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| 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 "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 } |
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