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