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 (at) 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 /* NOTE: the IV/counter CTR mode is big-endian. The code itself 63 * is endian-neutral. */ 64 65 /* increment counter (128-bit int) by 1 */ 66 static void ctr128_inc(unsigned char *counter) { 67 u32 n=16; 68 u8 c; 69 70 do { 71 --n; 72 c = counter[n]; 73 ++c; 74 counter[n] = c; 75 if (c) return; 76 } while (n); 77 } 78 79 #if !defined(OPENSSL_SMALL_FOOTPRINT) 80 static void ctr128_inc_aligned(unsigned char *counter) { 81 size_t *data,c,n; 82 const union { long one; char little; } is_endian = {1}; 83 84 if (is_endian.little) { 85 ctr128_inc(counter); 86 return; 87 } 88 89 data = (size_t *)counter; 90 n = 16/sizeof(size_t); 91 do { 92 --n; 93 c = data[n]; 94 ++c; 95 data[n] = c; 96 if (c) return; 97 } while (n); 98 } 99 #endif 100 101 /* The input encrypted as though 128bit counter mode is being 102 * used. The extra state information to record how much of the 103 * 128bit block we have used is contained in *num, and the 104 * encrypted counter is kept in ecount_buf. Both *num and 105 * ecount_buf must be initialised with zeros before the first 106 * call to CRYPTO_ctr128_encrypt(). 107 * 108 * This algorithm assumes that the counter is in the x lower bits 109 * of the IV (ivec), and that the application has full control over 110 * overflow and the rest of the IV. This implementation takes NO 111 * responsability for checking that the counter doesn't overflow 112 * into the rest of the IV when incremented. 113 */ 114 void CRYPTO_ctr128_encrypt(const unsigned char *in, unsigned char *out, 115 size_t len, const void *key, 116 unsigned char ivec[16], unsigned char ecount_buf[16], 117 unsigned int *num, block128_f block) 118 { 119 unsigned int n; 120 size_t l=0; 121 122 assert(in && out && key && ecount_buf && num); 123 assert(*num < 16); 124 125 n = *num; 126 127 #if !defined(OPENSSL_SMALL_FOOTPRINT) 128 if (16%sizeof(size_t) == 0) do { /* always true actually */ 129 while (n && len) { 130 *(out++) = *(in++) ^ ecount_buf[n]; 131 --len; 132 n = (n+1) % 16; 133 } 134 135 #if defined(STRICT_ALIGNMENT) 136 if (((size_t)in|(size_t)out|(size_t)ivec)%sizeof(size_t) != 0) 137 break; 138 #endif 139 while (len>=16) { 140 (*block)(ivec, ecount_buf, key); 141 ctr128_inc_aligned(ivec); 142 for (; n<16; n+=sizeof(size_t)) 143 *(size_t *)(out+n) = 144 *(size_t *)(in+n) ^ *(size_t *)(ecount_buf+n); 145 len -= 16; 146 out += 16; 147 in += 16; 148 n = 0; 149 } 150 if (len) { 151 (*block)(ivec, ecount_buf, key); 152 ctr128_inc_aligned(ivec); 153 while (len--) { 154 out[n] = in[n] ^ ecount_buf[n]; 155 ++n; 156 } 157 } 158 *num = n; 159 return; 160 } while(0); 161 /* the rest would be commonly eliminated by x86* compiler */ 162 #endif 163 while (l<len) { 164 if (n==0) { 165 (*block)(ivec, ecount_buf, key); 166 ctr128_inc(ivec); 167 } 168 out[l] = in[l] ^ ecount_buf[n]; 169 ++l; 170 n = (n+1) % 16; 171 } 172 173 *num=n; 174 } 175 176 /* increment upper 96 bits of 128-bit counter by 1 */ 177 static void ctr96_inc(unsigned char *counter) { 178 u32 n=12; 179 u8 c; 180 181 do { 182 --n; 183 c = counter[n]; 184 ++c; 185 counter[n] = c; 186 if (c) return; 187 } while (n); 188 } 189 190 void CRYPTO_ctr128_encrypt_ctr32(const unsigned char *in, unsigned char *out, 191 size_t len, const void *key, 192 unsigned char ivec[16], unsigned char ecount_buf[16], 193 unsigned int *num, ctr128_f func) 194 { 195 unsigned int n,ctr32; 196 197 assert(in && out && key && ecount_buf && num); 198 assert(*num < 16); 199 200 n = *num; 201 202 while (n && len) { 203 *(out++) = *(in++) ^ ecount_buf[n]; 204 --len; 205 n = (n+1) % 16; 206 } 207 208 ctr32 = GETU32(ivec+12); 209 while (len>=16) { 210 size_t blocks = len/16; 211 /* 212 * 1<<28 is just a not-so-small yet not-so-large number... 213 * Below condition is practically never met, but it has to 214 * be checked for code correctness. 215 */ 216 if (sizeof(size_t)>sizeof(unsigned int) && blocks>(1U<<28)) 217 blocks = (1U<<28); 218 /* 219 * As (*func) operates on 32-bit counter, caller 220 * has to handle overflow. 'if' below detects the 221 * overflow, which is then handled by limiting the 222 * amount of blocks to the exact overflow point... 223 */ 224 ctr32 += (u32)blocks; 225 if (ctr32 < blocks) { 226 blocks -= ctr32; 227 ctr32 = 0; 228 } 229 (*func)(in,out,blocks,key,ivec); 230 /* (*ctr) does not update ivec, caller does: */ 231 PUTU32(ivec+12,ctr32); 232 /* ... overflow was detected, propogate carry. */ 233 if (ctr32 == 0) ctr96_inc(ivec); 234 blocks *= 16; 235 len -= blocks; 236 out += blocks; 237 in += blocks; 238 } 239 if (len) { 240 memset(ecount_buf,0,16); 241 (*func)(ecount_buf,ecount_buf,1,key,ivec); 242 ++ctr32; 243 PUTU32(ivec+12,ctr32); 244 if (ctr32 == 0) ctr96_inc(ivec); 245 while (len--) { 246 out[n] = in[n] ^ ecount_buf[n]; 247 ++n; 248 } 249 } 250 251 *num=n; 252 } 253
