1 /* $OpenBSD: cfb128.c,v 1.3 2014/06/12 15:49:30 deraadt 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 #include <assert.h> 62 63 /* The input and output encrypted as though 128bit cfb mode is being 64 * used. The extra state information to record how much of the 65 * 128bit block we have used is contained in *num; 66 */ 67 void CRYPTO_cfb128_encrypt(const unsigned char *in, unsigned char *out, 68 size_t len, const void *key, 69 unsigned char ivec[16], int *num, 70 int enc, block128_f block) 71 { 72 unsigned int n; 73 size_t l = 0; 74 75 assert(in && out && key && ivec && num); 76 77 n = *num; 78 79 if (enc) { 80 #if !defined(OPENSSL_SMALL_FOOTPRINT) 81 if (16%sizeof(size_t) == 0) do { /* always true actually */ 82 while (n && len) { 83 *(out++) = ivec[n] ^= *(in++); 84 --len; 85 n = (n+1) % 16; 86 } 87 #ifdef __STRICT_ALIGNMENT 88 if (((size_t)in|(size_t)out|(size_t)ivec)%sizeof(size_t) != 0) 89 break; 90 #endif 91 while (len>=16) { 92 (*block)(ivec, ivec, key); 93 for (; n<16; n+=sizeof(size_t)) { 94 *(size_t*)(out+n) = 95 *(size_t*)(ivec+n) ^= *(size_t*)(in+n); 96 } 97 len -= 16; 98 out += 16; 99 in += 16; 100 n = 0; 101 } 102 if (len) { 103 (*block)(ivec, ivec, key); 104 while (len--) { 105 out[n] = ivec[n] ^= in[n]; 106 ++n; 107 } 108 } 109 *num = n; 110 return; 111 } while (0); 112 /* the rest would be commonly eliminated by x86* compiler */ 113 #endif 114 while (l<len) { 115 if (n == 0) { 116 (*block)(ivec, ivec, key); 117 } 118 out[l] = ivec[n] ^= in[l]; 119 ++l; 120 n = (n+1) % 16; 121 } 122 *num = n; 123 } else { 124 #if !defined(OPENSSL_SMALL_FOOTPRINT) 125 if (16%sizeof(size_t) == 0) do { /* always true actually */ 126 while (n && len) { 127 unsigned char c; 128 *(out++) = ivec[n] ^ (c = *(in++)); ivec[n] = c; 129 --len; 130 n = (n+1) % 16; 131 } 132 #ifdef __STRICT_ALIGNMENT 133 if (((size_t)in|(size_t)out|(size_t)ivec)%sizeof(size_t) != 0) 134 break; 135 #endif 136 while (len>=16) { 137 (*block)(ivec, ivec, key); 138 for (; n<16; n+=sizeof(size_t)) { 139 size_t t = *(size_t*)(in+n); 140 *(size_t*)(out+n) = *(size_t*)(ivec+n) ^ t; 141 *(size_t*)(ivec+n) = t; 142 } 143 len -= 16; 144 out += 16; 145 in += 16; 146 n = 0; 147 } 148 if (len) { 149 (*block)(ivec, ivec, key); 150 while (len--) { 151 unsigned char c; 152 out[n] = ivec[n] ^ (c = in[n]); ivec[n] = c; 153 ++n; 154 } 155 } 156 *num = n; 157 return; 158 } while (0); 159 /* the rest would be commonly eliminated by x86* compiler */ 160 #endif 161 while (l<len) { 162 unsigned char c; 163 if (n == 0) { 164 (*block)(ivec, ivec, key); 165 } 166 out[l] = ivec[n] ^ (c = in[l]); ivec[n] = c; 167 ++l; 168 n = (n+1) % 16; 169 } 170 *num=n; 171 } 172 } 173 174 /* This expects a single block of size nbits for both in and out. Note that 175 it corrupts any extra bits in the last byte of out */ 176 static void cfbr_encrypt_block(const unsigned char *in,unsigned char *out, 177 int nbits,const void *key, 178 unsigned char ivec[16],int enc, 179 block128_f block) 180 { 181 int n,rem,num; 182 unsigned char ovec[16*2 + 1]; /* +1 because we dererefence (but don't use) one byte off the end */ 183 184 if (nbits<=0 || nbits>128) return; 185 186 /* fill in the first half of the new IV with the current IV */ 187 memcpy(ovec,ivec,16); 188 /* construct the new IV */ 189 (*block)(ivec,ivec,key); 190 num = (nbits+7)/8; 191 if (enc) /* encrypt the input */ 192 for(n=0 ; n < num ; ++n) 193 out[n] = (ovec[16+n] = in[n] ^ ivec[n]); 194 else /* decrypt the input */ 195 for(n=0 ; n < num ; ++n) 196 out[n] = (ovec[16+n] = in[n]) ^ ivec[n]; 197 /* shift ovec left... */ 198 rem = nbits%8; 199 num = nbits/8; 200 if(rem==0) 201 memcpy(ivec,ovec+num,16); 202 else 203 for(n=0 ; n < 16 ; ++n) 204 ivec[n] = ovec[n+num]<<rem | ovec[n+num+1]>>(8-rem); 205 206 /* it is not necessary to cleanse ovec, since the IV is not secret */ 207 } 208 209 /* N.B. This expects the input to be packed, MS bit first */ 210 void CRYPTO_cfb128_1_encrypt(const unsigned char *in, unsigned char *out, 211 size_t bits, const void *key, 212 unsigned char ivec[16], int *num, 213 int enc, block128_f block) 214 { 215 size_t n; 216 unsigned char c[1],d[1]; 217 218 assert(in && out && key && ivec && num); 219 assert(*num == 0); 220 221 for(n=0 ; n<bits ; ++n) 222 { 223 c[0]=(in[n/8]&(1 << (7-n%8))) ? 0x80 : 0; 224 cfbr_encrypt_block(c,d,1,key,ivec,enc,block); 225 out[n/8]=(out[n/8]&~(1 << (unsigned int)(7-n%8))) | 226 ((d[0]&0x80) >> (unsigned int)(n%8)); 227 } 228 } 229 230 void CRYPTO_cfb128_8_encrypt(const unsigned char *in, unsigned char *out, 231 size_t length, const void *key, 232 unsigned char ivec[16], int *num, 233 int enc, block128_f block) 234 { 235 size_t n; 236 237 assert(in && out && key && ivec && num); 238 assert(*num == 0); 239 240 for(n=0 ; n<length ; ++n) 241 cfbr_encrypt_block(&in[n],&out[n],8,key,ivec,enc,block); 242 } 243 244