142 lines
4.4 KiB
C
142 lines
4.4 KiB
C
/* Copyright (c) 2014, Google Inc.
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*
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* Permission to use, copy, modify, and/or distribute this software for any
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* purpose with or without fee is hereby granted, provided that the above
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* copyright notice and this permission notice appear in all copies.
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*
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* THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
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* WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
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* MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY
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* SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
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* WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN ACTION
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* OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF OR IN
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* CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE. */
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/* Adapted from the public domain, estream code by D. Bernstein. */
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#include <openssl/chacha.h>
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#include <openssl/cpu.h>
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#if defined(OPENSSL_WINDOWS) || !defined(OPENSSL_X86_64) && !defined(OPENSSL_X86)
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/* sigma contains the ChaCha constants, which happen to be an ASCII string. */
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static const char sigma[16] = "expand 32-byte k";
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#define ROTATE(v, n) (((v) << (n)) | ((v) >> (32 - (n))))
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#define XOR(v, w) ((v) ^ (w))
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#define PLUS(x, y) ((x) + (y))
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#define PLUSONE(v) (PLUS((v), 1))
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#define U32TO8_LITTLE(p, v) \
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{ \
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(p)[0] = (v >> 0) & 0xff; \
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(p)[1] = (v >> 8) & 0xff; \
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(p)[2] = (v >> 16) & 0xff; \
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(p)[3] = (v >> 24) & 0xff; \
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}
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#define U8TO32_LITTLE(p) \
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(((uint32_t)((p)[0])) | ((uint32_t)((p)[1]) << 8) | \
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((uint32_t)((p)[2]) << 16) | ((uint32_t)((p)[3]) << 24))
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/* QUARTERROUND updates a, b, c, d with a ChaCha "quarter" round. */
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#define QUARTERROUND(a,b,c,d) \
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x[a] = PLUS(x[a],x[b]); x[d] = ROTATE(XOR(x[d],x[a]),16); \
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x[c] = PLUS(x[c],x[d]); x[b] = ROTATE(XOR(x[b],x[c]),12); \
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x[a] = PLUS(x[a],x[b]); x[d] = ROTATE(XOR(x[d],x[a]), 8); \
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x[c] = PLUS(x[c],x[d]); x[b] = ROTATE(XOR(x[b],x[c]), 7);
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#if defined(OPENSSL_ARM)
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/* Defined in chacha_vec.c */
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void CRYPTO_chacha_20_neon(uint8_t *out, const uint8_t *in, size_t in_len,
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const uint8_t key[32], const uint8_t nonce[8],
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size_t counter);
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#endif
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/* chacha_core performs |num_rounds| rounds of ChaCha20 on the input words in
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* |input| and writes the 64 output bytes to |output|. */
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static void chacha_core(uint8_t output[64], const uint32_t input[16],
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int num_rounds) {
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uint32_t x[16];
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int i;
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memcpy(x, input, sizeof(uint32_t) * 16);
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for (i = 20; i > 0; i -= 2) {
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QUARTERROUND(0, 4, 8, 12)
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QUARTERROUND(1, 5, 9, 13)
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QUARTERROUND(2, 6, 10, 14)
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QUARTERROUND(3, 7, 11, 15)
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QUARTERROUND(0, 5, 10, 15)
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QUARTERROUND(1, 6, 11, 12)
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QUARTERROUND(2, 7, 8, 13)
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QUARTERROUND(3, 4, 9, 14)
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}
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for (i = 0; i < 16; ++i) {
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x[i] = PLUS(x[i], input[i]);
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}
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for (i = 0; i < 16; ++i) {
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U32TO8_LITTLE(output + 4 * i, x[i]);
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}
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}
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void CRYPTO_chacha_20(uint8_t *out, const uint8_t *in, size_t in_len,
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const uint8_t key[32], const uint8_t nonce[8],
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size_t counter) {
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uint32_t input[16];
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uint8_t buf[64];
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size_t todo, i;
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#if defined(OPENSSL_ARM)
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if (CRYPTO_is_NEON_capable() && ((intptr_t)in & 15) == 0 &&
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((intptr_t)out & 15) == 0) {
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CRYPTO_chacha_20_neon(out, in, in_len, key, nonce, counter);
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return;
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}
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#endif
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input[0] = U8TO32_LITTLE(sigma + 0);
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input[1] = U8TO32_LITTLE(sigma + 4);
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input[2] = U8TO32_LITTLE(sigma + 8);
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input[3] = U8TO32_LITTLE(sigma + 12);
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input[4] = U8TO32_LITTLE(key + 0);
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input[5] = U8TO32_LITTLE(key + 4);
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input[6] = U8TO32_LITTLE(key + 8);
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input[7] = U8TO32_LITTLE(key + 12);
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input[8] = U8TO32_LITTLE(key + 16);
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input[9] = U8TO32_LITTLE(key + 20);
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input[10] = U8TO32_LITTLE(key + 24);
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input[11] = U8TO32_LITTLE(key + 28);
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input[12] = counter;
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input[13] = ((uint64_t)counter) >> 32;
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input[14] = U8TO32_LITTLE(nonce + 0);
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input[15] = U8TO32_LITTLE(nonce + 4);
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while (in_len > 0) {
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todo = sizeof(buf);
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if (in_len < todo) {
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todo = in_len;
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}
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chacha_core(buf, input, 20);
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for (i = 0; i < todo; i++) {
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out[i] = in[i] ^ buf[i];
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}
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out += todo;
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in += todo;
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in_len -= todo;
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input[12]++;
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if (input[12] == 0) {
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input[13]++;
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}
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}
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}
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#endif /* OPENSSL_WINDOWS || !OPENSSL_X86_64 && !OPENSSL_X86 && !OPENSSL_ARM */
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