crypto/modes/cfb128.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,
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  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 "modes_lcl.h"
  52 #include <string.h>
  53
  54 #ifndef MODES_DEBUG
  55 # ifndef NDEBUG
  56 #  define NDEBUG
  57 # endif
  58 #endif
  59 #include <assert.h>
  60
  61 /* The input and output encrypted as though 128bit cfb mode is being
  62  * used.  The extra state information to record how much of the
  63  * 128bit block we have used is contained in *num;
  64  */
  65 void CRYPTO_cfb128_encrypt(const unsigned char *in, unsigned char *out,
  66                         size_t len, const void *key,
  67                         unsigned char ivec[16], int *num,
  68                         int enc, block128_f block)
  69 {
  70     unsigned int n;
  71     size_t l = 0;
  72
  73     assert(in && out && key && ivec && num);
  74
  75     n = *num;
  76
  77     if (enc) {
  78 #if !defined(OPENSSL_SMALL_FOOTPRINT)
  79         if (16%sizeof(size_t) == 0) do {        /* always true actually */
  80                 while (n && len) {
  81                         *(out++) = ivec[n] ^= *(in++);
  82                         --len;
  83                         n = (n+1) % 16;
  84                 }
  85 #if defined(STRICT_ALIGNMENT)
  86                 if (((size_t)in|(size_t)out|(size_t)ivec)%sizeof(size_t) != 0)
  87                         break;
  88 #endif
  89                 while (len>=16) {
  90                         (*block)(ivec, ivec, key);
  91                         for (; n<16; n+=sizeof(size_t)) {
  92                                 *(size_t*)(out+n) =
  93                                 *(size_t*)(ivec+n) ^= *(size_t*)(in+n);
  94                         }
  95                         len -= 16;
  96                         out += 16;
  97                         in  += 16;
  98                         n = 0;
  99                 }
 100                 if (len) {
 101                         (*block)(ivec, ivec, key);
 102                         while (len--) {
 103                                 out[n] = ivec[n] ^= in[n];
 104                                 ++n;
 105                         }
 106                 }
 107                 *num = n;
 108                 return;
 109         } while (0);
 110         /* the rest would be commonly eliminated by x86* compiler */
 111 #endif
 112         while (l<len) {
 113                 if (n == 0) {
 114                         (*block)(ivec, ivec, key);
 115                 }
 116                 out[l] = ivec[n] ^= in[l];
 117                 ++l;
 118                 n = (n+1) % 16;
 119         }
 120         *num = n;
 121     } else {
 122 #if !defined(OPENSSL_SMALL_FOOTPRINT)
 123         if (16%sizeof(size_t) == 0) do {        /* always true actually */
 124                 while (n && len) {
 125                         unsigned char c;
 126                         *(out++) = ivec[n] ^ (c = *(in++)); ivec[n] = c;
 127                         --len;
 128                         n = (n+1) % 16;
 129                 }
 130 #if defined(STRICT_ALIGNMENT)
 131                 if (((size_t)in|(size_t)out|(size_t)ivec)%sizeof(size_t) != 0)
 132                         break;
 133 #endif
 134                 while (len>=16) {
 135                         (*block)(ivec, ivec, key);
 136                         for (; n<16; n+=sizeof(size_t)) {
 137                                 size_t t = *(size_t*)(in+n);
 138                                 *(size_t*)(out+n) = *(size_t*)(ivec+n) ^ t;
 139                                 *(size_t*)(ivec+n) = t;
 140                         }
 141                         len -= 16;
 142                         out += 16;
 143                         in  += 16;
 144                         n = 0;
 145                 }
 146                 if (len) {
 147                         (*block)(ivec, ivec, key);
 148                         while (len--) {
 149                                 unsigned char c;
 150                                 out[n] = ivec[n] ^ (c = in[n]); ivec[n] = c;
 151                                 ++n;
 152                         }
 153                 }
 154                 *num = n;
 155                 return;
 156         } while (0);
 157         /* the rest would be commonly eliminated by x86* compiler */
 158 #endif
 159         while (l<len) {
 160                 unsigned char c;
 161                 if (n == 0) {
 162                         (*block)(ivec, ivec, key);
 163                 }
 164                 out[l] = ivec[n] ^ (c = in[l]); ivec[n] = c;
 165                 ++l;
 166                 n = (n+1) % 16;
 167         }
 168         *num=n;
 169     }
 170 }
 171
 172 /* This expects a single block of size nbits for both in and out. Note that
 173    it corrupts any extra bits in the last byte of out */
 174 static void cfbr_encrypt_block(const unsigned char *in,unsigned char *out,
 175                             int nbits,const void *key,
 176                             unsigned char ivec[16],int enc,
 177                             block128_f block)
 178 {
 179     int n,rem,num;
 180     unsigned char ovec[16*2 + 1];  /* +1 because we dererefence (but don't use) one byte off the end */
 181
 182     if (nbits<=0 || nbits>128) return;
 183
 184         /* fill in the first half of the new IV with the current IV */
 185         memcpy(ovec,ivec,16);
 186         /* construct the new IV */
 187         (*block)(ivec,ivec,key);
 188         num = (nbits+7)/8;
 189         if (enc)        /* encrypt the input */
 190             for(n=0 ; n < num ; ++n)
 191                 out[n] = (ovec[16+n] = in[n] ^ ivec[n]);
 192         else            /* decrypt the input */
 193             for(n=0 ; n < num ; ++n)
 194                 out[n] = (ovec[16+n] = in[n]) ^ ivec[n];
 195         /* shift ovec left... */
 196         rem = nbits%8;
 197         num = nbits/8;
 198         if(rem==0)
 199             memcpy(ivec,ovec+num,16);
 200         else
 201             for(n=0 ; n < 16 ; ++n)
 202                 ivec[n] = ovec[n+num]<<rem | ovec[n+num+1]>>(8-rem);
 203
 204     /* it is not necessary to cleanse ovec, since the IV is not secret */
 205 }
 206
 207 /* N.B. This expects the input to be packed, MS bit first */
 208 void CRYPTO_cfb128_1_encrypt(const unsigned char *in, unsigned char *out,
 209                         size_t bits, const void *key,
 210                         unsigned char ivec[16], int *num,
 211                         int enc, block128_f block)
 212 {
 213     size_t n;
 214     unsigned char c[1],d[1];
 215
 216     assert(in && out && key && ivec && num);
 217     assert(*num == 0);
 218
 219     for(n=0 ; n<bits ; ++n)
 220         {
 221         c[0]=(in[n/8]&(1 << (7-n%8))) ? 0x80 : 0;
 222         cfbr_encrypt_block(c,d,1,key,ivec,enc,block);
 223         out[n/8]=(out[n/8]&~(1 << (unsigned int)(7-n%8))) |
 224                  ((d[0]&0x80) >> (unsigned int)(n%8));
 225         }
 226 }
 227
 228 void CRYPTO_cfb128_8_encrypt(const unsigned char *in, unsigned char *out,
 229                         size_t length, const void *key,
 230                         unsigned char ivec[16], int *num,
 231                         int enc, block128_f block)
 232 {
 233     size_t n;
 234
 235     assert(in && out && key && ivec && num);
 236     assert(*num == 0);
 237
 238     for(n=0 ; n<length ; ++n)
 239         cfbr_encrypt_block(&in[n],&out[n],8,key,ivec,enc,block);
 240 }
 241