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