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xtea.c
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1 /*
2  * A 32-bit implementation of the XTEA algorithm
3  * Copyright (c) 2012 Samuel Pitoiset
4  *
5  * loosely based on the implementation of David Wheeler and Roger Needham
6  *
7  * This file is part of FFmpeg.
8  *
9  * FFmpeg is free software; you can redistribute it and/or
10  * modify it under the terms of the GNU Lesser General Public
11  * License as published by the Free Software Foundation; either
12  * version 2.1 of the License, or (at your option) any later version.
13  *
14  * FFmpeg is distributed in the hope that it will be useful,
15  * but WITHOUT ANY WARRANTY; without even the implied warranty of
16  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
17  * Lesser General Public License for more details.
18  *
19  * You should have received a copy of the GNU Lesser General Public
20  * License along with FFmpeg; if not, write to the Free Software
21  * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
22  */
23 
24 /**
25  * @file
26  * @brief XTEA 32-bit implementation
27  * @author Samuel Pitoiset
28  * @ingroup lavu_xtea
29  */
30 
31 #include "avutil.h"
32 #include "common.h"
33 #include "intreadwrite.h"
34 #include "xtea.h"
35 
36 void av_xtea_init(AVXTEA *ctx, const uint8_t key[16])
37 {
38  int i;
39 
40  for (i = 0; i < 4; i++)
41  ctx->key[i] = AV_RB32(key + (i << 2));
42 }
43 
44 static void xtea_crypt_ecb(AVXTEA *ctx, uint8_t *dst, const uint8_t *src,
45  int decrypt, uint8_t *iv)
46 {
47  uint32_t v0, v1;
48 #if !CONFIG_SMALL
49  uint32_t k0 = ctx->key[0];
50  uint32_t k1 = ctx->key[1];
51  uint32_t k2 = ctx->key[2];
52  uint32_t k3 = ctx->key[3];
53 #endif
54 
55  v0 = AV_RB32(src);
56  v1 = AV_RB32(src + 4);
57 
58  if (decrypt) {
59 #if CONFIG_SMALL
60  int i;
61  uint32_t delta = 0x9E3779B9U, sum = delta * 32;
62 
63  for (i = 0; i < 32; i++) {
64  v1 -= (((v0 << 4) ^ (v0 >> 5)) + v0) ^ (sum + ctx->key[(sum >> 11) & 3]);
65  sum -= delta;
66  v0 -= (((v1 << 4) ^ (v1 >> 5)) + v1) ^ (sum + ctx->key[sum & 3]);
67  }
68 #else
69 #define DSTEP(SUM, K0, K1) \
70  v1 -= (((v0 << 4) ^ (v0 >> 5)) + v0) ^ (SUM + K0); \
71  v0 -= (((v1 << 4) ^ (v1 >> 5)) + v1) ^ (SUM - 0x9E3779B9U + K1)
72 
73  DSTEP(0xC6EF3720U, k2, k3);
74  DSTEP(0x28B7BD67U, k3, k2);
75  DSTEP(0x8A8043AEU, k0, k1);
76  DSTEP(0xEC48C9F5U, k1, k0);
77  DSTEP(0x4E11503CU, k2, k3);
78  DSTEP(0xAFD9D683U, k2, k2);
79  DSTEP(0x11A25CCAU, k3, k1);
80  DSTEP(0x736AE311U, k0, k0);
81  DSTEP(0xD5336958U, k1, k3);
82  DSTEP(0x36FBEF9FU, k1, k2);
83  DSTEP(0x98C475E6U, k2, k1);
84  DSTEP(0xFA8CFC2DU, k3, k0);
85  DSTEP(0x5C558274U, k0, k3);
86  DSTEP(0xBE1E08BBU, k1, k2);
87  DSTEP(0x1FE68F02U, k1, k1);
88  DSTEP(0x81AF1549U, k2, k0);
89  DSTEP(0xE3779B90U, k3, k3);
90  DSTEP(0x454021D7U, k0, k2);
91  DSTEP(0xA708A81EU, k1, k1);
92  DSTEP(0x08D12E65U, k1, k0);
93  DSTEP(0x6A99B4ACU, k2, k3);
94  DSTEP(0xCC623AF3U, k3, k2);
95  DSTEP(0x2E2AC13AU, k0, k1);
96  DSTEP(0x8FF34781U, k0, k0);
97  DSTEP(0xF1BBCDC8U, k1, k3);
98  DSTEP(0x5384540FU, k2, k2);
99  DSTEP(0xB54CDA56U, k3, k1);
100  DSTEP(0x1715609DU, k0, k0);
101  DSTEP(0x78DDE6E4U, k0, k3);
102  DSTEP(0xDAA66D2BU, k1, k2);
103  DSTEP(0x3C6EF372U, k2, k1);
104  DSTEP(0x9E3779B9U, k3, k0);
105 #endif
106  if (iv) {
107  v0 ^= AV_RB32(iv);
108  v1 ^= AV_RB32(iv + 4);
109  memcpy(iv, src, 8);
110  }
111  } else {
112 #if CONFIG_SMALL
113  int i;
114  uint32_t sum = 0, delta = 0x9E3779B9U;
115 
116  for (i = 0; i < 32; i++) {
117  v0 += (((v1 << 4) ^ (v1 >> 5)) + v1) ^ (sum + ctx->key[sum & 3]);
118  sum += delta;
119  v1 += (((v0 << 4) ^ (v0 >> 5)) + v0) ^ (sum + ctx->key[(sum >> 11) & 3]);
120  }
121 #else
122 #define ESTEP(SUM, K0, K1) \
123  v0 += (((v1 << 4) ^ (v1 >> 5)) + v1) ^ (SUM + K0);\
124  v1 += (((v0 << 4) ^ (v0 >> 5)) + v0) ^ (SUM + 0x9E3779B9U + K1)
125  ESTEP(0x00000000U, k0, k3);
126  ESTEP(0x9E3779B9U, k1, k2);
127  ESTEP(0x3C6EF372U, k2, k1);
128  ESTEP(0xDAA66D2BU, k3, k0);
129  ESTEP(0x78DDE6E4U, k0, k0);
130  ESTEP(0x1715609DU, k1, k3);
131  ESTEP(0xB54CDA56U, k2, k2);
132  ESTEP(0x5384540FU, k3, k1);
133  ESTEP(0xF1BBCDC8U, k0, k0);
134  ESTEP(0x8FF34781U, k1, k0);
135  ESTEP(0x2E2AC13AU, k2, k3);
136  ESTEP(0xCC623AF3U, k3, k2);
137  ESTEP(0x6A99B4ACU, k0, k1);
138  ESTEP(0x08D12E65U, k1, k1);
139  ESTEP(0xA708A81EU, k2, k0);
140  ESTEP(0x454021D7U, k3, k3);
141  ESTEP(0xE3779B90U, k0, k2);
142  ESTEP(0x81AF1549U, k1, k1);
143  ESTEP(0x1FE68F02U, k2, k1);
144  ESTEP(0xBE1E08BBU, k3, k0);
145  ESTEP(0x5C558274U, k0, k3);
146  ESTEP(0xFA8CFC2DU, k1, k2);
147  ESTEP(0x98C475E6U, k2, k1);
148  ESTEP(0x36FBEF9FU, k3, k1);
149  ESTEP(0xD5336958U, k0, k0);
150  ESTEP(0x736AE311U, k1, k3);
151  ESTEP(0x11A25CCAU, k2, k2);
152  ESTEP(0xAFD9D683U, k3, k2);
153  ESTEP(0x4E11503CU, k0, k1);
154  ESTEP(0xEC48C9F5U, k1, k0);
155  ESTEP(0x8A8043AEU, k2, k3);
156  ESTEP(0x28B7BD67U, k3, k2);
157 #endif
158  }
159 
160  AV_WB32(dst, v0);
161  AV_WB32(dst + 4, v1);
162 }
163 
164 void av_xtea_crypt(AVXTEA *ctx, uint8_t *dst, const uint8_t *src, int count,
165  uint8_t *iv, int decrypt)
166 {
167  int i;
168 
169  if (decrypt) {
170  while (count--) {
171  xtea_crypt_ecb(ctx, dst, src, decrypt, iv);
172 
173  src += 8;
174  dst += 8;
175  }
176  } else {
177  while (count--) {
178  if (iv) {
179  for (i = 0; i < 8; i++)
180  dst[i] = src[i] ^ iv[i];
181  xtea_crypt_ecb(ctx, dst, dst, decrypt, NULL);
182  memcpy(iv, dst, 8);
183  } else {
184  xtea_crypt_ecb(ctx, dst, src, decrypt, NULL);
185  }
186  src += 8;
187  dst += 8;
188  }
189  }
190 }
191 
192 #ifdef TEST
193 #include <stdio.h>
194 
195 #define XTEA_NUM_TESTS 6
196 
197 static const uint8_t xtea_test_key[XTEA_NUM_TESTS][16] = {
198  { 0x00, 0x01, 0x02, 0x03, 0x04, 0x05, 0x06, 0x07,
199  0x08, 0x09, 0x0a, 0x0b, 0x0c, 0x0d, 0x0e, 0x0f },
200  { 0x00, 0x01, 0x02, 0x03, 0x04, 0x05, 0x06, 0x07,
201  0x08, 0x09, 0x0a, 0x0b, 0x0c, 0x0d, 0x0e, 0x0f },
202  { 0x00, 0x01, 0x02, 0x03, 0x04, 0x05, 0x06, 0x07,
203  0x08, 0x09, 0x0a, 0x0b, 0x0c, 0x0d, 0x0e, 0x0f },
204  { 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
205  0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00 },
206  { 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
207  0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00 },
208  { 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
209  0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00 }
210 };
211 
212 static const uint8_t xtea_test_pt[XTEA_NUM_TESTS][8] = {
213  { 0x41, 0x42, 0x43, 0x44, 0x45, 0x46, 0x47, 0x48 },
214  { 0x41, 0x41, 0x41, 0x41, 0x41, 0x41, 0x41, 0x41 },
215  { 0x5a, 0x5b, 0x6e, 0x27, 0x89, 0x48, 0xd7, 0x7f },
216  { 0x41, 0x42, 0x43, 0x44, 0x45, 0x46, 0x47, 0x48 },
217  { 0x41, 0x41, 0x41, 0x41, 0x41, 0x41, 0x41, 0x41 },
218  { 0x70, 0xe1, 0x22, 0x5d, 0x6e, 0x4e, 0x76, 0x55 }
219 };
220 
221 static const uint8_t xtea_test_ct[XTEA_NUM_TESTS][8] = {
222  { 0x49, 0x7d, 0xf3, 0xd0, 0x72, 0x61, 0x2c, 0xb5 },
223  { 0xe7, 0x8f, 0x2d, 0x13, 0x74, 0x43, 0x41, 0xd8 },
224  { 0x41, 0x41, 0x41, 0x41, 0x41, 0x41, 0x41, 0x41 },
225  { 0xa0, 0x39, 0x05, 0x89, 0xf8, 0xb8, 0xef, 0xa5 },
226  { 0xed, 0x23, 0x37, 0x5a, 0x82, 0x1a, 0x8c, 0x2d },
227  { 0x41, 0x41, 0x41, 0x41, 0x41, 0x41, 0x41, 0x41 }
228 };
229 
230 static void test_xtea(AVXTEA *ctx, uint8_t *dst, const uint8_t *src,
231  const uint8_t *ref, int len, uint8_t *iv, int dir,
232  const char *test)
233 {
234  av_xtea_crypt(ctx, dst, src, len, iv, dir);
235  if (memcmp(dst, ref, 8*len)) {
236  int i;
237  printf("%s failed\ngot ", test);
238  for (i = 0; i < 8*len; i++)
239  printf("%02x ", dst[i]);
240  printf("\nexpected ");
241  for (i = 0; i < 8*len; i++)
242  printf("%02x ", ref[i]);
243  printf("\n");
244  exit(1);
245  }
246 }
247 
248 int main(void)
249 {
250  AVXTEA ctx;
251  uint8_t buf[8], iv[8];
252  int i;
253  static const uint8_t src[32] = "HelloWorldHelloWorldHelloWorld";
254  uint8_t ct[32];
255  uint8_t pl[32];
256 
257  for (i = 0; i < XTEA_NUM_TESTS; i++) {
258  av_xtea_init(&ctx, xtea_test_key[i]);
259 
260  test_xtea(&ctx, buf, xtea_test_pt[i], xtea_test_ct[i], 1, NULL, 0, "encryption");
261  test_xtea(&ctx, buf, xtea_test_ct[i], xtea_test_pt[i], 1, NULL, 1, "decryption");
262 
263  /* encrypt */
264  memcpy(iv, "HALLO123", 8);
265  av_xtea_crypt(&ctx, ct, src, 4, iv, 0);
266 
267  /* decrypt into pl */
268  memcpy(iv, "HALLO123", 8);
269  test_xtea(&ctx, pl, ct, src, 4, iv, 1, "CBC decryption");
270 
271  memcpy(iv, "HALLO123", 8);
272  test_xtea(&ctx, ct, ct, src, 4, iv, 1, "CBC inplace decryption");
273  }
274 
275  printf("Test encryption/decryption success.\n");
276 
277  return 0;
278 }
279 
280 #endif
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