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 "xtea.h"
35
36void 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
44static 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#if !CONFIG_SMALL
49    uint32_t k0 = ctx->key[0];
50    uint32_t k1 = ctx->key[1];
51    uint32_t k2 = ctx->key[2];
52    uint32_t k3 = ctx->key[3];
53#endif
54
55    v0 = AV_RB32(src);
56    v1 = AV_RB32(src + 4);
57
58    if (decrypt) {
59#if CONFIG_SMALL
60        int i;
61        uint32_t delta = 0x9E3779B9U, sum = delta * 32;
62
63        for (i = 0; i < 32; i++) {
64            v1 -= (((v0 << 4) ^ (v0 >> 5)) + v0) ^ (sum + ctx->key[(sum >> 11) & 3]);
65            sum -= delta;
66            v0 -= (((v1 << 4) ^ (v1 >> 5)) + v1) ^ (sum + ctx->key[sum & 3]);
67        }
68#else
69#define DSTEP(SUM, K0, K1) \
70            v1 -= (((v0 << 4) ^ (v0 >> 5)) + v0) ^ (SUM + K0); \
71            v0 -= (((v1 << 4) ^ (v1 >> 5)) + v1) ^ (SUM - 0x9E3779B9U + K1)
72
73        DSTEP(0xC6EF3720U, k2, k3);
74        DSTEP(0x28B7BD67U, k3, k2);
75        DSTEP(0x8A8043AEU, k0, k1);
76        DSTEP(0xEC48C9F5U, k1, k0);
77        DSTEP(0x4E11503CU, k2, k3);
78        DSTEP(0xAFD9D683U, k2, k2);
79        DSTEP(0x11A25CCAU, k3, k1);
80        DSTEP(0x736AE311U, k0, k0);
81        DSTEP(0xD5336958U, k1, k3);
82        DSTEP(0x36FBEF9FU, k1, k2);
83        DSTEP(0x98C475E6U, k2, k1);
84        DSTEP(0xFA8CFC2DU, k3, k0);
85        DSTEP(0x5C558274U, k0, k3);
86        DSTEP(0xBE1E08BBU, k1, k2);
87        DSTEP(0x1FE68F02U, k1, k1);
88        DSTEP(0x81AF1549U, k2, k0);
89        DSTEP(0xE3779B90U, k3, k3);
90        DSTEP(0x454021D7U, k0, k2);
91        DSTEP(0xA708A81EU, k1, k1);
92        DSTEP(0x08D12E65U, k1, k0);
93        DSTEP(0x6A99B4ACU, k2, k3);
94        DSTEP(0xCC623AF3U, k3, k2);
95        DSTEP(0x2E2AC13AU, k0, k1);
96        DSTEP(0x8FF34781U, k0, k0);
97        DSTEP(0xF1BBCDC8U, k1, k3);
98        DSTEP(0x5384540FU, k2, k2);
99        DSTEP(0xB54CDA56U, k3, k1);
100        DSTEP(0x1715609DU, k0, k0);
101        DSTEP(0x78DDE6E4U, k0, k3);
102        DSTEP(0xDAA66D2BU, k1, k2);
103        DSTEP(0x3C6EF372U, k2, k1);
104        DSTEP(0x9E3779B9U, k3, k0);
105#endif
106        if (iv) {
107            v0 ^= AV_RB32(iv);
108            v1 ^= AV_RB32(iv + 4);
109            memcpy(iv, src, 8);
110        }
111    } else {
112#if CONFIG_SMALL
113        int i;
114        uint32_t sum = 0, delta = 0x9E3779B9U;
115
116        for (i = 0; i < 32; i++) {
117            v0 += (((v1 << 4) ^ (v1 >> 5)) + v1) ^ (sum + ctx->key[sum & 3]);
118            sum += delta;
119            v1 += (((v0 << 4) ^ (v0 >> 5)) + v0) ^ (sum + ctx->key[(sum >> 11) & 3]);
120        }
121#else
122#define ESTEP(SUM, K0, K1) \
123            v0 += (((v1 << 4) ^ (v1 >> 5)) + v1) ^ (SUM + K0);\
124            v1 += (((v0 << 4) ^ (v0 >> 5)) + v0) ^ (SUM + 0x9E3779B9U + K1)
125        ESTEP(0x00000000U, k0, k3);
126        ESTEP(0x9E3779B9U, k1, k2);
127        ESTEP(0x3C6EF372U, k2, k1);
128        ESTEP(0xDAA66D2BU, k3, k0);
129        ESTEP(0x78DDE6E4U, k0, k0);
130        ESTEP(0x1715609DU, k1, k3);
131        ESTEP(0xB54CDA56U, k2, k2);
132        ESTEP(0x5384540FU, k3, k1);
133        ESTEP(0xF1BBCDC8U, k0, k0);
134        ESTEP(0x8FF34781U, k1, k0);
135        ESTEP(0x2E2AC13AU, k2, k3);
136        ESTEP(0xCC623AF3U, k3, k2);
137        ESTEP(0x6A99B4ACU, k0, k1);
138        ESTEP(0x08D12E65U, k1, k1);
139        ESTEP(0xA708A81EU, k2, k0);
140        ESTEP(0x454021D7U, k3, k3);
141        ESTEP(0xE3779B90U, k0, k2);
142        ESTEP(0x81AF1549U, k1, k1);
143        ESTEP(0x1FE68F02U, k2, k1);
144        ESTEP(0xBE1E08BBU, k3, k0);
145        ESTEP(0x5C558274U, k0, k3);
146        ESTEP(0xFA8CFC2DU, k1, k2);
147        ESTEP(0x98C475E6U, k2, k1);
148        ESTEP(0x36FBEF9FU, k3, k1);
149        ESTEP(0xD5336958U, k0, k0);
150        ESTEP(0x736AE311U, k1, k3);
151        ESTEP(0x11A25CCAU, k2, k2);
152        ESTEP(0xAFD9D683U, k3, k2);
153        ESTEP(0x4E11503CU, k0, k1);
154        ESTEP(0xEC48C9F5U, k1, k0);
155        ESTEP(0x8A8043AEU, k2, k3);
156        ESTEP(0x28B7BD67U, k3, k2);
157#endif
158    }
159
160    AV_WB32(dst, v0);
161    AV_WB32(dst + 4, v1);
162}
163
164void av_xtea_crypt(AVXTEA *ctx, uint8_t *dst, const uint8_t *src, int count,
165                   uint8_t *iv, int decrypt)
166{
167    int i;
168
169    if (decrypt) {
170        while (count--) {
171            xtea_crypt_ecb(ctx, dst, src, decrypt, iv);
172
173            src   += 8;
174            dst   += 8;
175        }
176    } else {
177        while (count--) {
178            if (iv) {
179                for (i = 0; i < 8; i++)
180                    dst[i] = src[i] ^ iv[i];
181                xtea_crypt_ecb(ctx, dst, dst, decrypt, NULL);
182                memcpy(iv, dst, 8);
183            } else {
184                xtea_crypt_ecb(ctx, dst, src, decrypt, NULL);
185            }
186            src   += 8;
187            dst   += 8;
188        }
189    }
190}
191
192#ifdef TEST
193#include <stdio.h>
194
195#define XTEA_NUM_TESTS 6
196
197static const uint8_t xtea_test_key[XTEA_NUM_TESTS][16] = {
198    { 0x00, 0x01, 0x02, 0x03, 0x04, 0x05, 0x06, 0x07,
199      0x08, 0x09, 0x0a, 0x0b, 0x0c, 0x0d, 0x0e, 0x0f },
200    { 0x00, 0x01, 0x02, 0x03, 0x04, 0x05, 0x06, 0x07,
201      0x08, 0x09, 0x0a, 0x0b, 0x0c, 0x0d, 0x0e, 0x0f },
202    { 0x00, 0x01, 0x02, 0x03, 0x04, 0x05, 0x06, 0x07,
203      0x08, 0x09, 0x0a, 0x0b, 0x0c, 0x0d, 0x0e, 0x0f },
204    { 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
205      0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00 },
206    { 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
207      0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00 },
208    { 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
209      0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00 }
210};
211
212static const uint8_t xtea_test_pt[XTEA_NUM_TESTS][8] = {
213    { 0x41, 0x42, 0x43, 0x44, 0x45, 0x46, 0x47, 0x48 },
214    { 0x41, 0x41, 0x41, 0x41, 0x41, 0x41, 0x41, 0x41 },
215    { 0x5a, 0x5b, 0x6e, 0x27, 0x89, 0x48, 0xd7, 0x7f },
216    { 0x41, 0x42, 0x43, 0x44, 0x45, 0x46, 0x47, 0x48 },
217    { 0x41, 0x41, 0x41, 0x41, 0x41, 0x41, 0x41, 0x41 },
218    { 0x70, 0xe1, 0x22, 0x5d, 0x6e, 0x4e, 0x76, 0x55 }
219};
220
221static const uint8_t xtea_test_ct[XTEA_NUM_TESTS][8] = {
222    { 0x49, 0x7d, 0xf3, 0xd0, 0x72, 0x61, 0x2c, 0xb5 },
223    { 0xe7, 0x8f, 0x2d, 0x13, 0x74, 0x43, 0x41, 0xd8 },
224    { 0x41, 0x41, 0x41, 0x41, 0x41, 0x41, 0x41, 0x41 },
225    { 0xa0, 0x39, 0x05, 0x89, 0xf8, 0xb8, 0xef, 0xa5 },
226    { 0xed, 0x23, 0x37, 0x5a, 0x82, 0x1a, 0x8c, 0x2d },
227    { 0x41, 0x41, 0x41, 0x41, 0x41, 0x41, 0x41, 0x41 }
228};
229
230static void test_xtea(AVXTEA *ctx, uint8_t *dst, const uint8_t *src,
231                      const uint8_t *ref, int len, uint8_t *iv, int dir,
232                      const char *test)
233{
234    av_xtea_crypt(ctx, dst, src, len, iv, dir);
235    if (memcmp(dst, ref, 8*len)) {
236        int i;
237        printf("%s failed\ngot      ", test);
238        for (i = 0; i < 8*len; i++)
239            printf("%02x ", dst[i]);
240        printf("\nexpected ");
241        for (i = 0; i < 8*len; i++)
242            printf("%02x ", ref[i]);
243        printf("\n");
244        exit(1);
245    }
246}
247
248int main(void)
249{
250    AVXTEA ctx;
251    uint8_t buf[8], iv[8];
252    int i;
253    static const uint8_t src[32] = "HelloWorldHelloWorldHelloWorld";
254    uint8_t ct[32];
255    uint8_t pl[32];
256
257    for (i = 0; i < XTEA_NUM_TESTS; i++) {
258        av_xtea_init(&ctx, xtea_test_key[i]);
259
260        test_xtea(&ctx, buf, xtea_test_pt[i], xtea_test_ct[i], 1, NULL, 0, "encryption");
261        test_xtea(&ctx, buf, xtea_test_ct[i], xtea_test_pt[i], 1, NULL, 1, "decryption");
262
263        /* encrypt */
264        memcpy(iv, "HALLO123", 8);
265        av_xtea_crypt(&ctx, ct, src, 4, iv, 0);
266
267        /* decrypt into pl */
268        memcpy(iv, "HALLO123", 8);
269        test_xtea(&ctx, pl, ct, src, 4, iv, 1, "CBC decryption");
270
271        memcpy(iv, "HALLO123", 8);
272        test_xtea(&ctx, ct, ct, src, 4, iv, 1, "CBC inplace decryption");
273    }
274
275    printf("Test encryption/decryption success.\n");
276
277    return 0;
278}
279
280#endif
281