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 #include <openssl/type_check.h> 50 51 #include <assert.h> 52 #include <string.h> 53 54 #include "internal.h" 55 56 57 /* NOTE: the IV/counter CTR mode is big-endian. The code itself 58 * is endian-neutral. */ 59 60 /* increment counter (128-bit int) by 1 */ 61 static void ctr128_inc(uint8_t *counter) { 62 uint32_t n = 16; 63 uint8_t c; 64 65 do { 66 --n; 67 c = counter[n]; 68 ++c; 69 counter[n] = c; 70 if (c) { 71 return; 72 } 73 } while (n); 74 } 75 76 OPENSSL_COMPILE_ASSERT((16 % sizeof(size_t)) == 0, bad_size_t_size); 77 78 /* The input encrypted as though 128bit counter mode is being used. The extra 79 * state information to record how much of the 128bit block we have used is 80 * contained in *num, and the encrypted counter is kept in ecount_buf. Both 81 * *num and ecount_buf must be initialised with zeros before the first call to 82 * CRYPTO_ctr128_encrypt(). 83 * 84 * This algorithm assumes that the counter is in the x lower bits of the IV 85 * (ivec), and that the application has full control over overflow and the rest 86 * of the IV. This implementation takes NO responsibility for checking that 87 * the counter doesn't overflow into the rest of the IV when incremented. */ 88 void CRYPTO_ctr128_encrypt(const uint8_t *in, uint8_t *out, size_t len, 89 const void *key, uint8_t ivec[16], 90 uint8_t ecount_buf[16], unsigned int *num, 91 block128_f block) { 92 unsigned int n; 93 94 assert(key && ecount_buf && num); 95 assert(len == 0 || (in && out)); 96 assert(*num < 16); 97 98 n = *num; 99 100 while (n && len) { 101 *(out++) = *(in++) ^ ecount_buf[n]; 102 --len; 103 n = (n + 1) % 16; 104 } 105 106 #if STRICT_ALIGNMENT 107 if (((size_t)in | (size_t)out | (size_t)ivec) % sizeof(size_t) != 0) { 108 size_t l = 0; 109 while (l < len) { 110 if (n == 0) { 111 (*block)(ivec, ecount_buf, key); 112 ctr128_inc(ivec); 113 } 114 out[l] = in[l] ^ ecount_buf[n]; 115 ++l; 116 n = (n + 1) % 16; 117 } 118 119 *num = n; 120 return; 121 } 122 #endif 123 124 while (len >= 16) { 125 (*block)(ivec, ecount_buf, key); 126 ctr128_inc(ivec); 127 for (; n < 16; n += sizeof(size_t)) { 128 *(size_t *)(out + n) = *(size_t *)(in + n) ^ *(size_t *)(ecount_buf + n); 129 } 130 len -= 16; 131 out += 16; 132 in += 16; 133 n = 0; 134 } 135 if (len) { 136 (*block)(ivec, ecount_buf, key); 137 ctr128_inc(ivec); 138 while (len--) { 139 out[n] = in[n] ^ ecount_buf[n]; 140 ++n; 141 } 142 } 143 *num = n; 144 } 145 146 /* increment upper 96 bits of 128-bit counter by 1 */ 147 static void ctr96_inc(uint8_t *counter) { 148 uint32_t n = 12; 149 uint8_t c; 150 151 do { 152 --n; 153 c = counter[n]; 154 ++c; 155 counter[n] = c; 156 if (c) { 157 return; 158 } 159 } while (n); 160 } 161 162 void CRYPTO_ctr128_encrypt_ctr32(const uint8_t *in, uint8_t *out, 163 size_t len, const void *key, 164 uint8_t ivec[16], 165 uint8_t ecount_buf[16], 166 unsigned int *num, ctr128_f func) { 167 unsigned int n, ctr32; 168 169 assert(key && ecount_buf && num); 170 assert(len == 0 || (in && out)); 171 assert(*num < 16); 172 173 n = *num; 174 175 while (n && len) { 176 *(out++) = *(in++) ^ ecount_buf[n]; 177 --len; 178 n = (n + 1) % 16; 179 } 180 181 ctr32 = GETU32(ivec + 12); 182 while (len >= 16) { 183 size_t blocks = len / 16; 184 /* 1<<28 is just a not-so-small yet not-so-large number... 185 * Below condition is practically never met, but it has to 186 * be checked for code correctness. */ 187 if (sizeof(size_t) > sizeof(unsigned int) && blocks > (1U << 28)) { 188 blocks = (1U << 28); 189 } 190 /* As (*func) operates on 32-bit counter, caller 191 * has to handle overflow. 'if' below detects the 192 * overflow, which is then handled by limiting the 193 * amount of blocks to the exact overflow point... */ 194 ctr32 += (uint32_t)blocks; 195 if (ctr32 < blocks) { 196 blocks -= ctr32; 197 ctr32 = 0; 198 } 199 (*func)(in, out, blocks, key, ivec); 200 /* (*func) does not update ivec, caller does: */ 201 PUTU32(ivec + 12, ctr32); 202 /* ... overflow was detected, propogate carry. */ 203 if (ctr32 == 0) { 204 ctr96_inc(ivec); 205 } 206 blocks *= 16; 207 len -= blocks; 208 out += blocks; 209 in += blocks; 210 } 211 if (len) { 212 memset(ecount_buf, 0, 16); 213 (*func)(ecount_buf, ecount_buf, 1, key, ivec); 214 ++ctr32; 215 PUTU32(ivec + 12, ctr32); 216 if (ctr32 == 0) { 217 ctr96_inc(ivec); 218 } 219 while (len--) { 220 out[n] = in[n] ^ ecount_buf[n]; 221 ++n; 222 } 223 } 224 225 *num = n; 226 } 227
