208 строки
6.4 KiB
C
208 строки
6.4 KiB
C
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/*
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* This code is based on an OpenSSL implementation of chacha20.
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* Hence, the copyright below applies.
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*
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*/
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/* ====================================================================
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* Copyright (c) 2011-2013 The OpenSSL Project. All rights reserved.
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*
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* Redistribution and use in source and binary forms, with or without
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* modification, are permitted provided that the following conditions
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* are met:
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*
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* 1. Redistributions of source code must retain the above copyright
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* notice, this list of conditions and the following disclaimer.
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*
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* 2. Redistributions in binary form must reproduce the above copyright
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* notice, this list of conditions and the following disclaimer in
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* the documentation and/or other materials provided with the
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* distribution.
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*
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* 3. All advertising materials mentioning features or use of this
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* software must display the following acknowledgment:
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* "This product includes software developed by the OpenSSL Project
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* for use in the OpenSSL Toolkit. (http://www.OpenSSL.org/)"
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*
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* 4. The names "OpenSSL Toolkit" and "OpenSSL Project" must not be used to
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* endorse or promote products derived from this software without
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* prior written permission. For written permission, please contact
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* licensing@OpenSSL.org.
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*
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* 5. Products derived from this software may not be called "OpenSSL"
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* nor may "OpenSSL" appear in their names without prior written
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* permission of the OpenSSL Project.
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*
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* 6. Redistributions of any form whatsoever must retain the following
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* acknowledgment:
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* "This product includes software developed by the OpenSSL Project
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* for use in the OpenSSL Toolkit (http://www.OpenSSL.org/)"
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*
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* THIS SOFTWARE IS PROVIDED BY THE OpenSSL PROJECT ``AS IS'' AND ANY
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* EXPRESSED OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
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* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
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* PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE OpenSSL PROJECT OR
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* ITS CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
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* SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
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* NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
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* LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
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* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT,
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* STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
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* ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED
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* OF THE POSSIBILITY OF SUCH DAMAGE.
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* ====================================================================
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*/
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/* Adapted from the public domain code by D. Bernstein from SUPERCOP. */
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#include <stdint.h>
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#include <string.h>
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#include "chacha.h"
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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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{ (p)[0] = (v >> 0) & 0xff; (p)[1] = (v >> 8) & 0xff; \
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(p)[2] = (v >> 16) & 0xff; (p)[3] = (v >> 24) & 0xff; }
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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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/* 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(unsigned char output[64], const uint32_t input[16],
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int num_rounds)
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{
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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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{
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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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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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void CRYPTO_chacha_20(unsigned char *out,
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const unsigned char *in, size_t in_len,
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const unsigned char key[32],
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const unsigned char nonce[12],
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uint32_t counter)
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{
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uint32_t input[16];
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unsigned char buf[64];
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size_t todo, i;
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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] = U8TO32_LITTLE(nonce + 0);
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input[14] = U8TO32_LITTLE(nonce + 4);
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input[15] = U8TO32_LITTLE(nonce + 8);
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while (in_len > 0)
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{
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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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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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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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void CRYPTO_chacha_20_keystream(unsigned char *out,
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size_t out_len,
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const unsigned char key[32],
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const unsigned char nonce[12],
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uint32_t counter)
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{
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uint32_t input[16];
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unsigned char buf[64];
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size_t todo, i;
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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] = U8TO32_LITTLE(nonce + 0);
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input[14] = U8TO32_LITTLE(nonce + 4);
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input[15] = U8TO32_LITTLE(nonce + 8);
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while (out_len > 0)
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{
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todo = sizeof(buf);
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if (out_len < todo)
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todo = out_len;
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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] = buf[i];
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out += todo;
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out_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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