Libav
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 Libav.
8  *
9  * Libav 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  * Libav 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 Libav; 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  int i;
42 
43  v0 = AV_RB32(src);
44  v1 = AV_RB32(src + 4);
45 
46  if (decrypt) {
47  uint32_t delta = 0x9E3779B9, sum = delta * 32;
48 
49  for (i = 0; i < 32; i++) {
50  v1 -= (((v0 << 4) ^ (v0 >> 5)) + v0) ^ (sum + ctx->key[(sum >> 11) & 3]);
51  sum -= delta;
52  v0 -= (((v1 << 4) ^ (v1 >> 5)) + v1) ^ (sum + ctx->key[sum & 3]);
53  }
54  if (iv) {
55  v0 ^= AV_RB32(iv);
56  v1 ^= AV_RB32(iv + 4);
57  memcpy(iv, src, 8);
58  }
59  } else {
60  uint32_t sum = 0, delta = 0x9E3779B9;
61 
62  for (i = 0; i < 32; i++) {
63  v0 += (((v1 << 4) ^ (v1 >> 5)) + v1) ^ (sum + ctx->key[sum & 3]);
64  sum += delta;
65  v1 += (((v0 << 4) ^ (v0 >> 5)) + v0) ^ (sum + ctx->key[(sum >> 11) & 3]);
66  }
67  }
68 
69  AV_WB32(dst, v0);
70  AV_WB32(dst + 4, v1);
71 }
72 
73 void av_xtea_crypt(AVXTEA *ctx, uint8_t *dst, const uint8_t *src, int count,
74  uint8_t *iv, int decrypt)
75 {
76  int i;
77 
78  if (decrypt) {
79  while (count--) {
80  xtea_crypt_ecb(ctx, dst, src, decrypt, iv);
81 
82  src += 8;
83  dst += 8;
84  }
85  } else {
86  while (count--) {
87  if (iv) {
88  for (i = 0; i < 8; i++)
89  dst[i] = src[i] ^ iv[i];
90  xtea_crypt_ecb(ctx, dst, dst, decrypt, NULL);
91  memcpy(iv, dst, 8);
92  } else {
93  xtea_crypt_ecb(ctx, dst, src, decrypt, NULL);
94  }
95  src += 8;
96  dst += 8;
97  }
98  }
99 }
100 
101 #ifdef TEST
102 #include <stdio.h>
103 
104 #define XTEA_NUM_TESTS 6
105 
106 static const uint8_t xtea_test_key[XTEA_NUM_TESTS][16] = {
107  { 0x00, 0x01, 0x02, 0x03, 0x04, 0x05, 0x06, 0x07,
108  0x08, 0x09, 0x0a, 0x0b, 0x0c, 0x0d, 0x0e, 0x0f },
109  { 0x00, 0x01, 0x02, 0x03, 0x04, 0x05, 0x06, 0x07,
110  0x08, 0x09, 0x0a, 0x0b, 0x0c, 0x0d, 0x0e, 0x0f },
111  { 0x00, 0x01, 0x02, 0x03, 0x04, 0x05, 0x06, 0x07,
112  0x08, 0x09, 0x0a, 0x0b, 0x0c, 0x0d, 0x0e, 0x0f },
113  { 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
114  0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00 },
115  { 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
116  0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00 },
117  { 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
118  0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00 }
119 };
120 
121 static const uint8_t xtea_test_pt[XTEA_NUM_TESTS][8] = {
122  { 0x41, 0x42, 0x43, 0x44, 0x45, 0x46, 0x47, 0x48 },
123  { 0x41, 0x41, 0x41, 0x41, 0x41, 0x41, 0x41, 0x41 },
124  { 0x5a, 0x5b, 0x6e, 0x27, 0x89, 0x48, 0xd7, 0x7f },
125  { 0x41, 0x42, 0x43, 0x44, 0x45, 0x46, 0x47, 0x48 },
126  { 0x41, 0x41, 0x41, 0x41, 0x41, 0x41, 0x41, 0x41 },
127  { 0x70, 0xe1, 0x22, 0x5d, 0x6e, 0x4e, 0x76, 0x55 }
128 };
129 
130 static const uint8_t xtea_test_ct[XTEA_NUM_TESTS][8] = {
131  { 0x49, 0x7d, 0xf3, 0xd0, 0x72, 0x61, 0x2c, 0xb5 },
132  { 0xe7, 0x8f, 0x2d, 0x13, 0x74, 0x43, 0x41, 0xd8 },
133  { 0x41, 0x41, 0x41, 0x41, 0x41, 0x41, 0x41, 0x41 },
134  { 0xa0, 0x39, 0x05, 0x89, 0xf8, 0xb8, 0xef, 0xa5 },
135  { 0xed, 0x23, 0x37, 0x5a, 0x82, 0x1a, 0x8c, 0x2d },
136  { 0x41, 0x41, 0x41, 0x41, 0x41, 0x41, 0x41, 0x41 }
137 };
138 
139 static void test_xtea(AVXTEA *ctx, uint8_t *dst, const uint8_t *src,
140  const uint8_t *ref, int len, uint8_t *iv, int dir,
141  const char *test)
142 {
143  av_xtea_crypt(ctx, dst, src, len, iv, dir);
144  if (memcmp(dst, ref, 8*len)) {
145  int i;
146  printf("%s failed\ngot ", test);
147  for (i = 0; i < 8*len; i++)
148  printf("%02x ", dst[i]);
149  printf("\nexpected ");
150  for (i = 0; i < 8*len; i++)
151  printf("%02x ", ref[i]);
152  printf("\n");
153  exit(1);
154  }
155 }
156 
157 int main(void)
158 {
159  AVXTEA ctx;
160  uint8_t buf[8], iv[8];
161  int i;
162  const uint8_t src[32] = "HelloWorldHelloWorldHelloWorld";
163  uint8_t ct[32];
164  uint8_t pl[32];
165 
166  for (i = 0; i < XTEA_NUM_TESTS; i++) {
167  av_xtea_init(&ctx, xtea_test_key[i]);
168 
169  test_xtea(&ctx, buf, xtea_test_pt[i], xtea_test_ct[i], 1, NULL, 0, "encryption");
170  test_xtea(&ctx, buf, xtea_test_ct[i], xtea_test_pt[i], 1, NULL, 1, "decryption");
171 
172  /* encrypt */
173  memcpy(iv, "HALLO123", 8);
174  av_xtea_crypt(&ctx, ct, src, 4, iv, 0);
175 
176  /* decrypt into pl */
177  memcpy(iv, "HALLO123", 8);
178  test_xtea(&ctx, pl, ct, src, 4, iv, 1, "CBC decryption");
179 
180  memcpy(iv, "HALLO123", 8);
181  test_xtea(&ctx, ct, ct, src, 4, iv, 1, "CBC inplace decryption");
182  }
183  printf("Test encryption/decryption success.\n");
184 
185  return 0;
186 }
187 
188 #endif