crypto/chacha/chacha_enc.c

   1 /* ====================================================================
   2  * Copyright (c) 2011-2013 The OpenSSL Project.  All rights reserved.
   3  *
   4  * Redistribution and use in source and binary forms, with or without
   5  * modification, are permitted provided that the following conditions
   6  * are met:
   7  *
   8  * 1. Redistributions of source code must retain the above copyright
   9  *    notice, this list of conditions and the following disclaimer.
  10  *
  11  * 2. Redistributions in binary form must reproduce the above copyright
  12  *    notice, this list of conditions and the following disclaimer in
  13  *    the documentation and/or other materials provided with the
  14  *    distribution.
  15  *
  16  * 3. All advertising materials mentioning features or use of this
  17  *    software must display the following acknowledgment:
  18  *    "This product includes software developed by the OpenSSL Project
  19  *    for use in the OpenSSL Toolkit. (http://www.OpenSSL.org/)"
  20  *
  21  * 4. The names "OpenSSL Toolkit" and "OpenSSL Project" must not be used to
  22  *    endorse or promote products derived from this software without
  23  *    prior written permission. For written permission, please contact
  24  *    licensing@OpenSSL.org.
  25  *
  26  * 5. Products derived from this software may not be called "OpenSSL"
  27  *    nor may "OpenSSL" appear in their names without prior written
  28  *    permission of the OpenSSL Project.
  29  *
  30  * 6. Redistributions of any form whatsoever must retain the following
  31  *    acknowledgment:
  32  *    "This product includes software developed by the OpenSSL Project
  33  *    for use in the OpenSSL Toolkit (http://www.OpenSSL.org/)"
  34  *
  35  * THIS SOFTWARE IS PROVIDED BY THE OpenSSL PROJECT ``AS IS'' AND ANY
  36  * EXPRESSED OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
  37  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
  38  * PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL THE OpenSSL PROJECT OR
  39  * ITS CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
  40  * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
  41  * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
  42  * LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
  43  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT,
  44  * STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
  45  * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED
  46  * OF THE POSSIBILITY OF SUCH DAMAGE.
  47  * ====================================================================
  48  */
  49
  50 /* Adapted from the public domain code by D. Bernstein from SUPERCOP. */
  51
  52 #include <string.h>
  53
  54 #include "internal/chacha.h"
  55
  56 typedef unsigned int u32;
  57 typedef unsigned char u8;
  58 typedef union {
  59     u32 u[16];
  60     u8 c[64];
  61 } chacha_buf;
  62
  63 # define ROTATE(v, n) (((v) << (n)) | ((v) >> (32 - (n))))
  64
  65 # define U32TO8_LITTLE(p, v) do { \
  66                                 (p)[0] = (u8)(v >>  0); \
  67                                 (p)[1] = (u8)(v >>  8); \
  68                                 (p)[2] = (u8)(v >> 16); \
  69                                 (p)[3] = (u8)(v >> 24); \
  70                                 } while(0)
  71
  72 /* QUARTERROUND updates a, b, c, d with a ChaCha "quarter" round. */
  73 # define QUARTERROUND(a,b,c,d) ( \
  74                 x[a] += x[b], x[d] = ROTATE((x[d] ^ x[a]),16), \
  75                 x[c] += x[d], x[b] = ROTATE((x[b] ^ x[c]),12), \
  76                 x[a] += x[b], x[d] = ROTATE((x[d] ^ x[a]), 8), \
  77                 x[c] += x[d], x[b] = ROTATE((x[b] ^ x[c]), 7)  )
  78
  79 /* chacha_core performs 20 rounds of ChaCha on the input words in
  80  * |input| and writes the 64 output bytes to |output|. */
  81 static void chacha20_core(chacha_buf *output, const u32 input[16])
  82 {
  83     u32 x[16];
  84     int i;
  85     const union {
  86         long one;
  87         char little;
  88     } is_endian = { 1 };
  89
  90     memcpy(x, input, sizeof(x));
  91
  92     for (i = 20; i > 0; i -= 2) {
  93         QUARTERROUND(0, 4, 8, 12);
  94         QUARTERROUND(1, 5, 9, 13);
  95         QUARTERROUND(2, 6, 10, 14);
  96         QUARTERROUND(3, 7, 11, 15);
  97         QUARTERROUND(0, 5, 10, 15);
  98         QUARTERROUND(1, 6, 11, 12);
  99         QUARTERROUND(2, 7, 8, 13);
 100         QUARTERROUND(3, 4, 9, 14);
 101     }
 102
 103     if (is_endian.little) {
 104         for (i = 0; i < 16; ++i)
 105             output->u[i] = x[i] + input[i];
 106     } else {
 107         for (i = 0; i < 16; ++i)
 108             U32TO8_LITTLE(output->c + 4 * i, (x[i] + input[i]));
 109     }
 110 }
 111
 112 void ChaCha20_ctr32(unsigned char *out, const unsigned char *inp,
 113                     size_t len, const unsigned int key[8],
 114                     const unsigned int counter[4])
 115 {
 116     u32 input[16];
 117     chacha_buf buf;
 118     size_t todo, i;
 119
 120     /* sigma constant "expand 32-byte k" in little-endian encoding */
 121     input[0] = ((u32)'e') | ((u32)'x'<<8) | ((u32)'p'<<16) | ((u32)'a'<<24);
 122     input[1] = ((u32)'n') | ((u32)'d'<<8) | ((u32)' '<<16) | ((u32)'3'<<24);
 123     input[2] = ((u32)'2') | ((u32)'-'<<8) | ((u32)'b'<<16) | ((u32)'y'<<24);
 124     input[3] = ((u32)'t') | ((u32)'e'<<8) | ((u32)' '<<16) | ((u32)'k'<<24);
 125
 126     input[4] = key[0];
 127     input[5] = key[1];
 128     input[6] = key[2];
 129     input[7] = key[3];
 130     input[8] = key[4];
 131     input[9] = key[5];
 132     input[10] = key[6];
 133     input[11] = key[7];
 134
 135     input[12] = counter[0];
 136     input[13] = counter[1];
 137     input[14] = counter[2];
 138     input[15] = counter[3];
 139
 140     while (len > 0) {
 141         todo = sizeof(buf);
 142         if (len < todo)
 143             todo = len;
 144
 145         chacha20_core(&buf, input);
 146
 147         for (i = 0; i < todo; i++)
 148             out[i] = inp[i] ^ buf.c[i];
 149         out += todo;
 150         inp += todo;
 151         len -= todo;
 152
 153         /* advance counter */
 154         if (++input[12] == 0)
 155             input[13]++;
 156     }
 157 }