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 "modes.h" 52 #include <string.h> 53 54 #ifndef MODES_DEBUG 55 # ifndef NDEBUG 56 # define NDEBUG 57 # endif 58 #endif 59 #include <assert.h> 60 61 typedef unsigned int u32; 62 typedef unsigned char u8; 63 64 #define STRICT_ALIGNMENT 65 #if defined(__i386) || defined(__i386__) || \ 66 defined(__x86_64) || defined(__x86_64__) || \ 67 defined(_M_IX86) || defined(_M_AMD64) || defined(_M_X64) || \ 68 defined(__s390__) || defined(__s390x__) 69 # undef STRICT_ALIGNMENT 70 #endif 71 72 /* NOTE: the IV/counter CTR mode is big-endian. The code itself 73 * is endian-neutral. */ 74 75 /* increment counter (128-bit int) by 1 */ 76 static void ctr128_inc(unsigned char *counter) { 77 u32 n=16; 78 u8 c; 79 80 do { 81 --n; 82 c = counter[n]; 83 ++c; 84 counter[n] = c; 85 if (c) return; 86 } while (n); 87 } 88 89 #if !defined(OPENSSL_SMALL_FOOTPRINT) 90 static void ctr128_inc_aligned(unsigned char *counter) { 91 size_t *data,c,n; 92 const union { long one; char little; } is_endian = {1}; 93 94 if (is_endian.little) { 95 ctr128_inc(counter); 96 return; 97 } 98 99 data = (size_t *)counter; 100 n = 16/sizeof(size_t); 101 do { 102 --n; 103 c = data[n]; 104 ++c; 105 data[n] = c; 106 if (c) return; 107 } while (n); 108 } 109 #endif 110 111 /* The input encrypted as though 128bit counter mode is being 112 * used. The extra state information to record how much of the 113 * 128bit block we have used is contained in *num, and the 114 * encrypted counter is kept in ecount_buf. Both *num and 115 * ecount_buf must be initialised with zeros before the first 116 * call to CRYPTO_ctr128_encrypt(). 117 * 118 * This algorithm assumes that the counter is in the x lower bits 119 * of the IV (ivec), and that the application has full control over 120 * overflow and the rest of the IV. This implementation takes NO 121 * responsability for checking that the counter doesn't overflow 122 * into the rest of the IV when incremented. 123 */ 124 void CRYPTO_ctr128_encrypt(const unsigned char *in, unsigned char *out, 125 size_t len, const void *key, 126 unsigned char ivec[16], unsigned char ecount_buf[16], 127 unsigned int *num, block128_f block) 128 { 129 unsigned int n; 130 size_t l=0; 131 132 assert(in && out && key && ecount_buf && num); 133 assert(*num < 16); 134 135 n = *num; 136 137 #if !defined(OPENSSL_SMALL_FOOTPRINT) 138 if (16%sizeof(size_t) == 0) do { /* always true actually */ 139 while (n && len) { 140 *(out++) = *(in++) ^ ecount_buf[n]; 141 --len; 142 n = (n+1) % 16; 143 } 144 145 #if defined(STRICT_ALIGNMENT) 146 if (((size_t)in|(size_t)out|(size_t)ivec)%sizeof(size_t) != 0) 147 break; 148 #endif 149 while (len>=16) { 150 (*block)(ivec, ecount_buf, key); 151 ctr128_inc_aligned(ivec); 152 for (; n<16; n+=sizeof(size_t)) 153 *(size_t *)(out+n) = 154 *(size_t *)(in+n) ^ *(size_t *)(ecount_buf+n); 155 len -= 16; 156 out += 16; 157 in += 16; 158 n = 0; 159 } 160 if (len) { 161 (*block)(ivec, ecount_buf, key); 162 ctr128_inc_aligned(ivec); 163 while (len--) { 164 out[n] = in[n] ^ ecount_buf[n]; 165 ++n; 166 } 167 } 168 *num = n; 169 return; 170 } while(0); 171 /* the rest would be commonly eliminated by x86* compiler */ 172 #endif 173 while (l<len) { 174 if (n==0) { 175 (*block)(ivec, ecount_buf, key); 176 ctr128_inc(ivec); 177 } 178 out[l] = in[l] ^ ecount_buf[n]; 179 ++l; 180 n = (n+1) % 16; 181 } 182 183 *num=n; 184 } 185
