >> 24) & 0xff; \
}
#define U8TO32_LITTLE(p) \
(((PRUint32)((p)[0])) | ((PRUint32)((p)[1]) << 8) | \
((PRUint32)((p)[2]) << 16) | ((PRUint32)((p)[3]) << 24))
#define QUARTERROUND(x, a, b, c, d) \
x[a] = x[a] + x[b]; \
x[d] = ROTATE(x[d] ^ x[a], 16); \
x[c] = x[c] + x[d]; \
x[b] = ROTATE(x[b] ^ x[c], 12); \
x[a] = x[a] + x[b]; \
x[d] = ROTATE(x[d] ^ x[a], 8); \
x[c] = x[c] + x[d]; \
x[b] = ROTATE(x[b] ^ x[c], 7);
static void
ChaChaCore(unsigned char output[64], const PRUint32 input[16], int num_rounds)
{
PRUint32 x[16];
int i;
PORT_Memcpy(x, input, sizeof(PRUint32) * 16);
for (i = num_rounds; i > 0; i -= 2) {
QUARTERROUND(x, 0, 4, 8, 12)
QUARTERROUND(x, 1, 5, 9, 13)
QUARTERROUND(x, 2, 6, 10, 14)
QUARTERROUND(x, 3, 7, 11, 15)
QUARTERROUND(x, 0, 5, 10, 15)
QUARTERROUND(x, 1, 6, 11, 12)
QUARTERROUND(x, 2, 7, 8, 13)
QUARTERROUND(x, 3, 4, 9, 14)
}
for (i = 0; i < 16; ++i) {
x[i] = x[i] + input[i];
}
for (i = 0; i < 16; ++i) {
U32TO8_LITTLE(output + 4 * i, x[i]);
}
}
static const unsigned char sigma[16] = "expand 32-byte k";
void
ChaCha20XOR(unsigned char *out, const unsigned char *in, unsigned int inLen,
const unsigned char key[32], const unsigned char nonce[12],
uint32_t counter)
{
unsigned char block[64];
PRUint32 input[16];
unsigned int i;
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[0] = U8TO32_LITTLE(sigma + 0);
input[1] = U8TO32_LITTLE(sigma + 4);
input[2] = U8TO32_LITTLE(sigma + 8);
input[3] = U8TO32_LITTLE(sigma + 12);
input[12] = counter;
input[13] = U8TO32_LITTLE(nonce + 0);
input[14] = U8TO32_LITTLE(nonce + 4);
input[15] = U8TO32_LITTLE(nonce + 8);
while (inLen >= 64) {
ChaChaCore(block, input, 20);
for (i = 0; i < 64; i++) {
out[i] = in[i] ^ block[i];
}
input[12]++;
inLen -= 64;
in += 64;
out += 64;
}
if (inLen > 0) {
ChaChaCore(block, input, 20);
for (i = 0; i < inLen; i++) {
out[i] = in[i] ^ block[i];
}
}
}
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