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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 "avutil.h"
32#include "common.h"
33#include "intreadwrite.h"
34#include "mem.h"
35#include "xtea.h"
36
37AVXTEA *av_xtea_alloc(void)
38{
39 return av_mallocz(sizeof(struct AVXTEA));
40}
41
42void 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
50void 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
58static 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
178static 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
214static 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
243void 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
249void 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}
254
generated by cgit at 2024-05-17 03:34:02 (GMT)