FFmpeg
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 /**
25  * @file
26  * @brief XTEA 32-bit implementation
27  * @author Samuel Pitoiset
28  * @ingroup lavu_xtea
29  */
30 
31 #include <string.h>
32 #include "config.h"
33 #include "intreadwrite.h"
34 #include "mem.h"
35 #include "xtea.h"
36 
37 AVXTEA *av_xtea_alloc(void)
38 {
39  return av_mallocz(sizeof(struct AVXTEA));
40 }
41 
42 void av_xtea_init(AVXTEA *ctx, const uint8_t key[16])
43 {
44  int i;
45 
46  for (i = 0; i < 4; i++)
47  ctx->key[i] = AV_RB32(key + (i << 2));
48 }
49 
50 void av_xtea_le_init(AVXTEA *ctx, const uint8_t key[16])
51 {
52  int i;
53 
54  for (i = 0; i < 4; i++)
55  ctx->key[i] = AV_RL32(key + (i << 2));
56 }
57 
58 static void xtea_crypt_ecb(AVXTEA *ctx, uint8_t *dst, const uint8_t *src,
59  int decrypt, uint8_t *iv)
60 {
61  uint32_t v0, v1;
62 #if !CONFIG_SMALL
63  uint32_t k0 = ctx->key[0];
64  uint32_t k1 = ctx->key[1];
65  uint32_t k2 = ctx->key[2];
66  uint32_t k3 = ctx->key[3];
67 #endif
68 
69  v0 = AV_RB32(src);
70  v1 = AV_RB32(src + 4);
71 
72  if (decrypt) {
73 #if CONFIG_SMALL
74  int i;
75  uint32_t delta = 0x9E3779B9U, sum = delta * 32;
76 
77  for (i = 0; i < 32; i++) {
78  v1 -= (((v0 << 4) ^ (v0 >> 5)) + v0) ^ (sum + ctx->key[(sum >> 11) & 3]);
79  sum -= delta;
80  v0 -= (((v1 << 4) ^ (v1 >> 5)) + v1) ^ (sum + ctx->key[sum & 3]);
81  }
82 #else
83 #define DSTEP(SUM, K0, K1) \
84  v1 -= (((v0 << 4) ^ (v0 >> 5)) + v0) ^ (SUM + K0); \
85  v0 -= (((v1 << 4) ^ (v1 >> 5)) + v1) ^ (SUM - 0x9E3779B9U + K1)
86 
87  DSTEP(0xC6EF3720U, k2, k3);
88  DSTEP(0x28B7BD67U, k3, k2);
89  DSTEP(0x8A8043AEU, k0, k1);
90  DSTEP(0xEC48C9F5U, k1, k0);
91  DSTEP(0x4E11503CU, k2, k3);
92  DSTEP(0xAFD9D683U, k2, k2);
93  DSTEP(0x11A25CCAU, k3, k1);
94  DSTEP(0x736AE311U, k0, k0);
95  DSTEP(0xD5336958U, k1, k3);
96  DSTEP(0x36FBEF9FU, k1, k2);
97  DSTEP(0x98C475E6U, k2, k1);
98  DSTEP(0xFA8CFC2DU, k3, k0);
99  DSTEP(0x5C558274U, k0, k3);
100  DSTEP(0xBE1E08BBU, k1, k2);
101  DSTEP(0x1FE68F02U, k1, k1);
102  DSTEP(0x81AF1549U, k2, k0);
103  DSTEP(0xE3779B90U, k3, k3);
104  DSTEP(0x454021D7U, k0, k2);
105  DSTEP(0xA708A81EU, k1, k1);
106  DSTEP(0x08D12E65U, k1, k0);
107  DSTEP(0x6A99B4ACU, k2, k3);
108  DSTEP(0xCC623AF3U, k3, k2);
109  DSTEP(0x2E2AC13AU, k0, k1);
110  DSTEP(0x8FF34781U, k0, k0);
111  DSTEP(0xF1BBCDC8U, k1, k3);
112  DSTEP(0x5384540FU, k2, k2);
113  DSTEP(0xB54CDA56U, k3, k1);
114  DSTEP(0x1715609DU, k0, k0);
115  DSTEP(0x78DDE6E4U, k0, k3);
116  DSTEP(0xDAA66D2BU, k1, k2);
117  DSTEP(0x3C6EF372U, k2, k1);
118  DSTEP(0x9E3779B9U, k3, k0);
119 #endif
120  if (iv) {
121  v0 ^= AV_RB32(iv);
122  v1 ^= AV_RB32(iv + 4);
123  memcpy(iv, src, 8);
124  }
125  } else {
126 #if CONFIG_SMALL
127  int i;
128  uint32_t sum = 0, delta = 0x9E3779B9U;
129 
130  for (i = 0; i < 32; i++) {
131  v0 += (((v1 << 4) ^ (v1 >> 5)) + v1) ^ (sum + ctx->key[sum & 3]);
132  sum += delta;
133  v1 += (((v0 << 4) ^ (v0 >> 5)) + v0) ^ (sum + ctx->key[(sum >> 11) & 3]);
134  }
135 #else
136 #define ESTEP(SUM, K0, K1) \
137  v0 += (((v1 << 4) ^ (v1 >> 5)) + v1) ^ (SUM + K0);\
138  v1 += (((v0 << 4) ^ (v0 >> 5)) + v0) ^ (SUM + 0x9E3779B9U + K1)
139  ESTEP(0x00000000U, k0, k3);
140  ESTEP(0x9E3779B9U, k1, k2);
141  ESTEP(0x3C6EF372U, k2, k1);
142  ESTEP(0xDAA66D2BU, k3, k0);
143  ESTEP(0x78DDE6E4U, k0, k0);
144  ESTEP(0x1715609DU, k1, k3);
145  ESTEP(0xB54CDA56U, k2, k2);
146  ESTEP(0x5384540FU, k3, k1);
147  ESTEP(0xF1BBCDC8U, k0, k0);
148  ESTEP(0x8FF34781U, k1, k0);
149  ESTEP(0x2E2AC13AU, k2, k3);
150  ESTEP(0xCC623AF3U, k3, k2);
151  ESTEP(0x6A99B4ACU, k0, k1);
152  ESTEP(0x08D12E65U, k1, k1);
153  ESTEP(0xA708A81EU, k2, k0);
154  ESTEP(0x454021D7U, k3, k3);
155  ESTEP(0xE3779B90U, k0, k2);
156  ESTEP(0x81AF1549U, k1, k1);
157  ESTEP(0x1FE68F02U, k2, k1);
158  ESTEP(0xBE1E08BBU, k3, k0);
159  ESTEP(0x5C558274U, k0, k3);
160  ESTEP(0xFA8CFC2DU, k1, k2);
161  ESTEP(0x98C475E6U, k2, k1);
162  ESTEP(0x36FBEF9FU, k3, k1);
163  ESTEP(0xD5336958U, k0, k0);
164  ESTEP(0x736AE311U, k1, k3);
165  ESTEP(0x11A25CCAU, k2, k2);
166  ESTEP(0xAFD9D683U, k3, k2);
167  ESTEP(0x4E11503CU, k0, k1);
168  ESTEP(0xEC48C9F5U, k1, k0);
169  ESTEP(0x8A8043AEU, k2, k3);
170  ESTEP(0x28B7BD67U, k3, k2);
171 #endif
172  }
173 
174  AV_WB32(dst, v0);
175  AV_WB32(dst + 4, v1);
176 }
177 
178 static void xtea_le_crypt_ecb(AVXTEA *ctx, uint8_t *dst, const uint8_t *src,
179  int decrypt, uint8_t *iv)
180 {
181  uint32_t v0, v1;
182  int i;
183 
184  v0 = AV_RL32(src);
185  v1 = AV_RL32(src + 4);
186 
187  if (decrypt) {
188  uint32_t delta = 0x9E3779B9, sum = delta * 32;
189 
190  for (i = 0; i < 32; i++) {
191  v1 -= (((v0 << 4) ^ (v0 >> 5)) + v0) ^ (sum + ctx->key[(sum >> 11) & 3]);
192  sum -= delta;
193  v0 -= (((v1 << 4) ^ (v1 >> 5)) + v1) ^ (sum + ctx->key[sum & 3]);
194  }
195  if (iv) {
196  v0 ^= AV_RL32(iv);
197  v1 ^= AV_RL32(iv + 4);
198  memcpy(iv, src, 8);
199  }
200  } else {
201  uint32_t sum = 0, delta = 0x9E3779B9;
202 
203  for (i = 0; i < 32; i++) {
204  v0 += (((v1 << 4) ^ (v1 >> 5)) + v1) ^ (sum + ctx->key[sum & 3]);
205  sum += delta;
206  v1 += (((v0 << 4) ^ (v0 >> 5)) + v0) ^ (sum + ctx->key[(sum >> 11) & 3]);
207  }
208  }
209 
210  AV_WL32(dst, v0);
211  AV_WL32(dst + 4, v1);
212 }
213 
214 static void xtea_crypt(AVXTEA *ctx, uint8_t *dst, const uint8_t *src, int count,
215  uint8_t *iv, int decrypt,
216  void (*crypt)(AVXTEA *, uint8_t *, const uint8_t *, int, uint8_t *))
217 {
218  int i;
219 
220  if (decrypt) {
221  while (count--) {
222  crypt(ctx, dst, src, decrypt, iv);
223 
224  src += 8;
225  dst += 8;
226  }
227  } else {
228  while (count--) {
229  if (iv) {
230  for (i = 0; i < 8; i++)
231  dst[i] = src[i] ^ iv[i];
232  crypt(ctx, dst, dst, decrypt, NULL);
233  memcpy(iv, dst, 8);
234  } else {
235  crypt(ctx, dst, src, decrypt, NULL);
236  }
237  src += 8;
238  dst += 8;
239  }
240  }
241 }
242 
243 void av_xtea_crypt(AVXTEA *ctx, uint8_t *dst, const uint8_t *src, int count,
244  uint8_t *iv, int decrypt)
245 {
246  xtea_crypt(ctx, dst, src, count, iv, decrypt, xtea_crypt_ecb);
247 }
248 
249 void av_xtea_le_crypt(AVXTEA *ctx, uint8_t *dst, const uint8_t *src, int count,
250  uint8_t *iv, int decrypt)
251 {
252  xtea_crypt(ctx, dst, src, count, iv, decrypt, xtea_le_crypt_ecb);
253 }
AV_WL32
#define AV_WL32(p, v)
Definition: intreadwrite.h:422
av_xtea_crypt
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:243
av_xtea_init
void av_xtea_init(AVXTEA *ctx, const uint8_t key[16])
Initialize an AVXTEA context.
Definition: xtea.c:42
xtea_crypt
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:214
xtea_le_crypt_ecb
static void xtea_le_crypt_ecb(AVXTEA *ctx, uint8_t *dst, const uint8_t *src, int decrypt, uint8_t *iv)
Definition: xtea.c:178
intreadwrite.h
ctx
AVFormatContext * ctx
Definition: movenc.c:49
key
const char * key
Definition: hwcontext_opencl.c:189
ESTEP
#define ESTEP(SUM, K0, K1)
NULL
#define NULL
Definition: coverity.c:32
DSTEP
#define DSTEP(SUM, K0, K1)
AV_WB32
#define AV_WB32(p, v)
Definition: intreadwrite.h:415
dst
uint8_t ptrdiff_t const uint8_t ptrdiff_t int intptr_t intptr_t int int16_t * dst
Definition: dsp.h:83
AV_RB32
uint64_t_TMPL AV_WL64 unsigned int_TMPL AV_WL32 unsigned int_TMPL AV_WL24 unsigned int_TMPL AV_WL16 uint64_t_TMPL AV_WB64 unsigned int_TMPL AV_RB32
Definition: bytestream.h:96
av_xtea_le_init
void av_xtea_le_init(AVXTEA *ctx, const uint8_t key[16])
Initialize an AVXTEA context.
Definition: xtea.c:50
i
#define i(width, name, range_min, range_max)
Definition: cbs_h2645.c:256
AVXTEA
Definition: xtea.h:35
delta
float delta
Definition: vorbis_enc_data.h:430
av_mallocz
void * av_mallocz(size_t size)
Allocate a memory block with alignment suitable for all memory accesses (including vectors if availab...
Definition: mem.c:256
av_xtea_alloc
AVXTEA * av_xtea_alloc(void)
Allocate an AVXTEA context.
Definition: xtea.c:37
AV_RL32
uint64_t_TMPL AV_WL64 unsigned int_TMPL AV_RL32
Definition: bytestream.h:92
U
#define U(x)
Definition: vpx_arith.h:37
mem.h
av_xtea_le_crypt
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:249
xtea.h
Public header for libavutil XTEA algorithm.
AVFormatContext::key
const uint8_t * key
Definition: avformat.h:1497
src
#define src
Definition: vp8dsp.c:248
xtea_crypt_ecb
static void xtea_crypt_ecb(AVXTEA *ctx, uint8_t *dst, const uint8_t *src, int decrypt, uint8_t *iv)
Definition: xtea.c:58
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