FFmpeg: libavutil/xtea.c Source File

00001 /*
00002  * A 32-bit implementation of the XTEA algorithm
00003  * Copyright (c) 2012 Samuel Pitoiset
00004  *
00005  * loosely based on the implementation of David Wheeler and Roger Needham
00006  *
00007  * This file is part of FFmpeg.
00008  *
00009  * FFmpeg is free software; you can redistribute it and/or
00010  * modify it under the terms of the GNU Lesser General Public
00011  * License as published by the Free Software Foundation; either
00012  * version 2.1 of the License, or (at your option) any later version.
00013  *
00014  * FFmpeg is distributed in the hope that it will be useful,
00015  * but WITHOUT ANY WARRANTY; without even the implied warranty of
00016  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
00017  * Lesser General Public License for more details.
00018  *
00019  * You should have received a copy of the GNU Lesser General Public
00020  * License along with FFmpeg; if not, write to the Free Software
00021  * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
00022  */
00023 
00024 #include "libavutil/intreadwrite.h"
00025 
00026 #include "avutil.h"
00027 #include "common.h"
00028 #include "xtea.h"
00029 
00030 void av_xtea_init(AVXTEA *ctx, const uint8_t key[16])
00031 {
00032     int i;
00033 
00034     for (i = 0; i < 4; i++)
00035         ctx->key[i] = AV_RB32(key + (i << 2));
00036 }
00037 
00038 static void xtea_crypt_ecb(AVXTEA *ctx, uint8_t *dst, const uint8_t *src,
00039                            int decrypt, uint8_t *iv)
00040 {
00041     uint32_t v0, v1;
00042     uint32_t k0 = ctx->key[0];
00043     uint32_t k1 = ctx->key[1];
00044     uint32_t k2 = ctx->key[2];
00045     uint32_t k3 = ctx->key[3];
00046 
00047     v0 = AV_RB32(src);
00048     v1 = AV_RB32(src + 4);
00049 
00050     if (decrypt) {
00051 #if CONFIG_SMALL
00052         int i;
00053         uint32_t delta = 0x9E3779B9U, sum = delta * 32;
00054 
00055         for (i = 0; i < 32; i++) {
00056             v1 -= (((v0 << 4) ^ (v0 >> 5)) + v0) ^ (sum + ctx->key[(sum >> 11) & 3]);
00057             sum -= delta;
00058             v0 -= (((v1 << 4) ^ (v1 >> 5)) + v1) ^ (sum + ctx->key[sum & 3]);
00059         }
00060 #else
00061 #define DSTEP(SUM, K0, K1) \
00062             v1 -= (((v0 << 4) ^ (v0 >> 5)) + v0) ^ (SUM + K0); \
00063             v0 -= (((v1 << 4) ^ (v1 >> 5)) + v1) ^ (SUM - 0x9E3779B9U + K1)
00064 
00065         DSTEP(0xC6EF3720U, k2, k3);
00066         DSTEP(0x28B7BD67U, k3, k2);
00067         DSTEP(0x8A8043AEU, k0, k1);
00068         DSTEP(0xEC48C9F5U, k1, k0);
00069         DSTEP(0x4E11503CU, k2, k3);
00070         DSTEP(0xAFD9D683U, k2, k2);
00071         DSTEP(0x11A25CCAU, k3, k1);
00072         DSTEP(0x736AE311U, k0, k0);
00073         DSTEP(0xD5336958U, k1, k3);
00074         DSTEP(0x36FBEF9FU, k1, k2);
00075         DSTEP(0x98C475E6U, k2, k1);
00076         DSTEP(0xFA8CFC2DU, k3, k0);
00077         DSTEP(0x5C558274U, k0, k3);
00078         DSTEP(0xBE1E08BBU, k1, k2);
00079         DSTEP(0x1FE68F02U, k1, k1);
00080         DSTEP(0x81AF1549U, k2, k0);
00081         DSTEP(0xE3779B90U, k3, k3);
00082         DSTEP(0x454021D7U, k0, k2);
00083         DSTEP(0xA708A81EU, k1, k1);
00084         DSTEP(0x08D12E65U, k1, k0);
00085         DSTEP(0x6A99B4ACU, k2, k3);
00086         DSTEP(0xCC623AF3U, k3, k2);
00087         DSTEP(0x2E2AC13AU, k0, k1);
00088         DSTEP(0x8FF34781U, k0, k0);
00089         DSTEP(0xF1BBCDC8U, k1, k3);
00090         DSTEP(0x5384540FU, k2, k2);
00091         DSTEP(0xB54CDA56U, k3, k1);
00092         DSTEP(0x1715609DU, k0, k0);
00093         DSTEP(0x78DDE6E4U, k0, k3);
00094         DSTEP(0xDAA66D2BU, k1, k2);
00095         DSTEP(0x3C6EF372U, k2, k1);
00096         DSTEP(0x9E3779B9U, k3, k0);
00097 #endif
00098         if (iv) {
00099             v0 ^= AV_RB32(iv);
00100             v1 ^= AV_RB32(iv + 4);
00101             memcpy(iv, src, 8);
00102         }
00103     } else {
00104 #if CONFIG_SMALL
00105         int i;
00106         uint32_t sum = 0, delta = 0x9E3779B9U;
00107 
00108         for (i = 0; i < 32; i++) {
00109             v0 += (((v1 << 4) ^ (v1 >> 5)) + v1) ^ (sum + ctx->key[sum & 3]);
00110             sum += delta;
00111             v1 += (((v0 << 4) ^ (v0 >> 5)) + v0) ^ (sum + ctx->key[(sum >> 11) & 3]);
00112         }
00113 #else
00114 #define ESTEP(SUM, K0, K1) \
00115             v0 += (((v1 << 4) ^ (v1 >> 5)) + v1) ^ (SUM + K0);\
00116             v1 += (((v0 << 4) ^ (v0 >> 5)) + v0) ^ (SUM + 0x9E3779B9U + K1)
00117         ESTEP(0x00000000U, k0, k3);
00118         ESTEP(0x9E3779B9U, k1, k2);
00119         ESTEP(0x3C6EF372U, k2, k1);
00120         ESTEP(0xDAA66D2BU, k3, k0);
00121         ESTEP(0x78DDE6E4U, k0, k0);
00122         ESTEP(0x1715609DU, k1, k3);
00123         ESTEP(0xB54CDA56U, k2, k2);
00124         ESTEP(0x5384540FU, k3, k1);
00125         ESTEP(0xF1BBCDC8U, k0, k0);
00126         ESTEP(0x8FF34781U, k1, k0);
00127         ESTEP(0x2E2AC13AU, k2, k3);
00128         ESTEP(0xCC623AF3U, k3, k2);
00129         ESTEP(0x6A99B4ACU, k0, k1);
00130         ESTEP(0x08D12E65U, k1, k1);
00131         ESTEP(0xA708A81EU, k2, k0);
00132         ESTEP(0x454021D7U, k3, k3);
00133         ESTEP(0xE3779B90U, k0, k2);
00134         ESTEP(0x81AF1549U, k1, k1);
00135         ESTEP(0x1FE68F02U, k2, k1);
00136         ESTEP(0xBE1E08BBU, k3, k0);
00137         ESTEP(0x5C558274U, k0, k3);
00138         ESTEP(0xFA8CFC2DU, k1, k2);
00139         ESTEP(0x98C475E6U, k2, k1);
00140         ESTEP(0x36FBEF9FU, k3, k1);
00141         ESTEP(0xD5336958U, k0, k0);
00142         ESTEP(0x736AE311U, k1, k3);
00143         ESTEP(0x11A25CCAU, k2, k2);
00144         ESTEP(0xAFD9D683U, k3, k2);
00145         ESTEP(0x4E11503CU, k0, k1);
00146         ESTEP(0xEC48C9F5U, k1, k0);
00147         ESTEP(0x8A8043AEU, k2, k3);
00148         ESTEP(0x28B7BD67U, k3, k2);
00149 #endif
00150     }
00151 
00152     AV_WB32(dst, v0);
00153     AV_WB32(dst + 4, v1);
00154 }
00155 
00156 void av_xtea_crypt(AVXTEA *ctx, uint8_t *dst, const uint8_t *src, int count,
00157                    uint8_t *iv, int decrypt)
00158 {
00159     int i;
00160 
00161     if (decrypt) {
00162         while (count--) {
00163             xtea_crypt_ecb(ctx, dst, src, decrypt, iv);
00164 
00165             src   += 8;
00166             dst   += 8;
00167         }
00168     } else {
00169         while (count--) {
00170             if (iv) {
00171                 for (i = 0; i < 8; i++)
00172                     dst[i] = src[i] ^ iv[i];
00173                 xtea_crypt_ecb(ctx, dst, dst, decrypt, NULL);
00174                 memcpy(iv, dst, 8);
00175             } else {
00176                 xtea_crypt_ecb(ctx, dst, src, decrypt, NULL);
00177             }
00178             src   += 8;
00179             dst   += 8;
00180         }
00181     }
00182 }
00183 
00184 #ifdef TEST
00185 #include <stdio.h>
00186 
00187 #define XTEA_NUM_TESTS 6
00188 
00189 static const uint8_t xtea_test_key[XTEA_NUM_TESTS][16] = {
00190     { 0x00, 0x01, 0x02, 0x03, 0x04, 0x05, 0x06, 0x07,
00191       0x08, 0x09, 0x0a, 0x0b, 0x0c, 0x0d, 0x0e, 0x0f },
00192     { 0x00, 0x01, 0x02, 0x03, 0x04, 0x05, 0x06, 0x07,
00193       0x08, 0x09, 0x0a, 0x0b, 0x0c, 0x0d, 0x0e, 0x0f },
00194     { 0x00, 0x01, 0x02, 0x03, 0x04, 0x05, 0x06, 0x07,
00195       0x08, 0x09, 0x0a, 0x0b, 0x0c, 0x0d, 0x0e, 0x0f },
00196     { 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
00197       0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00 },
00198     { 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
00199       0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00 },
00200     { 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
00201       0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00 }
00202 };
00203 
00204 static const uint8_t xtea_test_pt[XTEA_NUM_TESTS][8] = {
00205     { 0x41, 0x42, 0x43, 0x44, 0x45, 0x46, 0x47, 0x48 },
00206     { 0x41, 0x41, 0x41, 0x41, 0x41, 0x41, 0x41, 0x41 },
00207     { 0x5a, 0x5b, 0x6e, 0x27, 0x89, 0x48, 0xd7, 0x7f },
00208     { 0x41, 0x42, 0x43, 0x44, 0x45, 0x46, 0x47, 0x48 },
00209     { 0x41, 0x41, 0x41, 0x41, 0x41, 0x41, 0x41, 0x41 },
00210     { 0x70, 0xe1, 0x22, 0x5d, 0x6e, 0x4e, 0x76, 0x55 }
00211 };
00212 
00213 static const uint8_t xtea_test_ct[XTEA_NUM_TESTS][8] = {
00214     { 0x49, 0x7d, 0xf3, 0xd0, 0x72, 0x61, 0x2c, 0xb5 },
00215     { 0xe7, 0x8f, 0x2d, 0x13, 0x74, 0x43, 0x41, 0xd8 },
00216     { 0x41, 0x41, 0x41, 0x41, 0x41, 0x41, 0x41, 0x41 },
00217     { 0xa0, 0x39, 0x05, 0x89, 0xf8, 0xb8, 0xef, 0xa5 },
00218     { 0xed, 0x23, 0x37, 0x5a, 0x82, 0x1a, 0x8c, 0x2d },
00219     { 0x41, 0x41, 0x41, 0x41, 0x41, 0x41, 0x41, 0x41 }
00220 };
00221 
00222 static void test_xtea(AVXTEA *ctx, uint8_t *dst, const uint8_t *src,
00223                       const uint8_t *ref, int len, uint8_t *iv, int dir,
00224                       const char *test)
00225 {
00226     av_xtea_crypt(ctx, dst, src, len, iv, dir);
00227     if (memcmp(dst, ref, 8*len)) {
00228         int i;
00229         printf("%s failed\ngot      ", test);
00230         for (i = 0; i < 8*len; i++)
00231             printf("%02x ", dst[i]);
00232         printf("\nexpected ");
00233         for (i = 0; i < 8*len; i++)
00234             printf("%02x ", ref[i]);
00235         printf("\n");
00236         exit(1);
00237     }
00238 }
00239 
00240 int main(void)
00241 {
00242     AVXTEA ctx;
00243     uint8_t buf[8], iv[8];
00244     int i;
00245     const uint8_t src[32] = "HelloWorldHelloWorldHelloWorld";
00246     uint8_t ct[32];
00247     uint8_t pl[32];
00248 
00249     for (i = 0; i < XTEA_NUM_TESTS; i++) {
00250         av_xtea_init(&ctx, xtea_test_key[i]);
00251 
00252         test_xtea(&ctx, buf, xtea_test_pt[i], xtea_test_ct[i], 1, NULL, 0, "encryption");
00253         test_xtea(&ctx, buf, xtea_test_ct[i], xtea_test_pt[i], 1, NULL, 1, "decryption");
00254 
00255         /* encrypt */
00256         memcpy(iv, "HALLO123", 8);
00257         av_xtea_crypt(&ctx, ct, src, 4, iv, 0);
00258 
00259         /* decrypt into pl */
00260         memcpy(iv, "HALLO123", 8);
00261         test_xtea(&ctx, pl, ct, src, 4, iv, 1, "CBC decryption");
00262 
00263         memcpy(iv, "HALLO123", 8);
00264         test_xtea(&ctx, ct, ct, src, 4, iv, 1, "CBC inplace decryption");
00265     }
00266 
00267     printf("Test encryption/decryption success.\n");
00268 
00269     return 0;
00270 }
00271 
00272 #endif