--- /dev/null
+/* 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