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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 #include "libavutil/intreadwrite.h"
25 
26 #include "avutil.h"
27 #include "common.h"
28 #include "xtea.h"
29 
30 void av_xtea_init(AVXTEA *ctx, const uint8_t key[16])
31 {
32  int i;
33 
34  for (i = 0; i < 4; i++)
35  ctx->key[i] = AV_RB32(key + (i << 2));
36 }
37 
38 static void xtea_crypt_ecb(AVXTEA *ctx, uint8_t *dst, const uint8_t *src,
39  int decrypt, uint8_t *iv)
40 {
41  uint32_t v0, v1;
42 #if !CONFIG_SMALL
43  uint32_t k0 = ctx->key[0];
44  uint32_t k1 = ctx->key[1];
45  uint32_t k2 = ctx->key[2];
46  uint32_t k3 = ctx->key[3];
47 #endif
48 
49  v0 = AV_RB32(src);
50  v1 = AV_RB32(src + 4);
51 
52  if (decrypt) {
53 #if CONFIG_SMALL
54  int i;
55  uint32_t delta = 0x9E3779B9U, sum = delta * 32;
56 
57  for (i = 0; i < 32; i++) {
58  v1 -= (((v0 << 4) ^ (v0 >> 5)) + v0) ^ (sum + ctx->key[(sum >> 11) & 3]);
59  sum -= delta;
60  v0 -= (((v1 << 4) ^ (v1 >> 5)) + v1) ^ (sum + ctx->key[sum & 3]);
61  }
62 #else
63 #define DSTEP(SUM, K0, K1) \
64  v1 -= (((v0 << 4) ^ (v0 >> 5)) + v0) ^ (SUM + K0); \
65  v0 -= (((v1 << 4) ^ (v1 >> 5)) + v1) ^ (SUM - 0x9E3779B9U + K1)
66 
67  DSTEP(0xC6EF3720U, k2, k3);
68  DSTEP(0x28B7BD67U, k3, k2);
69  DSTEP(0x8A8043AEU, k0, k1);
70  DSTEP(0xEC48C9F5U, k1, k0);
71  DSTEP(0x4E11503CU, k2, k3);
72  DSTEP(0xAFD9D683U, k2, k2);
73  DSTEP(0x11A25CCAU, k3, k1);
74  DSTEP(0x736AE311U, k0, k0);
75  DSTEP(0xD5336958U, k1, k3);
76  DSTEP(0x36FBEF9FU, k1, k2);
77  DSTEP(0x98C475E6U, k2, k1);
78  DSTEP(0xFA8CFC2DU, k3, k0);
79  DSTEP(0x5C558274U, k0, k3);
80  DSTEP(0xBE1E08BBU, k1, k2);
81  DSTEP(0x1FE68F02U, k1, k1);
82  DSTEP(0x81AF1549U, k2, k0);
83  DSTEP(0xE3779B90U, k3, k3);
84  DSTEP(0x454021D7U, k0, k2);
85  DSTEP(0xA708A81EU, k1, k1);
86  DSTEP(0x08D12E65U, k1, k0);
87  DSTEP(0x6A99B4ACU, k2, k3);
88  DSTEP(0xCC623AF3U, k3, k2);
89  DSTEP(0x2E2AC13AU, k0, k1);
90  DSTEP(0x8FF34781U, k0, k0);
91  DSTEP(0xF1BBCDC8U, k1, k3);
92  DSTEP(0x5384540FU, k2, k2);
93  DSTEP(0xB54CDA56U, k3, k1);
94  DSTEP(0x1715609DU, k0, k0);
95  DSTEP(0x78DDE6E4U, k0, k3);
96  DSTEP(0xDAA66D2BU, k1, k2);
97  DSTEP(0x3C6EF372U, k2, k1);
98  DSTEP(0x9E3779B9U, k3, k0);
99 #endif
100  if (iv) {
101  v0 ^= AV_RB32(iv);
102  v1 ^= AV_RB32(iv + 4);
103  memcpy(iv, src, 8);
104  }
105  } else {
106 #if CONFIG_SMALL
107  int i;
108  uint32_t sum = 0, delta = 0x9E3779B9U;
109 
110  for (i = 0; i < 32; i++) {
111  v0 += (((v1 << 4) ^ (v1 >> 5)) + v1) ^ (sum + ctx->key[sum & 3]);
112  sum += delta;
113  v1 += (((v0 << 4) ^ (v0 >> 5)) + v0) ^ (sum + ctx->key[(sum >> 11) & 3]);
114  }
115 #else
116 #define ESTEP(SUM, K0, K1) \
117  v0 += (((v1 << 4) ^ (v1 >> 5)) + v1) ^ (SUM + K0);\
118  v1 += (((v0 << 4) ^ (v0 >> 5)) + v0) ^ (SUM + 0x9E3779B9U + K1)
119  ESTEP(0x00000000U, k0, k3);
120  ESTEP(0x9E3779B9U, k1, k2);
121  ESTEP(0x3C6EF372U, k2, k1);
122  ESTEP(0xDAA66D2BU, k3, k0);
123  ESTEP(0x78DDE6E4U, k0, k0);
124  ESTEP(0x1715609DU, k1, k3);
125  ESTEP(0xB54CDA56U, k2, k2);
126  ESTEP(0x5384540FU, k3, k1);
127  ESTEP(0xF1BBCDC8U, k0, k0);
128  ESTEP(0x8FF34781U, k1, k0);
129  ESTEP(0x2E2AC13AU, k2, k3);
130  ESTEP(0xCC623AF3U, k3, k2);
131  ESTEP(0x6A99B4ACU, k0, k1);
132  ESTEP(0x08D12E65U, k1, k1);
133  ESTEP(0xA708A81EU, k2, k0);
134  ESTEP(0x454021D7U, k3, k3);
135  ESTEP(0xE3779B90U, k0, k2);
136  ESTEP(0x81AF1549U, k1, k1);
137  ESTEP(0x1FE68F02U, k2, k1);
138  ESTEP(0xBE1E08BBU, k3, k0);
139  ESTEP(0x5C558274U, k0, k3);
140  ESTEP(0xFA8CFC2DU, k1, k2);
141  ESTEP(0x98C475E6U, k2, k1);
142  ESTEP(0x36FBEF9FU, k3, k1);
143  ESTEP(0xD5336958U, k0, k0);
144  ESTEP(0x736AE311U, k1, k3);
145  ESTEP(0x11A25CCAU, k2, k2);
146  ESTEP(0xAFD9D683U, k3, k2);
147  ESTEP(0x4E11503CU, k0, k1);
148  ESTEP(0xEC48C9F5U, k1, k0);
149  ESTEP(0x8A8043AEU, k2, k3);
150  ESTEP(0x28B7BD67U, k3, k2);
151 #endif
152  }
153 
154  AV_WB32(dst, v0);
155  AV_WB32(dst + 4, v1);
156 }
157 
158 void av_xtea_crypt(AVXTEA *ctx, uint8_t *dst, const uint8_t *src, int count,
159  uint8_t *iv, int decrypt)
160 {
161  int i;
162 
163  if (decrypt) {
164  while (count--) {
165  xtea_crypt_ecb(ctx, dst, src, decrypt, iv);
166 
167  src += 8;
168  dst += 8;
169  }
170  } else {
171  while (count--) {
172  if (iv) {
173  for (i = 0; i < 8; i++)
174  dst[i] = src[i] ^ iv[i];
175  xtea_crypt_ecb(ctx, dst, dst, decrypt, NULL);
176  memcpy(iv, dst, 8);
177  } else {
178  xtea_crypt_ecb(ctx, dst, src, decrypt, NULL);
179  }
180  src += 8;
181  dst += 8;
182  }
183  }
184 }
185 
186 #ifdef TEST
187 #include <stdio.h>
188 
189 #define XTEA_NUM_TESTS 6
190 
191 static const uint8_t xtea_test_key[XTEA_NUM_TESTS][16] = {
192  { 0x00, 0x01, 0x02, 0x03, 0x04, 0x05, 0x06, 0x07,
193  0x08, 0x09, 0x0a, 0x0b, 0x0c, 0x0d, 0x0e, 0x0f },
194  { 0x00, 0x01, 0x02, 0x03, 0x04, 0x05, 0x06, 0x07,
195  0x08, 0x09, 0x0a, 0x0b, 0x0c, 0x0d, 0x0e, 0x0f },
196  { 0x00, 0x01, 0x02, 0x03, 0x04, 0x05, 0x06, 0x07,
197  0x08, 0x09, 0x0a, 0x0b, 0x0c, 0x0d, 0x0e, 0x0f },
198  { 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
199  0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00 },
200  { 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
201  0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00 },
202  { 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
203  0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00 }
204 };
205 
206 static const uint8_t xtea_test_pt[XTEA_NUM_TESTS][8] = {
207  { 0x41, 0x42, 0x43, 0x44, 0x45, 0x46, 0x47, 0x48 },
208  { 0x41, 0x41, 0x41, 0x41, 0x41, 0x41, 0x41, 0x41 },
209  { 0x5a, 0x5b, 0x6e, 0x27, 0x89, 0x48, 0xd7, 0x7f },
210  { 0x41, 0x42, 0x43, 0x44, 0x45, 0x46, 0x47, 0x48 },
211  { 0x41, 0x41, 0x41, 0x41, 0x41, 0x41, 0x41, 0x41 },
212  { 0x70, 0xe1, 0x22, 0x5d, 0x6e, 0x4e, 0x76, 0x55 }
213 };
214 
215 static const uint8_t xtea_test_ct[XTEA_NUM_TESTS][8] = {
216  { 0x49, 0x7d, 0xf3, 0xd0, 0x72, 0x61, 0x2c, 0xb5 },
217  { 0xe7, 0x8f, 0x2d, 0x13, 0x74, 0x43, 0x41, 0xd8 },
218  { 0x41, 0x41, 0x41, 0x41, 0x41, 0x41, 0x41, 0x41 },
219  { 0xa0, 0x39, 0x05, 0x89, 0xf8, 0xb8, 0xef, 0xa5 },
220  { 0xed, 0x23, 0x37, 0x5a, 0x82, 0x1a, 0x8c, 0x2d },
221  { 0x41, 0x41, 0x41, 0x41, 0x41, 0x41, 0x41, 0x41 }
222 };
223 
224 static void test_xtea(AVXTEA *ctx, uint8_t *dst, const uint8_t *src,
225  const uint8_t *ref, int len, uint8_t *iv, int dir,
226  const char *test)
227 {
228  av_xtea_crypt(ctx, dst, src, len, iv, dir);
229  if (memcmp(dst, ref, 8*len)) {
230  int i;
231  printf("%s failed\ngot ", test);
232  for (i = 0; i < 8*len; i++)
233  printf("%02x ", dst[i]);
234  printf("\nexpected ");
235  for (i = 0; i < 8*len; i++)
236  printf("%02x ", ref[i]);
237  printf("\n");
238  exit(1);
239  }
240 }
241 
242 int main(void)
243 {
244  AVXTEA ctx;
245  uint8_t buf[8], iv[8];
246  int i;
247  const uint8_t src[32] = "HelloWorldHelloWorldHelloWorld";
248  uint8_t ct[32];
249  uint8_t pl[32];
250 
251  for (i = 0; i < XTEA_NUM_TESTS; i++) {
252  av_xtea_init(&ctx, xtea_test_key[i]);
253 
254  test_xtea(&ctx, buf, xtea_test_pt[i], xtea_test_ct[i], 1, NULL, 0, "encryption");
255  test_xtea(&ctx, buf, xtea_test_ct[i], xtea_test_pt[i], 1, NULL, 1, "decryption");
256 
257  /* encrypt */
258  memcpy(iv, "HALLO123", 8);
259  av_xtea_crypt(&ctx, ct, src, 4, iv, 0);
260 
261  /* decrypt into pl */
262  memcpy(iv, "HALLO123", 8);
263  test_xtea(&ctx, pl, ct, src, 4, iv, 1, "CBC decryption");
264 
265  memcpy(iv, "HALLO123", 8);
266  test_xtea(&ctx, ct, ct, src, 4, iv, 1, "CBC inplace decryption");
267  }
268 
269  printf("Test encryption/decryption success.\n");
270 
271  return 0;
272 }
273 
274 #endif
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