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 "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  int i;
43 
44  v0 = AV_RB32(src);
45  v1 = AV_RB32(src + 4);
46 
47  if (decrypt) {
48  uint32_t delta = 0x9E3779B9, sum = delta * 32;
49 
50  for (i = 0; i < 32; i++) {
51  v1 -= (((v0 << 4) ^ (v0 >> 5)) + v0) ^ (sum + ctx->key[(sum >> 11) & 3]);
52  sum -= delta;
53  v0 -= (((v1 << 4) ^ (v1 >> 5)) + v1) ^ (sum + ctx->key[sum & 3]);
54  }
55  if (iv) {
56  v0 ^= AV_RB32(iv);
57  v1 ^= AV_RB32(iv + 4);
58  memcpy(iv, src, 8);
59  }
60  } else {
61  uint32_t sum = 0, delta = 0x9E3779B9;
62 
63  for (i = 0; i < 32; i++) {
64  v0 += (((v1 << 4) ^ (v1 >> 5)) + v1) ^ (sum + ctx->key[sum & 3]);
65  sum += delta;
66  v1 += (((v0 << 4) ^ (v0 >> 5)) + v0) ^ (sum + ctx->key[(sum >> 11) & 3]);
67  }
68  }
69 
70  AV_WB32(dst, v0);
71  AV_WB32(dst + 4, v1);
72 }
73 
74 void av_xtea_crypt(AVXTEA *ctx, uint8_t *dst, const uint8_t *src, int count,
75  uint8_t *iv, int decrypt)
76 {
77  int i;
78 
79  if (decrypt) {
80  while (count--) {
81  xtea_crypt_ecb(ctx, dst, src, decrypt, iv);
82 
83  src += 8;
84  dst += 8;
85  }
86  } else {
87  while (count--) {
88  if (iv) {
89  for (i = 0; i < 8; i++)
90  dst[i] = src[i] ^ iv[i];
91  xtea_crypt_ecb(ctx, dst, dst, decrypt, NULL);
92  memcpy(iv, dst, 8);
93  } else {
94  xtea_crypt_ecb(ctx, dst, src, decrypt, NULL);
95  }
96  src += 8;
97  dst += 8;
98  }
99  }
100 }
101 
102 #ifdef TEST
103 #include <stdio.h>
104 
105 #define XTEA_NUM_TESTS 6
106 
107 static const uint8_t xtea_test_key[XTEA_NUM_TESTS][16] = {
108  { 0x00, 0x01, 0x02, 0x03, 0x04, 0x05, 0x06, 0x07,
109  0x08, 0x09, 0x0a, 0x0b, 0x0c, 0x0d, 0x0e, 0x0f },
110  { 0x00, 0x01, 0x02, 0x03, 0x04, 0x05, 0x06, 0x07,
111  0x08, 0x09, 0x0a, 0x0b, 0x0c, 0x0d, 0x0e, 0x0f },
112  { 0x00, 0x01, 0x02, 0x03, 0x04, 0x05, 0x06, 0x07,
113  0x08, 0x09, 0x0a, 0x0b, 0x0c, 0x0d, 0x0e, 0x0f },
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  0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00 }
120 };
121 
122 static const uint8_t xtea_test_pt[XTEA_NUM_TESTS][8] = {
123  { 0x41, 0x42, 0x43, 0x44, 0x45, 0x46, 0x47, 0x48 },
124  { 0x41, 0x41, 0x41, 0x41, 0x41, 0x41, 0x41, 0x41 },
125  { 0x5a, 0x5b, 0x6e, 0x27, 0x89, 0x48, 0xd7, 0x7f },
126  { 0x41, 0x42, 0x43, 0x44, 0x45, 0x46, 0x47, 0x48 },
127  { 0x41, 0x41, 0x41, 0x41, 0x41, 0x41, 0x41, 0x41 },
128  { 0x70, 0xe1, 0x22, 0x5d, 0x6e, 0x4e, 0x76, 0x55 }
129 };
130 
131 static const uint8_t xtea_test_ct[XTEA_NUM_TESTS][8] = {
132  { 0x49, 0x7d, 0xf3, 0xd0, 0x72, 0x61, 0x2c, 0xb5 },
133  { 0xe7, 0x8f, 0x2d, 0x13, 0x74, 0x43, 0x41, 0xd8 },
134  { 0x41, 0x41, 0x41, 0x41, 0x41, 0x41, 0x41, 0x41 },
135  { 0xa0, 0x39, 0x05, 0x89, 0xf8, 0xb8, 0xef, 0xa5 },
136  { 0xed, 0x23, 0x37, 0x5a, 0x82, 0x1a, 0x8c, 0x2d },
137  { 0x41, 0x41, 0x41, 0x41, 0x41, 0x41, 0x41, 0x41 }
138 };
139 
140 static void test_xtea(AVXTEA *ctx, uint8_t *dst, const uint8_t *src,
141  const uint8_t *ref, int len, uint8_t *iv, int dir,
142  const char *test)
143 {
144  av_xtea_crypt(ctx, dst, src, len, iv, dir);
145  if (memcmp(dst, ref, 8*len)) {
146  int i;
147  printf("%s failed\ngot ", test);
148  for (i = 0; i < 8*len; i++)
149  printf("%02x ", dst[i]);
150  printf("\nexpected ");
151  for (i = 0; i < 8*len; i++)
152  printf("%02x ", ref[i]);
153  printf("\n");
154  exit(1);
155  }
156 }
157 
158 int main(void)
159 {
160  AVXTEA ctx;
161  uint8_t buf[8], iv[8];
162  int i;
163  const uint8_t src[32] = "HelloWorldHelloWorldHelloWorld";
164  uint8_t ct[32];
165  uint8_t pl[32];
166 
167  for (i = 0; i < XTEA_NUM_TESTS; i++) {
168  av_xtea_init(&ctx, xtea_test_key[i]);
169 
170  test_xtea(&ctx, buf, xtea_test_pt[i], xtea_test_ct[i], 1, NULL, 0, "encryption");
171  test_xtea(&ctx, buf, xtea_test_ct[i], xtea_test_pt[i], 1, NULL, 1, "decryption");
172 
173  /* encrypt */
174  memcpy(iv, "HALLO123", 8);
175  av_xtea_crypt(&ctx, ct, src, 4, iv, 0);
176 
177  /* decrypt into pl */
178  memcpy(iv, "HALLO123", 8);
179  test_xtea(&ctx, pl, ct, src, 4, iv, 1, "CBC decryption");
180 
181  memcpy(iv, "HALLO123", 8);
182  test_xtea(&ctx, ct, ct, src, 4, iv, 1, "CBC inplace decryption");
183  }
184  printf("Test encryption/decryption success.\n");
185 
186  return 0;
187 }
188 
189 #endif
external API header
uint32_t key[16]
Definition: xtea.h:33
uint8_t
float delta
#define AV_WB32(p, d)
Definition: intreadwrite.h:239
#define AV_RB32
Definition: intreadwrite.h:130
void av_xtea_crypt(AVXTEA *ctx, uint8_t *dst, const uint8_t *src, int count, uint8_t *iv, int decrypt)
Encrypt or decrypt a buffer using a previously initialized context.
Definition: xtea.c:74
static void xtea_crypt_ecb(AVXTEA *ctx, uint8_t *dst, const uint8_t *src, int decrypt, uint8_t *iv)
Definition: xtea.c:38
int main(int argc, char **argv)
Definition: avconv.c:2348
void av_xtea_init(AVXTEA *ctx, const uint8_t key[16])
Initialize an AVXTEA context.
Definition: xtea.c:30
NULL
Definition: eval.c:52
static void test(const char *base, const char *rel)
Definition: url-test.c:23
#define v0
Definition: regdef.h:26
common internal and external API header
int len
Definition: xtea.h:32