lib/libcrypto/modes/cfb128.c

   1 /* $OpenBSD: cfb128.c,v 1.4 2015/02/10 09:46:30 miod Exp $ */
   2 /* ====================================================================
   3  * Copyright (c) 2008 The OpenSSL Project.  All rights reserved.
   4  *
   5  * Redistribution and use in source and binary forms, with or without
   6  * modification, are permitted provided that the following conditions
   7  * are met:
   8  *
   9  * 1. Redistributions of source code must retain the above copyright
  10  *    notice, this list of conditions and the following disclaimer.
  11  *
  12  * 2. Redistributions in binary form must reproduce the above copyright
  13  *    notice, this list of conditions and the following disclaimer in
  14  *    the documentation and/or other materials provided with the
  15  *    distribution.
  16  *
  17  * 3. All advertising materials mentioning features or use of this
  18  *    software must display the following acknowledgment:
  19  *    "This product includes software developed by the OpenSSL Project
  20  *    for use in the OpenSSL Toolkit. (http://www.openssl.org/)"
  21  *
  22  * 4. The names "OpenSSL Toolkit" and "OpenSSL Project" must not be used to
  23  *    endorse or promote products derived from this software without
  24  *    prior written permission. For written permission, please contact
  25  *    openssl-core@openssl.org.
  26  *
  27  * 5. Products derived from this software may not be called "OpenSSL"
  28  *    nor may "OpenSSL" appear in their names without prior written
  29  *    permission of the OpenSSL Project.
  30  *
  31  * 6. Redistributions of any form whatsoever must retain the following
  32  *    acknowledgment:
  33  *    "This product includes software developed by the OpenSSL Project
  34  *    for use in the OpenSSL Toolkit (http://www.openssl.org/)"
  35  *
  36  * THIS SOFTWARE IS PROVIDED BY THE OpenSSL PROJECT ``AS IS'' AND ANY
  37  * EXPRESSED OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
  38  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
  39  * PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL THE OpenSSL PROJECT OR
  40  * ITS CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
  41  * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
  42  * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
  43  * LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
  44  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT,
  45  * STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
  46  * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED
  47  * OF THE POSSIBILITY OF SUCH DAMAGE.
  48  * ====================================================================
  49  *
  50  */
  51
  52 #include <openssl/crypto.h>
  53 #include "modes_lcl.h"
  54 #include <string.h>
  55
  56 #ifndef MODES_DEBUG
  57 # ifndef NDEBUG
  58 #  define NDEBUG
  59 # endif
  60 #endif
  61
  62 /* The input and output encrypted as though 128bit cfb mode is being
  63  * used.  The extra state information to record how much of the
  64  * 128bit block we have used is contained in *num;
  65  */
  66 void CRYPTO_cfb128_encrypt(const unsigned char *in, unsigned char *out,
  67                         size_t len, const void *key,
  68                         unsigned char ivec[16], int *num,
  69                         int enc, block128_f block)
  70 {
  71     unsigned int n;
  72     size_t l = 0;
  73
  74     n = *num;
  75
  76     if (enc) {
  77 #if !defined(OPENSSL_SMALL_FOOTPRINT)
  78         if (16%sizeof(size_t) == 0) do {        /* always true actually */
  79                 while (n && len) {
  80                         *(out++) = ivec[n] ^= *(in++);
  81                         --len;
  82                         n = (n+1) % 16;
  83                 }
  84 #ifdef __STRICT_ALIGNMENT
  85                 if (((size_t)in|(size_t)out|(size_t)ivec)%sizeof(size_t) != 0)
  86                         break;
  87 #endif
  88                 while (len>=16) {
  89                         (*block)(ivec, ivec, key);
  90                         for (; n<16; n+=sizeof(size_t)) {
  91                                 *(size_t*)(out+n) =
  92                                 *(size_t*)(ivec+n) ^= *(size_t*)(in+n);
  93                         }
  94                         len -= 16;
  95                         out += 16;
  96                         in  += 16;
  97                         n = 0;
  98                 }
  99                 if (len) {
 100                         (*block)(ivec, ivec, key);
 101                         while (len--) {
 102                                 out[n] = ivec[n] ^= in[n];
 103                                 ++n;
 104                         }
 105                 }
 106                 *num = n;
 107                 return;
 108         } while (0);
 109         /* the rest would be commonly eliminated by x86* compiler */
 110 #endif
 111         while (l<len) {
 112                 if (n == 0) {
 113                         (*block)(ivec, ivec, key);
 114                 }
 115                 out[l] = ivec[n] ^= in[l];
 116                 ++l;
 117                 n = (n+1) % 16;
 118         }
 119         *num = n;
 120     } else {
 121 #if !defined(OPENSSL_SMALL_FOOTPRINT)
 122         if (16%sizeof(size_t) == 0) do {        /* always true actually */
 123                 while (n && len) {
 124                         unsigned char c;
 125                         *(out++) = ivec[n] ^ (c = *(in++)); ivec[n] = c;
 126                         --len;
 127                         n = (n+1) % 16;
 128                 }
 129 #ifdef __STRICT_ALIGNMENT
 130                 if (((size_t)in|(size_t)out|(size_t)ivec)%sizeof(size_t) != 0)
 131                         break;
 132 #endif
 133                 while (len>=16) {
 134                         (*block)(ivec, ivec, key);
 135                         for (; n<16; n+=sizeof(size_t)) {
 136                                 size_t t = *(size_t*)(in+n);
 137                                 *(size_t*)(out+n) = *(size_t*)(ivec+n) ^ t;
 138                                 *(size_t*)(ivec+n) = t;
 139                         }
 140                         len -= 16;
 141                         out += 16;
 142                         in  += 16;
 143                         n = 0;
 144                 }
 145                 if (len) {
 146                         (*block)(ivec, ivec, key);
 147                         while (len--) {
 148                                 unsigned char c;
 149                                 out[n] = ivec[n] ^ (c = in[n]); ivec[n] = c;
 150                                 ++n;
 151                         }
 152                 }
 153                 *num = n;
 154                 return;
 155         } while (0);
 156         /* the rest would be commonly eliminated by x86* compiler */
 157 #endif
 158         while (l<len) {
 159                 unsigned char c;
 160                 if (n == 0) {
 161                         (*block)(ivec, ivec, key);
 162                 }
 163                 out[l] = ivec[n] ^ (c = in[l]); ivec[n] = c;
 164                 ++l;
 165                 n = (n+1) % 16;
 166         }
 167         *num=n;
 168     }
 169 }
 170
 171 /* This expects a single block of size nbits for both in and out. Note that
 172    it corrupts any extra bits in the last byte of out */
 173 static void cfbr_encrypt_block(const unsigned char *in,unsigned char *out,
 174                             int nbits,const void *key,
 175                             unsigned char ivec[16],int enc,
 176                             block128_f block)
 177 {
 178     int n,rem,num;
 179     unsigned char ovec[16*2 + 1];  /* +1 because we dererefence (but don't use) one byte off the end */
 180
 181     if (nbits<=0 || nbits>128) return;
 182
 183         /* fill in the first half of the new IV with the current IV */
 184         memcpy(ovec,ivec,16);
 185         /* construct the new IV */
 186         (*block)(ivec,ivec,key);
 187         num = (nbits+7)/8;
 188         if (enc)        /* encrypt the input */
 189             for(n=0 ; n < num ; ++n)
 190                 out[n] = (ovec[16+n] = in[n] ^ ivec[n]);
 191         else            /* decrypt the input */
 192             for(n=0 ; n < num ; ++n)
 193                 out[n] = (ovec[16+n] = in[n]) ^ ivec[n];
 194         /* shift ovec left... */
 195         rem = nbits%8;
 196         num = nbits/8;
 197         if(rem==0)
 198             memcpy(ivec,ovec+num,16);
 199         else
 200             for(n=0 ; n < 16 ; ++n)
 201                 ivec[n] = ovec[n+num]<<rem | ovec[n+num+1]>>(8-rem);
 202
 203     /* it is not necessary to cleanse ovec, since the IV is not secret */
 204 }
 205
 206 /* N.B. This expects the input to be packed, MS bit first */
 207 void CRYPTO_cfb128_1_encrypt(const unsigned char *in, unsigned char *out,
 208                         size_t bits, const void *key,
 209                         unsigned char ivec[16], int *num,
 210                         int enc, block128_f block)
 211 {
 212     size_t n;
 213     unsigned char c[1],d[1];
 214
 215     for(n=0 ; n<bits ; ++n)
 216         {
 217         c[0]=(in[n/8]&(1 << (7-n%8))) ? 0x80 : 0;
 218         cfbr_encrypt_block(c,d,1,key,ivec,enc,block);
 219         out[n/8]=(out[n/8]&~(1 << (unsigned int)(7-n%8))) |
 220                  ((d[0]&0x80) >> (unsigned int)(n%8));
 221         }
 222 }
 223
 224 void CRYPTO_cfb128_8_encrypt(const unsigned char *in, unsigned char *out,
 225                         size_t length, const void *key,
 226                         unsigned char ivec[16], int *num,
 227                         int enc, block128_f block)
 228 {
 229     size_t n;
 230
 231     for(n=0 ; n<length ; ++n)
 232         cfbr_encrypt_block(&in[n],&out[n],8,key,ivec,enc,block);
 233 }
 234