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 * 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/* 63 * NOTE: the IV/counter CTR mode is big-endian. The code itself is 64 * endian-neutral. 65 */ 66 67/* increment counter (128-bit int) by 1 */ 68static void ctr128_inc(unsigned char *counter) 69{ 70 u32 n = 16, c = 1; 71 72 do { 73 --n; 74 c += counter[n]; 75 counter[n] = (u8)c; 76 c >>= 8; 77 } while (n); 78} 79 80#if !defined(OPENSSL_SMALL_FOOTPRINT) 81static void ctr128_inc_aligned(unsigned char *counter) 82{ 83 size_t *data, c, d, n; 84 const union { 85 long one; 86 char little; 87 } is_endian = { 88 1 89 }; 90 91 if (is_endian.little || ((size_t)counter % sizeof(size_t)) != 0) { 92 ctr128_inc(counter); 93 return; 94 } 95 96 data = (size_t *)counter; 97 c = 1; 98 n = 16 / sizeof(size_t); 99 do { 100 --n; 101 d = data[n] += c; 102 /* did addition carry? */ 103 c = ((d - c) ^ d) >> (sizeof(size_t) * 8 - 1); 104 } while (n); 105} 106#endif 107 108/* 109 * The input encrypted as though 128bit counter mode is being used. The 110 * extra state information to record how much of the 128bit block we have 111 * used is contained in *num, and the encrypted counter is kept in 112 * ecount_buf. Both *num and ecount_buf must be initialised with zeros 113 * before the first call to CRYPTO_ctr128_encrypt(). This algorithm assumes 114 * that the counter is in the x lower bits of the IV (ivec), and that the 115 * application has full control over overflow and the rest of the IV. This 116 * implementation takes NO responsability for checking that the counter 117 * doesn't overflow into the rest of the IV when incremented. 118 */ 119void CRYPTO_ctr128_encrypt(const unsigned char *in, unsigned char *out, 120 size_t len, const void *key, 121 unsigned char ivec[16], 122 unsigned char ecount_buf[16], unsigned int *num, 123 block128_f block) 124{ 125 unsigned int n; 126 size_t l = 0; 127 128 assert(in && out && key && ecount_buf && num); 129 assert(*num < 16); 130 131 n = *num; 132 133#if !defined(OPENSSL_SMALL_FOOTPRINT) 134 if (16 % sizeof(size_t) == 0) { /* always true actually */ 135 do { 136 while (n && len) { 137 *(out++) = *(in++) ^ ecount_buf[n]; 138 --len; 139 n = (n + 1) % 16; 140 } 141 142# if defined(STRICT_ALIGNMENT) 143 if (((size_t)in | (size_t)out | (size_t)ecount_buf) 144 % sizeof(size_t) != 0) 145 break; 146# endif 147 while (len >= 16) { 148 (*block) (ivec, ecount_buf, key); 149 ctr128_inc_aligned(ivec); 150 for (n = 0; n < 16; n += sizeof(size_t)) 151 *(size_t *)(out + n) = 152 *(size_t *)(in + n) ^ *(size_t *)(ecount_buf + n); 153 len -= 16; 154 out += 16; 155 in += 16; 156 n = 0; 157 } 158 if (len) { 159 (*block) (ivec, ecount_buf, key); 160 ctr128_inc_aligned(ivec); 161 while (len--) { 162 out[n] = in[n] ^ ecount_buf[n]; 163 ++n; 164 } 165 } 166 *num = n; 167 return; 168 } while (0); 169 } 170 /* the rest would be commonly eliminated by x86* compiler */ 171#endif 172 while (l < len) { 173 if (n == 0) { 174 (*block) (ivec, ecount_buf, key); 175 ctr128_inc(ivec); 176 } 177 out[l] = in[l] ^ ecount_buf[n]; 178 ++l; 179 n = (n + 1) % 16; 180 } 181 182 *num = n; 183} 184 185/* increment upper 96 bits of 128-bit counter by 1 */ 186static void ctr96_inc(unsigned char *counter) 187{ 188 u32 n = 12, c = 1; 189 190 do { 191 --n; 192 c += counter[n]; 193 counter[n] = (u8)c; 194 c >>= 8; 195 } while (n); 196} 197 198void CRYPTO_ctr128_encrypt_ctr32(const unsigned char *in, unsigned char *out, 199 size_t len, const void *key, 200 unsigned char ivec[16], 201 unsigned char ecount_buf[16], 202 unsigned int *num, ctr128_f func) 203{ 204 unsigned int n, ctr32; 205 206 assert(in && out && key && ecount_buf && num); 207 assert(*num < 16); 208 209 n = *num; 210 211 while (n && len) { 212 *(out++) = *(in++) ^ ecount_buf[n]; 213 --len; 214 n = (n + 1) % 16; 215 } 216 217 ctr32 = GETU32(ivec + 12); 218 while (len >= 16) { 219 size_t blocks = len / 16; 220 /* 221 * 1<<28 is just a not-so-small yet not-so-large number... 222 * Below condition is practically never met, but it has to 223 * be checked for code correctness. 224 */ 225 if (sizeof(size_t) > sizeof(unsigned int) && blocks > (1U << 28)) 226 blocks = (1U << 28); 227 /* 228 * As (*func) operates on 32-bit counter, caller 229 * has to handle overflow. 'if' below detects the 230 * overflow, which is then handled by limiting the 231 * amount of blocks to the exact overflow point... 232 */ 233 ctr32 += (u32)blocks; 234 if (ctr32 < blocks) { 235 blocks -= ctr32; 236 ctr32 = 0; 237 } 238 (*func) (in, out, blocks, key, ivec); 239 /* (*ctr) does not update ivec, caller does: */ 240 PUTU32(ivec + 12, ctr32); 241 /* ... overflow was detected, propogate carry. */ 242 if (ctr32 == 0) 243 ctr96_inc(ivec); 244 blocks *= 16; 245 len -= blocks; 246 out += blocks; 247 in += blocks; 248 } 249 if (len) { 250 memset(ecount_buf, 0, 16); 251 (*func) (ecount_buf, ecount_buf, 1, key, ivec); 252 ++ctr32; 253 PUTU32(ivec + 12, ctr32); 254 if (ctr32 == 0) 255 ctr96_inc(ivec); 256 while (len--) { 257 out[n] = in[n] ^ ecount_buf[n]; 258 ++n; 259 } 260 } 261 262 *num = n; 263} 264