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 
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  int i;
49 
50  v0 = AV_RB32(src);
51  v1 = AV_RB32(src + 4);
52 
53  if (decrypt) {
54  uint32_t delta = 0x9E3779B9, 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  if (iv) {
62  v0 ^= AV_RB32(iv);
63  v1 ^= AV_RB32(iv + 4);
64  memcpy(iv, src, 8);
65  }
66  } else {
67  uint32_t sum = 0, delta = 0x9E3779B9;
68 
69  for (i = 0; i < 32; i++) {
70  v0 += (((v1 << 4) ^ (v1 >> 5)) + v1) ^ (sum + ctx->key[sum & 3]);
71  sum += delta;
72  v1 += (((v0 << 4) ^ (v0 >> 5)) + v0) ^ (sum + ctx->key[(sum >> 11) & 3]);
73  }
74  }
75 
76  AV_WB32(dst, v0);
77  AV_WB32(dst + 4, v1);
78 }
79 
80 void av_xtea_crypt(AVXTEA *ctx, uint8_t *dst, const uint8_t *src, int count,
81  uint8_t *iv, int decrypt)
82 {
83  int i;
84 
85  if (decrypt) {
86  while (count--) {
87  xtea_crypt_ecb(ctx, dst, src, decrypt, iv);
88 
89  src += 8;
90  dst += 8;
91  }
92  } else {
93  while (count--) {
94  if (iv) {
95  for (i = 0; i < 8; i++)
96  dst[i] = src[i] ^ iv[i];
97  xtea_crypt_ecb(ctx, dst, dst, decrypt, NULL);
98  memcpy(iv, dst, 8);
99  } else {
100  xtea_crypt_ecb(ctx, dst, src, decrypt, NULL);
101  }
102  src += 8;
103  dst += 8;
104  }
105  }
106 }
107 
108 #ifdef TEST
109 #include <stdio.h>
110 
111 #define XTEA_NUM_TESTS 6
112 
113 static const uint8_t xtea_test_key[XTEA_NUM_TESTS][16] = {
114  { 0x00, 0x01, 0x02, 0x03, 0x04, 0x05, 0x06, 0x07,
115  0x08, 0x09, 0x0a, 0x0b, 0x0c, 0x0d, 0x0e, 0x0f },
116  { 0x00, 0x01, 0x02, 0x03, 0x04, 0x05, 0x06, 0x07,
117  0x08, 0x09, 0x0a, 0x0b, 0x0c, 0x0d, 0x0e, 0x0f },
118  { 0x00, 0x01, 0x02, 0x03, 0x04, 0x05, 0x06, 0x07,
119  0x08, 0x09, 0x0a, 0x0b, 0x0c, 0x0d, 0x0e, 0x0f },
120  { 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
121  0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00 },
122  { 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
123  0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00 },
124  { 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
125  0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00 }
126 };
127 
128 static const uint8_t xtea_test_pt[XTEA_NUM_TESTS][8] = {
129  { 0x41, 0x42, 0x43, 0x44, 0x45, 0x46, 0x47, 0x48 },
130  { 0x41, 0x41, 0x41, 0x41, 0x41, 0x41, 0x41, 0x41 },
131  { 0x5a, 0x5b, 0x6e, 0x27, 0x89, 0x48, 0xd7, 0x7f },
132  { 0x41, 0x42, 0x43, 0x44, 0x45, 0x46, 0x47, 0x48 },
133  { 0x41, 0x41, 0x41, 0x41, 0x41, 0x41, 0x41, 0x41 },
134  { 0x70, 0xe1, 0x22, 0x5d, 0x6e, 0x4e, 0x76, 0x55 }
135 };
136 
137 static const uint8_t xtea_test_ct[XTEA_NUM_TESTS][8] = {
138  { 0x49, 0x7d, 0xf3, 0xd0, 0x72, 0x61, 0x2c, 0xb5 },
139  { 0xe7, 0x8f, 0x2d, 0x13, 0x74, 0x43, 0x41, 0xd8 },
140  { 0x41, 0x41, 0x41, 0x41, 0x41, 0x41, 0x41, 0x41 },
141  { 0xa0, 0x39, 0x05, 0x89, 0xf8, 0xb8, 0xef, 0xa5 },
142  { 0xed, 0x23, 0x37, 0x5a, 0x82, 0x1a, 0x8c, 0x2d },
143  { 0x41, 0x41, 0x41, 0x41, 0x41, 0x41, 0x41, 0x41 }
144 };
145 
146 static void test_xtea(AVXTEA *ctx, uint8_t *dst, const uint8_t *src,
147  const uint8_t *ref, int len, uint8_t *iv, int dir,
148  const char *test)
149 {
150  av_xtea_crypt(ctx, dst, src, len, iv, dir);
151  if (memcmp(dst, ref, 8*len)) {
152  int i;
153  printf("%s failed\ngot ", test);
154  for (i = 0; i < 8*len; i++)
155  printf("%02x ", dst[i]);
156  printf("\nexpected ");
157  for (i = 0; i < 8*len; i++)
158  printf("%02x ", ref[i]);
159  printf("\n");
160  exit(1);
161  }
162 }
163 
164 int main(void)
165 {
166  AVXTEA ctx;
167  uint8_t buf[8], iv[8];
168  int i;
169  const uint8_t src[32] = "HelloWorldHelloWorldHelloWorld";
170  uint8_t ct[32];
171  uint8_t pl[32];
172 
173  for (i = 0; i < XTEA_NUM_TESTS; i++) {
174  av_xtea_init(&ctx, xtea_test_key[i]);
175 
176  test_xtea(&ctx, buf, xtea_test_pt[i], xtea_test_ct[i], 1, NULL, 0, "encryption");
177  test_xtea(&ctx, buf, xtea_test_ct[i], xtea_test_pt[i], 1, NULL, 1, "decryption");
178 
179  /* encrypt */
180  memcpy(iv, "HALLO123", 8);
181  av_xtea_crypt(&ctx, ct, src, 4, iv, 0);
182 
183  /* decrypt into pl */
184  memcpy(iv, "HALLO123", 8);
185  test_xtea(&ctx, pl, ct, src, 4, iv, 1, "CBC decryption");
186 
187  memcpy(iv, "HALLO123", 8);
188  test_xtea(&ctx, ct, ct, src, 4, iv, 1, "CBC inplace decryption");
189  }
190  printf("Test encryption/decryption success.\n");
191 
192  return 0;
193 }
194 
195 #endif
uint32_t key[16]
Definition: xtea.h:35
uint8_t
float delta
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:80
#define AV_WB32(p, d)
Definition: intreadwrite.h:239
static void xtea_crypt_ecb(AVXTEA *ctx, uint8_t *dst, const uint8_t *src, int decrypt, uint8_t *iv)
Definition: xtea.c:44
int main(int argc, char **argv)
Definition: avconv.c:2608
void av_xtea_init(AVXTEA *ctx, const uint8_t key[16])
Initialize an AVXTEA context.
Definition: xtea.c:36
Public header for libavutil XTEA algorithm.
static void test(const char *pattern, const char *host)
Definition: noproxy-test.c:23
NULL
Definition: eval.c:55
external API header
#define AV_RB32(x)
Definition: intreadwrite.h:232
int len
common internal and external API header
Definition: xtea.h:34