/* * A 32-bit implementation of the XTEA algorithm * Copyright (c) 2012 Samuel Pitoiset * * loosely based on the implementation of David Wheeler and Roger Needham * * This file is part of Libav. * * Libav is free software; you can redistribute it and/or * 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. * * Libav is distributed in the hope that it will be useful, * 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 * License along with Libav; if not, write to the Free Software * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA */ /** * @file * @brief XTEA 32-bit implementation * @author Samuel Pitoiset * @ingroup lavu_xtea */ #include "avutil.h" #include "common.h" #include "intreadwrite.h" #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, int decrypt, uint8_t *iv) { uint32_t v0, v1; int i; v0 = AV_RB32(src); v1 = AV_RB32(src + 4); if (decrypt) { uint32_t delta = 0x9E3779B9, sum = delta * 32; 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]); } if (iv) { v0 ^= AV_RB32(iv); v1 ^= AV_RB32(iv + 4); memcpy(iv, src, 8); } } else { uint32_t sum = 0, delta = 0x9E3779B9; 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]); } } 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; if (decrypt) { while (count--) { xtea_crypt_ecb(ctx, dst, src, decrypt, iv); src += 8; dst += 8; } } else { while (count--) { if (iv) { for (i = 0; i < 8; i++) dst[i] = src[i] ^ iv[i]; xtea_crypt_ecb(ctx, dst, dst, decrypt, NULL); memcpy(iv, dst, 8); } else { xtea_crypt_ecb(ctx, dst, src, decrypt, NULL); } src += 8; dst += 8; } } } #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 } }; 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); } } int main(void) { AVXTEA ctx; uint8_t buf[8], iv[8]; int i; const uint8_t src[32] = "HelloWorldHelloWorldHelloWorld"; uint8_t ct[32]; uint8_t pl[32]; for (i = 0; i < XTEA_NUM_TESTS; i++) { av_xtea_init(&ctx, xtea_test_key[i]); 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"); /* encrypt */ memcpy(iv, "HALLO123", 8); av_xtea_crypt(&ctx, ct, src, 4, iv, 0); /* decrypt into pl */ memcpy(iv, "HALLO123", 8); test_xtea(&ctx, pl, ct, src, 4, iv, 1, "CBC decryption"); memcpy(iv, "HALLO123", 8); test_xtea(&ctx, ct, ct, src, 4, iv, 1, "CBC inplace decryption"); } printf("Test encryption/decryption success.\n"); return 0; } #endif