crypto/modes/ofb128.c

   1 /* ====================================================================
   2  * Copyright (c) 2008 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  *    openssl-core@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
  51 #include <openssl/crypto.h>
  52 #include "modes_lcl.h"
  53 #include <string.h>
  54
  55 /*
  56  * The input and output encrypted as though 128bit ofb mode is being used.
  57  * The extra state information to record how much of the 128bit block we have
  58  * used is contained in *num;
  59  */
  60 void CRYPTO_ofb128_encrypt(const unsigned char *in, unsigned char *out,
  61                            size_t len, const void *key,
  62                            unsigned char ivec[16], int *num, block128_f block)
  63 {
  64     unsigned int n;
  65     size_t l = 0;
  66
  67     n = *num;
  68
  69 #if !defined(OPENSSL_SMALL_FOOTPRINT)
  70     if (16 % sizeof(size_t) == 0) { /* always true actually */
  71         do {
  72             while (n && len) {
  73                 *(out++) = *(in++) ^ ivec[n];
  74                 --len;
  75                 n = (n + 1) % 16;
  76             }
  77 # if defined(STRICT_ALIGNMENT)
  78             if (((size_t)in | (size_t)out | (size_t)ivec) % sizeof(size_t) !=
  79                 0)
  80                 break;
  81 # endif
  82             while (len >= 16) {
  83                 (*block) (ivec, ivec, key);
  84                 for (; n < 16; n += sizeof(size_t))
  85                     *(size_t *)(out + n) =
  86                         *(size_t *)(in + n) ^ *(size_t *)(ivec + n);
  87                 len -= 16;
  88                 out += 16;
  89                 in += 16;
  90                 n = 0;
  91             }
  92             if (len) {
  93                 (*block) (ivec, ivec, key);
  94                 while (len--) {
  95                     out[n] = in[n] ^ ivec[n];
  96                     ++n;
  97                 }
  98             }
  99             *num = n;
 100             return;
 101         } while (0);
 102     }
 103     /* the rest would be commonly eliminated by x86* compiler */
 104 #endif
 105     while (l < len) {
 106         if (n == 0) {
 107             (*block) (ivec, ivec, key);
 108         }
 109         out[l] = in[l] ^ ivec[n];
 110         ++l;
 111         n = (n + 1) % 16;
 112     }
 113
 114     *num = n;
 115 }