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Diffstat (limited to 'libavutil/xtea.c')
| -rw-r--r-- | libavutil/xtea.c | 165 |
1 files changed, 165 insertions, 0 deletions
diff --git a/libavutil/xtea.c b/libavutil/xtea.c new file mode 100644 index 0000000000..138657f88b --- /dev/null +++ b/libavutil/xtea.c @@ -0,0 +1,165 @@ +/* + * 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 + */ + +#include "libavutil/intreadwrite.h" + +#include "avutil.h" +#include "common.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) +{ + 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]); + } + } 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; + + while (count > 0) { + if (decrypt) { + xtea_crypt_ecb(ctx, dst, src, decrypt); + + if (iv) { + for (i = 0; i < 8; i++) + dst[i] = dst[i] ^ iv[i]; + memcpy(iv, src, 8); + } + } else { + if (iv) { + for (i = 0; i < 8; i++) + dst[i] = src[i] ^ iv[i]; + xtea_crypt_ecb(ctx, dst, dst, decrypt); + memcpy(iv, dst, 8); + } else { + xtea_crypt_ecb(ctx, dst, src, decrypt); + } + } + + src += 8; + dst += 8; + count -= 8; + } +} + +#ifdef TEST +#include <stdio.h> +#undef printf + +#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 } +}; + +int main(void) +{ + AVXTEA ctx; + uint8_t buf[8]; + int i; + + for (i = 0; i < XTEA_NUM_TESTS; i++) { + av_xtea_init(&ctx, xtea_test_key[i]); + + av_xtea_crypt(&ctx, buf, xtea_test_pt[i], 1, NULL, 0); + if (memcmp(buf, xtea_test_ct[i], 8)) { + printf("Test encryption failed.\n"); + return 1; + } + + av_xtea_crypt(&ctx, buf, xtea_test_ct[i], 1, NULL, 1); + if (memcmp(buf, xtea_test_pt[i], 8)) { + printf("Test decryption failed.\n"); + return 1; + } + } + printf("Test encryption/decryption success.\n"); + + return 0; +} + +#endif |