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#include <openssl/modes.h> 49 50#include <assert.h> 51#include <string.h> 52 53#include "internal.h" 54 55 56/* NOTE: the IV/counter CTR mode is big-endian. The code itself 57 * is endian-neutral. */ 58 59/* increment counter (128-bit int) by 1 */ 60static void ctr128_inc(uint8_t *counter) { 61 uint32_t n = 16; 62 uint8_t c; 63 64 do { 65 --n; 66 c = counter[n]; 67 ++c; 68 counter[n] = c; 69 if (c) { 70 return; 71 } 72 } while (n); 73} 74 75/* The input encrypted as though 128bit counter mode is being used. The extra 76 * state information to record how much of the 128bit block we have used is 77 * contained in *num, and the encrypted counter is kept in ecount_buf. Both 78 * *num and ecount_buf must be initialised with zeros before the first call to 79 * CRYPTO_ctr128_encrypt(). 80 * 81 * This algorithm assumes that the counter is in the x lower bits of the IV 82 * (ivec), and that the application has full control over overflow and the rest 83 * of the IV. This implementation takes NO responsibility for checking that 84 * the counter doesn't overflow into the rest of the IV when incremented. */ 85void CRYPTO_ctr128_encrypt(const uint8_t *in, uint8_t *out, size_t len, 86 const void *key, uint8_t ivec[16], 87 uint8_t ecount_buf[16], unsigned int *num, 88 block128_f block) { 89 unsigned int n; 90 91 assert(key && ecount_buf && num); 92 assert(len == 0 || (in && out)); 93 assert(*num < 16); 94 assert((16 % sizeof(size_t)) == 0); 95 96 n = *num; 97 98 while (n && len) { 99 *(out++) = *(in++) ^ ecount_buf[n]; 100 --len; 101 n = (n + 1) % 16; 102 } 103 104#if STRICT_ALIGNMENT 105 if (((size_t)in | (size_t)out | (size_t)ivec) % sizeof(size_t) != 0) { 106 size_t l = 0; 107 while (l < len) { 108 if (n == 0) { 109 (*block)(ivec, ecount_buf, key); 110 ctr128_inc(ivec); 111 } 112 out[l] = in[l] ^ ecount_buf[n]; 113 ++l; 114 n = (n + 1) % 16; 115 } 116 117 *num = n; 118 return; 119 } 120#endif 121 122 while (len >= 16) { 123 (*block)(ivec, ecount_buf, key); 124 ctr128_inc(ivec); 125 for (; n < 16; n += sizeof(size_t)) { 126 *(size_t *)(out + n) = *(size_t *)(in + n) ^ *(size_t *)(ecount_buf + n); 127 } 128 len -= 16; 129 out += 16; 130 in += 16; 131 n = 0; 132 } 133 if (len) { 134 (*block)(ivec, ecount_buf, key); 135 ctr128_inc(ivec); 136 while (len--) { 137 out[n] = in[n] ^ ecount_buf[n]; 138 ++n; 139 } 140 } 141 *num = n; 142} 143 144/* increment upper 96 bits of 128-bit counter by 1 */ 145static void ctr96_inc(uint8_t *counter) { 146 uint32_t n = 12; 147 uint8_t c; 148 149 do { 150 --n; 151 c = counter[n]; 152 ++c; 153 counter[n] = c; 154 if (c) { 155 return; 156 } 157 } while (n); 158} 159 160void CRYPTO_ctr128_encrypt_ctr32(const uint8_t *in, uint8_t *out, 161 size_t len, const void *key, 162 uint8_t ivec[16], 163 uint8_t ecount_buf[16], 164 unsigned int *num, ctr128_f func) { 165 unsigned int n, ctr32; 166 167 assert(key && ecount_buf && num); 168 assert(len == 0 || (in && out)); 169 assert(*num < 16); 170 171 n = *num; 172 173 while (n && len) { 174 *(out++) = *(in++) ^ ecount_buf[n]; 175 --len; 176 n = (n + 1) % 16; 177 } 178 179 ctr32 = GETU32(ivec + 12); 180 while (len >= 16) { 181 size_t blocks = len / 16; 182 /* 1<<28 is just a not-so-small yet not-so-large number... 183 * Below condition is practically never met, but it has to 184 * be checked for code correctness. */ 185 if (sizeof(size_t) > sizeof(unsigned int) && blocks > (1U << 28)) { 186 blocks = (1U << 28); 187 } 188 /* As (*func) operates on 32-bit counter, caller 189 * has to handle overflow. 'if' below detects the 190 * overflow, which is then handled by limiting the 191 * amount of blocks to the exact overflow point... */ 192 ctr32 += (uint32_t)blocks; 193 if (ctr32 < blocks) { 194 blocks -= ctr32; 195 ctr32 = 0; 196 } 197 (*func)(in, out, blocks, key, ivec); 198 /* (*func) does not update ivec, caller does: */ 199 PUTU32(ivec + 12, ctr32); 200 /* ... overflow was detected, propogate carry. */ 201 if (ctr32 == 0) { 202 ctr96_inc(ivec); 203 } 204 blocks *= 16; 205 len -= blocks; 206 out += blocks; 207 in += blocks; 208 } 209 if (len) { 210 memset(ecount_buf, 0, 16); 211 (*func)(ecount_buf, ecount_buf, 1, key, ivec); 212 ++ctr32; 213 PUTU32(ivec + 12, ctr32); 214 if (ctr32 == 0) { 215 ctr96_inc(ivec); 216 } 217 while (len--) { 218 out[n] = in[n] ^ ecount_buf[n]; 219 ++n; 220 } 221 } 222 223 *num = n; 224} 225