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 #include <openssl/modes.h> 49 50 #include <assert.h> 51 52 #include "internal.h" 53 54 55 /* NOTE: the IV/counter CTR mode is big-endian. The code itself 56 * is endian-neutral. */ 57 58 /* increment counter (128-bit int) by 1 */ 59 static void ctr128_inc(uint8_t *counter) { 60 uint32_t n = 16; 61 uint8_t c; 62 63 do { 64 --n; 65 c = counter[n]; 66 ++c; 67 counter[n] = c; 68 if (c) { 69 return; 70 } 71 } while (n); 72 } 73 74 /* The input encrypted as though 128bit counter mode is being used. The extra 75 * state information to record how much of the 128bit block we have used is 76 * contained in *num, and the encrypted counter is kept in ecount_buf. Both 77 * *num and ecount_buf must be initialised with zeros before the first call to 78 * CRYPTO_ctr128_encrypt(). 79 * 80 * This algorithm assumes that the counter is in the x lower bits of the IV 81 * (ivec), and that the application has full control over overflow and the rest 82 * of the IV. This implementation takes NO responsibility for checking that 83 * the counter doesn't overflow into the rest of the IV when incremented. */ 84 void CRYPTO_ctr128_encrypt(const uint8_t *in, uint8_t *out, size_t len, 85 const void *key, uint8_t ivec[16], 86 uint8_t ecount_buf[16], unsigned int *num, 87 block128_f block) { 88 unsigned int n; 89 size_t l=0; 90 91 assert(in && out && key && ecount_buf && num); 92 assert(*num < 16); 93 assert((16 % sizeof(size_t)) == 0); 94 95 n = *num; 96 97 while (n && len) { 98 *(out++) = *(in++) ^ ecount_buf[n]; 99 --len; 100 n = (n + 1) % 16; 101 } 102 103 if (STRICT_ALIGNMENT && 104 ((size_t)in | (size_t)out | (size_t)ivec) % sizeof(size_t) != 0) { 105 while (l < len) { 106 if (n == 0) { 107 (*block)(ivec, ecount_buf, key); 108 ctr128_inc(ivec); 109 } 110 out[l] = in[l] ^ ecount_buf[n]; 111 ++l; 112 n = (n + 1) % 16; 113 } 114 115 *num = n; 116 return; 117 } 118 119 while (len >= 16) { 120 (*block)(ivec, ecount_buf, key); 121 ctr128_inc(ivec); 122 for (; n < 16; n += sizeof(size_t)) 123 *(size_t *)(out + n) = *(size_t *)(in + n) ^ *(size_t *)(ecount_buf + n); 124 len -= 16; 125 out += 16; 126 in += 16; 127 n = 0; 128 } 129 if (len) { 130 (*block)(ivec, ecount_buf, key); 131 ctr128_inc(ivec); 132 while (len--) { 133 out[n] = in[n] ^ ecount_buf[n]; 134 ++n; 135 } 136 } 137 *num = n; 138 } 139 140 /* increment upper 96 bits of 128-bit counter by 1 */ 141 static void ctr96_inc(uint8_t *counter) { 142 uint32_t n = 12; 143 uint8_t c; 144 145 do { 146 --n; 147 c = counter[n]; 148 ++c; 149 counter[n] = c; 150 if (c) { 151 return; 152 } 153 } while (n); 154 } 155 156 void CRYPTO_ctr128_encrypt_ctr32(const uint8_t *in, uint8_t *out, 157 size_t len, const void *key, 158 uint8_t ivec[16], 159 uint8_t ecount_buf[16], 160 unsigned int *num, ctr128_f func) { 161 unsigned int n, ctr32; 162 163 assert(in && out && key && ecount_buf && num); 164 assert(*num < 16); 165 166 n = *num; 167 168 while (n && len) { 169 *(out++) = *(in++) ^ ecount_buf[n]; 170 --len; 171 n = (n + 1) % 16; 172 } 173 174 ctr32 = GETU32(ivec + 12); 175 while (len >= 16) { 176 size_t blocks = len / 16; 177 /* 1<<28 is just a not-so-small yet not-so-large number... 178 * Below condition is practically never met, but it has to 179 * be checked for code correctness. */ 180 if (sizeof(size_t) > sizeof(unsigned int) && blocks > (1U << 28)) 181 blocks = (1U << 28); 182 /* As (*func) operates on 32-bit counter, caller 183 * has to handle overflow. 'if' below detects the 184 * overflow, which is then handled by limiting the 185 * amount of blocks to the exact overflow point... */ 186 ctr32 += (uint32_t)blocks; 187 if (ctr32 < blocks) { 188 blocks -= ctr32; 189 ctr32 = 0; 190 } 191 (*func)(in, out, blocks, key, ivec); 192 /* (*func) does not update ivec, caller does: */ 193 PUTU32(ivec + 12, ctr32); 194 /* ... overflow was detected, propogate carry. */ 195 if (ctr32 == 0) 196 ctr96_inc(ivec); 197 blocks *= 16; 198 len -= blocks; 199 out += blocks; 200 in += blocks; 201 } 202 if (len) { 203 memset(ecount_buf, 0, 16); 204 (*func)(ecount_buf, ecount_buf, 1, key, ivec); 205 ++ctr32; 206 PUTU32(ivec + 12, ctr32); 207 if (ctr32 == 0) { 208 ctr96_inc(ivec); 209 } 210 while (len--) { 211 out[n] = in[n] ^ ecount_buf[n]; 212 ++n; 213 } 214 } 215 216 *num = n; 217 } 218
