xtea.c 8.65 KB
Newer Older
1 2 3 4 5 6
/*
 * A 32-bit implementation of the XTEA algorithm
 * Copyright (c) 2012 Samuel Pitoiset
 *
 * loosely based on the implementation of David Wheeler and Roger Needham
 *
7
 * This file is part of FFmpeg.
8
 *
9
 * FFmpeg is free software; you can redistribute it and/or
10 11 12 13
 * modify it under the terms of the GNU Lesser General Public
 * License as published by the Free Software Foundation; either
 * version 2.1 of the License, or (at your option) any later version.
 *
14
 * FFmpeg is distributed in the hope that it will be useful,
15 16 17 18 19
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
 * Lesser General Public License for more details.
 *
 * 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 22 23
 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
 */

24 25 26 27 28 29 30
/**
 * @file
 * @brief XTEA 32-bit implementation
 * @author Samuel Pitoiset
 * @ingroup lavu_xtea
 */

31 32
#include "avutil.h"
#include "common.h"
33
#include "intreadwrite.h"
34 35 36 37 38 39 40 41 42 43 44
#include "xtea.h"

void av_xtea_init(AVXTEA *ctx, const uint8_t key[16])
{
    int i;

    for (i = 0; i < 4; i++)
        ctx->key[i] = AV_RB32(key + (i << 2));
}

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
#if !CONFIG_SMALL
49 50 51 52
    uint32_t k0 = ctx->key[0];
    uint32_t k1 = ctx->key[1];
    uint32_t k2 = ctx->key[2];
    uint32_t k3 = ctx->key[3];
53
#endif
54 55 56 57 58

    v0 = AV_RB32(src);
    v1 = AV_RB32(src + 4);

    if (decrypt) {
59 60
#if CONFIG_SMALL
        int i;
61
        uint32_t delta = 0x9E3779B9U, sum = delta * 32;
62 63 64 65 66 67

        for (i = 0; i < 32; i++) {
            v1 -= (((v0 << 4) ^ (v0 >> 5)) + v0) ^ (sum + ctx->key[(sum >> 11) & 3]);
            sum -= delta;
            v0 -= (((v1 << 4) ^ (v1 >> 5)) + v1) ^ (sum + ctx->key[sum & 3]);
        }
68 69 70
#else
#define DSTEP(SUM, K0, K1) \
            v1 -= (((v0 << 4) ^ (v0 >> 5)) + v0) ^ (SUM + K0); \
71
            v0 -= (((v1 << 4) ^ (v1 >> 5)) + v1) ^ (SUM - 0x9E3779B9U + K1)
72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 100 101 102 103 104

        DSTEP(0xC6EF3720U, k2, k3);
        DSTEP(0x28B7BD67U, k3, k2);
        DSTEP(0x8A8043AEU, k0, k1);
        DSTEP(0xEC48C9F5U, k1, k0);
        DSTEP(0x4E11503CU, k2, k3);
        DSTEP(0xAFD9D683U, k2, k2);
        DSTEP(0x11A25CCAU, k3, k1);
        DSTEP(0x736AE311U, k0, k0);
        DSTEP(0xD5336958U, k1, k3);
        DSTEP(0x36FBEF9FU, k1, k2);
        DSTEP(0x98C475E6U, k2, k1);
        DSTEP(0xFA8CFC2DU, k3, k0);
        DSTEP(0x5C558274U, k0, k3);
        DSTEP(0xBE1E08BBU, k1, k2);
        DSTEP(0x1FE68F02U, k1, k1);
        DSTEP(0x81AF1549U, k2, k0);
        DSTEP(0xE3779B90U, k3, k3);
        DSTEP(0x454021D7U, k0, k2);
        DSTEP(0xA708A81EU, k1, k1);
        DSTEP(0x08D12E65U, k1, k0);
        DSTEP(0x6A99B4ACU, k2, k3);
        DSTEP(0xCC623AF3U, k3, k2);
        DSTEP(0x2E2AC13AU, k0, k1);
        DSTEP(0x8FF34781U, k0, k0);
        DSTEP(0xF1BBCDC8U, k1, k3);
        DSTEP(0x5384540FU, k2, k2);
        DSTEP(0xB54CDA56U, k3, k1);
        DSTEP(0x1715609DU, k0, k0);
        DSTEP(0x78DDE6E4U, k0, k3);
        DSTEP(0xDAA66D2BU, k1, k2);
        DSTEP(0x3C6EF372U, k2, k1);
        DSTEP(0x9E3779B9U, k3, k0);
105 106
#endif
        if (iv) {
107 108
            v0 ^= AV_RB32(iv);
            v1 ^= AV_RB32(iv + 4);
109 110
            memcpy(iv, src, 8);
        }
111
    } else {
112 113
#if CONFIG_SMALL
        int i;
114
        uint32_t sum = 0, delta = 0x9E3779B9U;
115 116 117 118 119 120

        for (i = 0; i < 32; i++) {
            v0 += (((v1 << 4) ^ (v1 >> 5)) + v1) ^ (sum + ctx->key[sum & 3]);
            sum += delta;
            v1 += (((v0 << 4) ^ (v0 >> 5)) + v0) ^ (sum + ctx->key[(sum >> 11) & 3]);
        }
121 122 123
#else
#define ESTEP(SUM, K0, K1) \
            v0 += (((v1 << 4) ^ (v1 >> 5)) + v1) ^ (SUM + K0);\
124
            v1 += (((v0 << 4) ^ (v0 >> 5)) + v0) ^ (SUM + 0x9E3779B9U + K1)
125 126 127 128 129 130 131 132 133 134 135 136 137 138 139 140 141 142 143 144 145 146 147 148 149 150 151 152 153 154 155 156 157
        ESTEP(0x00000000U, k0, k3);
        ESTEP(0x9E3779B9U, k1, k2);
        ESTEP(0x3C6EF372U, k2, k1);
        ESTEP(0xDAA66D2BU, k3, k0);
        ESTEP(0x78DDE6E4U, k0, k0);
        ESTEP(0x1715609DU, k1, k3);
        ESTEP(0xB54CDA56U, k2, k2);
        ESTEP(0x5384540FU, k3, k1);
        ESTEP(0xF1BBCDC8U, k0, k0);
        ESTEP(0x8FF34781U, k1, k0);
        ESTEP(0x2E2AC13AU, k2, k3);
        ESTEP(0xCC623AF3U, k3, k2);
        ESTEP(0x6A99B4ACU, k0, k1);
        ESTEP(0x08D12E65U, k1, k1);
        ESTEP(0xA708A81EU, k2, k0);
        ESTEP(0x454021D7U, k3, k3);
        ESTEP(0xE3779B90U, k0, k2);
        ESTEP(0x81AF1549U, k1, k1);
        ESTEP(0x1FE68F02U, k2, k1);
        ESTEP(0xBE1E08BBU, k3, k0);
        ESTEP(0x5C558274U, k0, k3);
        ESTEP(0xFA8CFC2DU, k1, k2);
        ESTEP(0x98C475E6U, k2, k1);
        ESTEP(0x36FBEF9FU, k3, k1);
        ESTEP(0xD5336958U, k0, k0);
        ESTEP(0x736AE311U, k1, k3);
        ESTEP(0x11A25CCAU, k2, k2);
        ESTEP(0xAFD9D683U, k3, k2);
        ESTEP(0x4E11503CU, k0, k1);
        ESTEP(0xEC48C9F5U, k1, k0);
        ESTEP(0x8A8043AEU, k2, k3);
        ESTEP(0x28B7BD67U, k3, k2);
#endif
158 159 160 161 162 163 164 165 166 167 168
    }

    AV_WB32(dst, v0);
    AV_WB32(dst + 4, v1);
}

void av_xtea_crypt(AVXTEA *ctx, uint8_t *dst, const uint8_t *src, int count,
                   uint8_t *iv, int decrypt)
{
    int i;

169
    if (decrypt) {
170
        while (count--) {
171
            xtea_crypt_ecb(ctx, dst, src, decrypt, iv);
172 173 174 175 176

            src   += 8;
            dst   += 8;
        }
    } else {
177
        while (count--) {
178 179 180
            if (iv) {
                for (i = 0; i < 8; i++)
                    dst[i] = src[i] ^ iv[i];
181
                xtea_crypt_ecb(ctx, dst, dst, decrypt, NULL);
182 183
                memcpy(iv, dst, 8);
            } else {
184
                xtea_crypt_ecb(ctx, dst, src, decrypt, NULL);
185
            }
186 187
            src   += 8;
            dst   += 8;
188 189 190 191 192 193 194 195 196 197 198 199 200 201 202 203 204 205 206 207 208 209 210 211 212 213 214 215 216 217 218 219 220 221 222 223 224 225 226 227 228 229
        }
    }
}

#ifdef TEST
#include <stdio.h>

#define XTEA_NUM_TESTS 6

static const uint8_t xtea_test_key[XTEA_NUM_TESTS][16] = {
    { 0x00, 0x01, 0x02, 0x03, 0x04, 0x05, 0x06, 0x07,
      0x08, 0x09, 0x0a, 0x0b, 0x0c, 0x0d, 0x0e, 0x0f },
    { 0x00, 0x01, 0x02, 0x03, 0x04, 0x05, 0x06, 0x07,
      0x08, 0x09, 0x0a, 0x0b, 0x0c, 0x0d, 0x0e, 0x0f },
    { 0x00, 0x01, 0x02, 0x03, 0x04, 0x05, 0x06, 0x07,
      0x08, 0x09, 0x0a, 0x0b, 0x0c, 0x0d, 0x0e, 0x0f },
    { 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
      0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00 },
    { 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
      0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00 },
    { 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
      0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00 }
};

static const uint8_t xtea_test_pt[XTEA_NUM_TESTS][8] = {
    { 0x41, 0x42, 0x43, 0x44, 0x45, 0x46, 0x47, 0x48 },
    { 0x41, 0x41, 0x41, 0x41, 0x41, 0x41, 0x41, 0x41 },
    { 0x5a, 0x5b, 0x6e, 0x27, 0x89, 0x48, 0xd7, 0x7f },
    { 0x41, 0x42, 0x43, 0x44, 0x45, 0x46, 0x47, 0x48 },
    { 0x41, 0x41, 0x41, 0x41, 0x41, 0x41, 0x41, 0x41 },
    { 0x70, 0xe1, 0x22, 0x5d, 0x6e, 0x4e, 0x76, 0x55 }
};

static const uint8_t xtea_test_ct[XTEA_NUM_TESTS][8] = {
    { 0x49, 0x7d, 0xf3, 0xd0, 0x72, 0x61, 0x2c, 0xb5 },
    { 0xe7, 0x8f, 0x2d, 0x13, 0x74, 0x43, 0x41, 0xd8 },
    { 0x41, 0x41, 0x41, 0x41, 0x41, 0x41, 0x41, 0x41 },
    { 0xa0, 0x39, 0x05, 0x89, 0xf8, 0xb8, 0xef, 0xa5 },
    { 0xed, 0x23, 0x37, 0x5a, 0x82, 0x1a, 0x8c, 0x2d },
    { 0x41, 0x41, 0x41, 0x41, 0x41, 0x41, 0x41, 0x41 }
};

230 231 232 233 234 235 236 237 238 239 240 241 242 243 244 245 246 247
static void test_xtea(AVXTEA *ctx, uint8_t *dst, const uint8_t *src,
                      const uint8_t *ref, int len, uint8_t *iv, int dir,
                      const char *test)
{
    av_xtea_crypt(ctx, dst, src, len, iv, dir);
    if (memcmp(dst, ref, 8*len)) {
        int i;
        printf("%s failed\ngot      ", test);
        for (i = 0; i < 8*len; i++)
            printf("%02x ", dst[i]);
        printf("\nexpected ");
        for (i = 0; i < 8*len; i++)
            printf("%02x ", ref[i]);
        printf("\n");
        exit(1);
    }
}

248 249 250
int main(void)
{
    AVXTEA ctx;
251
    uint8_t buf[8], iv[8];
252
    int i;
253
    static const uint8_t src[32] = "HelloWorldHelloWorldHelloWorld";
254 255
    uint8_t ct[32];
    uint8_t pl[32];
256

257 258 259
    for (i = 0; i < XTEA_NUM_TESTS; i++) {
        av_xtea_init(&ctx, xtea_test_key[i]);

260 261
        test_xtea(&ctx, buf, xtea_test_pt[i], xtea_test_ct[i], 1, NULL, 0, "encryption");
        test_xtea(&ctx, buf, xtea_test_ct[i], xtea_test_pt[i], 1, NULL, 1, "decryption");
262

263 264 265 266 267 268
        /* encrypt */
        memcpy(iv, "HALLO123", 8);
        av_xtea_crypt(&ctx, ct, src, 4, iv, 0);

        /* decrypt into pl */
        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

275 276 277 278 279 280
    printf("Test encryption/decryption success.\n");

    return 0;
}

#endif