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 "mem.h"
35 #include "xtea.h"
36 
37 #if !FF_API_CRYPTO_CONTEXT
38 struct AVXTEA {
39  uint32_t key[16];
40 };
41 #endif
42 
44 {
45  return av_mallocz(sizeof(struct AVXTEA));
46 }
47 
48 void av_xtea_init(AVXTEA *ctx, const uint8_t key[16])
49 {
50  int i;
51 
52  for (i = 0; i < 4; i++)
53  ctx->key[i] = AV_RB32(key + (i << 2));
54 }
55 
57 {
58  int i;
59 
60  for (i = 0; i < 4; i++)
61  ctx->key[i] = AV_RL32(key + (i << 2));
62 }
63 
64 static void xtea_crypt_ecb(AVXTEA *ctx, uint8_t *dst, const uint8_t *src,
65  int decrypt, uint8_t *iv)
66 {
67  uint32_t v0, v1;
68  int i;
69 
70  v0 = AV_RB32(src);
71  v1 = AV_RB32(src + 4);
72 
73  if (decrypt) {
74  uint32_t delta = 0x9E3779B9, sum = delta * 32;
75 
76  for (i = 0; i < 32; i++) {
77  v1 -= (((v0 << 4) ^ (v0 >> 5)) + v0) ^ (sum + ctx->key[(sum >> 11) & 3]);
78  sum -= delta;
79  v0 -= (((v1 << 4) ^ (v1 >> 5)) + v1) ^ (sum + ctx->key[sum & 3]);
80  }
81  if (iv) {
82  v0 ^= AV_RB32(iv);
83  v1 ^= AV_RB32(iv + 4);
84  memcpy(iv, src, 8);
85  }
86  } else {
87  uint32_t sum = 0, delta = 0x9E3779B9;
88 
89  for (i = 0; i < 32; i++) {
90  v0 += (((v1 << 4) ^ (v1 >> 5)) + v1) ^ (sum + ctx->key[sum & 3]);
91  sum += delta;
92  v1 += (((v0 << 4) ^ (v0 >> 5)) + v0) ^ (sum + ctx->key[(sum >> 11) & 3]);
93  }
94  }
95 
96  AV_WB32(dst, v0);
97  AV_WB32(dst + 4, v1);
98 }
99 
100 static void xtea_le_crypt_ecb(AVXTEA *ctx, uint8_t *dst, const uint8_t *src,
101  int decrypt, uint8_t *iv)
102 {
103  uint32_t v0, v1;
104  int i;
105 
106  v0 = AV_RL32(src);
107  v1 = AV_RL32(src + 4);
108 
109  if (decrypt) {
110  uint32_t delta = 0x9E3779B9, sum = delta * 32;
111 
112  for (i = 0; i < 32; i++) {
113  v1 -= (((v0 << 4) ^ (v0 >> 5)) + v0) ^ (sum + ctx->key[(sum >> 11) & 3]);
114  sum -= delta;
115  v0 -= (((v1 << 4) ^ (v1 >> 5)) + v1) ^ (sum + ctx->key[sum & 3]);
116  }
117  if (iv) {
118  v0 ^= AV_RL32(iv);
119  v1 ^= AV_RL32(iv + 4);
120  memcpy(iv, src, 8);
121  }
122  } else {
123  uint32_t sum = 0, delta = 0x9E3779B9;
124 
125  for (i = 0; i < 32; i++) {
126  v0 += (((v1 << 4) ^ (v1 >> 5)) + v1) ^ (sum + ctx->key[sum & 3]);
127  sum += delta;
128  v1 += (((v0 << 4) ^ (v0 >> 5)) + v0) ^ (sum + ctx->key[(sum >> 11) & 3]);
129  }
130  }
131 
132  AV_WL32(dst, v0);
133  AV_WL32(dst + 4, v1);
134 }
135 
136 static void xtea_crypt(AVXTEA *ctx, uint8_t *dst, const uint8_t *src, int count,
137  uint8_t *iv, int decrypt,
138  void (*crypt)(AVXTEA *, uint8_t *, const uint8_t *, int, uint8_t *))
139 {
140  int i;
141 
142  if (decrypt) {
143  while (count--) {
144  crypt(ctx, dst, src, decrypt, iv);
145 
146  src += 8;
147  dst += 8;
148  }
149  } else {
150  while (count--) {
151  if (iv) {
152  for (i = 0; i < 8; i++)
153  dst[i] = src[i] ^ iv[i];
154  crypt(ctx, dst, dst, decrypt, NULL);
155  memcpy(iv, dst, 8);
156  } else {
157  crypt(ctx, dst, src, decrypt, NULL);
158  }
159  src += 8;
160  dst += 8;
161  }
162  }
163 }
164 
165 void av_xtea_crypt(AVXTEA *ctx, uint8_t *dst, const uint8_t *src, int count,
166  uint8_t *iv, int decrypt)
167 {
168  xtea_crypt(ctx, dst, src, count, iv, decrypt, xtea_crypt_ecb);
169 }
170 
171 void av_xtea_le_crypt(AVXTEA *ctx, uint8_t *dst, const uint8_t *src, int count,
172  uint8_t *iv, int decrypt)
173 {
174  xtea_crypt(ctx, dst, src, count, iv, decrypt, xtea_le_crypt_ecb);
175 }
memory handling functions
external API header
static const uint8_t crypt[]
Definition: des.c:37
#define AV_WB32(p, val)
Definition: intreadwrite.h:246
uint32_t key[16]
Definition: xtea.h:37
uint8_t
float delta
#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, in big endian format...
Definition: xtea.c:165
#define src
Definition: vp8dsp.c:254
static void xtea_crypt(AVXTEA *ctx, uint8_t *dst, const uint8_t *src, int count, uint8_t *iv, int decrypt, void(*crypt)(AVXTEA *, uint8_t *, const uint8_t *, int, uint8_t *))
Definition: xtea.c:136
static void xtea_crypt_ecb(AVXTEA *ctx, uint8_t *dst, const uint8_t *src, int decrypt, uint8_t *iv)
Definition: xtea.c:64
void av_xtea_init(AVXTEA *ctx, const uint8_t key[16])
Initialize an AVXTEA context.
Definition: xtea.c:48
Public header for libavutil XTEA algorithm.
static void xtea_le_crypt_ecb(AVXTEA *ctx, uint8_t *dst, const uint8_t *src, int decrypt, uint8_t *iv)
Definition: xtea.c:100
AVFormatContext * ctx
Definition: movenc.c:48
#define AV_RL32
Definition: intreadwrite.h:146
NULL
Definition: eval.c:55
void av_xtea_le_init(AVXTEA *ctx, const uint8_t key[16])
Initialize an AVXTEA context.
Definition: xtea.c:56
common internal and external API header
void av_xtea_le_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, in little endian format...
Definition: xtea.c:171
#define AV_WL32(p, val)
Definition: intreadwrite.h:263
Definition: xtea.h:36
AVXTEA * av_xtea_alloc(void)
Allocate an AVXTEA context.
Definition: xtea.c:43
void * av_mallocz(size_t size)
Allocate a block of size bytes with alignment suitable for all memory accesses (including vectors if ...
Definition: mem.c:211