crypto/libressl/crypto/chacha/chacha.c

   1 /* $OpenBSD: chacha.c,v 1.6 2014/07/08 14:30:23 bcook Exp $ */
   2 /*
   3  * Copyright (c) 2014 Joel Sing <jsing@openbsd.org>
   4  *
   5  * Permission to use, copy, modify, and distribute this software for any
   6  * purpose with or without fee is hereby granted, provided that the above
   7  * copyright notice and this permission notice appear in all copies.
   8  *
   9  * THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
  10  * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
  11  * MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
  12  * ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
  13  * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
  14  * ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
  15  * OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
  16  */
  17
  18 #include <stdint.h>
  19
  20 #include <openssl/chacha.h>
  21
  22 #include "chacha-merged.c"
  23
  24 void
  25 ChaCha_set_key(ChaCha_ctx *ctx, const unsigned char *key, uint32_t keybits)
  26 {
  27         chacha_keysetup((chacha_ctx *)ctx, key, keybits);
  28         ctx->unused = 0;
  29 }
  30
  31 void
  32 ChaCha_set_iv(ChaCha_ctx *ctx, const unsigned char *iv,
  33     const unsigned char *counter)
  34 {
  35         chacha_ivsetup((chacha_ctx *)ctx, iv, counter);
  36         ctx->unused = 0;
  37 }
  38
  39 void
  40 ChaCha(ChaCha_ctx *ctx, unsigned char *out, const unsigned char *in, size_t len)
  41 {
  42         unsigned char *k;
  43         int i, l;
  44
  45         /* Consume remaining keystream, if any exists. */
  46         if (ctx->unused > 0) {
  47                 k = ctx->ks + 64 - ctx->unused;
  48                 l = (len > ctx->unused) ? ctx->unused : len;
  49                 for (i = 0; i < l; i++)
  50                         *(out++) = *(in++) ^ *(k++);
  51                 ctx->unused -= l;
  52                 len -= l;
  53         }
  54
  55         chacha_encrypt_bytes((chacha_ctx *)ctx, in, out, (uint32_t)len);
  56 }
  57
  58 void
  59 CRYPTO_chacha_20(unsigned char *out, const unsigned char *in, size_t len,
  60     const unsigned char key[32], const unsigned char iv[8], uint64_t counter)
  61 {
  62         struct chacha_ctx ctx;
  63
  64         /*
  65          * chacha_ivsetup expects the counter to be in u8. Rather than
  66          * converting size_t to u8 and then back again, pass a counter of
  67          * NULL and manually assign it afterwards.
  68          */
  69         chacha_keysetup(&ctx, key, 256);
  70         chacha_ivsetup(&ctx, iv, NULL);
  71         if (counter != 0) {
  72                 ctx.input[12] = (uint32_t)counter;
  73                 ctx.input[13] = (uint32_t)(counter >> 32);
  74         }
  75
  76         chacha_encrypt_bytes(&ctx, in, out, (uint32_t)len);
  77 }