275 lines
8.5 KiB
C
275 lines
8.5 KiB
C
/*
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* A 32-bit implementation of the XTEA algorithm
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* Copyright (c) 2012 Samuel Pitoiset
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*
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* loosely based on the implementation of David Wheeler and Roger Needham
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*
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* This file is part of FFmpeg.
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*
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* FFmpeg is free software; you can redistribute it and/or
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* modify it under the terms of the GNU Lesser General Public
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* License as published by the Free Software Foundation; either
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* version 2.1 of the License, or (at your option) any later version.
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*
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* FFmpeg is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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* Lesser General Public License for more details.
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*
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* You should have received a copy of the GNU Lesser General Public
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* License along with FFmpeg; if not, write to the Free Software
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* Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
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*/
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#include "libavutil/intreadwrite.h"
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#include "avutil.h"
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#include "common.h"
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#include "xtea.h"
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void av_xtea_init(AVXTEA *ctx, const uint8_t key[16])
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{
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int i;
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for (i = 0; i < 4; i++)
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ctx->key[i] = AV_RB32(key + (i << 2));
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}
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static void xtea_crypt_ecb(AVXTEA *ctx, uint8_t *dst, const uint8_t *src,
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int decrypt, uint8_t *iv)
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{
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uint32_t v0, v1;
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#if !CONFIG_SMALL
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uint32_t k0 = ctx->key[0];
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uint32_t k1 = ctx->key[1];
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uint32_t k2 = ctx->key[2];
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uint32_t k3 = ctx->key[3];
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#endif
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v0 = AV_RB32(src);
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v1 = AV_RB32(src + 4);
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if (decrypt) {
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#if CONFIG_SMALL
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int i;
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uint32_t delta = 0x9E3779B9U, sum = delta * 32;
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for (i = 0; i < 32; i++) {
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v1 -= (((v0 << 4) ^ (v0 >> 5)) + v0) ^ (sum + ctx->key[(sum >> 11) & 3]);
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sum -= delta;
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v0 -= (((v1 << 4) ^ (v1 >> 5)) + v1) ^ (sum + ctx->key[sum & 3]);
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}
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#else
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#define DSTEP(SUM, K0, K1) \
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v1 -= (((v0 << 4) ^ (v0 >> 5)) + v0) ^ (SUM + K0); \
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v0 -= (((v1 << 4) ^ (v1 >> 5)) + v1) ^ (SUM - 0x9E3779B9U + K1)
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DSTEP(0xC6EF3720U, k2, k3);
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DSTEP(0x28B7BD67U, k3, k2);
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DSTEP(0x8A8043AEU, k0, k1);
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DSTEP(0xEC48C9F5U, k1, k0);
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DSTEP(0x4E11503CU, k2, k3);
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DSTEP(0xAFD9D683U, k2, k2);
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DSTEP(0x11A25CCAU, k3, k1);
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DSTEP(0x736AE311U, k0, k0);
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DSTEP(0xD5336958U, k1, k3);
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DSTEP(0x36FBEF9FU, k1, k2);
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DSTEP(0x98C475E6U, k2, k1);
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DSTEP(0xFA8CFC2DU, k3, k0);
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DSTEP(0x5C558274U, k0, k3);
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DSTEP(0xBE1E08BBU, k1, k2);
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DSTEP(0x1FE68F02U, k1, k1);
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DSTEP(0x81AF1549U, k2, k0);
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DSTEP(0xE3779B90U, k3, k3);
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DSTEP(0x454021D7U, k0, k2);
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DSTEP(0xA708A81EU, k1, k1);
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DSTEP(0x08D12E65U, k1, k0);
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DSTEP(0x6A99B4ACU, k2, k3);
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DSTEP(0xCC623AF3U, k3, k2);
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DSTEP(0x2E2AC13AU, k0, k1);
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DSTEP(0x8FF34781U, k0, k0);
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DSTEP(0xF1BBCDC8U, k1, k3);
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DSTEP(0x5384540FU, k2, k2);
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DSTEP(0xB54CDA56U, k3, k1);
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DSTEP(0x1715609DU, k0, k0);
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DSTEP(0x78DDE6E4U, k0, k3);
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DSTEP(0xDAA66D2BU, k1, k2);
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DSTEP(0x3C6EF372U, k2, k1);
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DSTEP(0x9E3779B9U, k3, k0);
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#endif
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if (iv) {
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v0 ^= AV_RB32(iv);
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v1 ^= AV_RB32(iv + 4);
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memcpy(iv, src, 8);
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}
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} else {
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#if CONFIG_SMALL
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int i;
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uint32_t sum = 0, delta = 0x9E3779B9U;
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for (i = 0; i < 32; i++) {
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v0 += (((v1 << 4) ^ (v1 >> 5)) + v1) ^ (sum + ctx->key[sum & 3]);
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sum += delta;
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v1 += (((v0 << 4) ^ (v0 >> 5)) + v0) ^ (sum + ctx->key[(sum >> 11) & 3]);
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}
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#else
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#define ESTEP(SUM, K0, K1) \
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v0 += (((v1 << 4) ^ (v1 >> 5)) + v1) ^ (SUM + K0);\
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v1 += (((v0 << 4) ^ (v0 >> 5)) + v0) ^ (SUM + 0x9E3779B9U + K1)
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ESTEP(0x00000000U, k0, k3);
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ESTEP(0x9E3779B9U, k1, k2);
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ESTEP(0x3C6EF372U, k2, k1);
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ESTEP(0xDAA66D2BU, k3, k0);
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ESTEP(0x78DDE6E4U, k0, k0);
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ESTEP(0x1715609DU, k1, k3);
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ESTEP(0xB54CDA56U, k2, k2);
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ESTEP(0x5384540FU, k3, k1);
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ESTEP(0xF1BBCDC8U, k0, k0);
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ESTEP(0x8FF34781U, k1, k0);
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ESTEP(0x2E2AC13AU, k2, k3);
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ESTEP(0xCC623AF3U, k3, k2);
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ESTEP(0x6A99B4ACU, k0, k1);
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ESTEP(0x08D12E65U, k1, k1);
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ESTEP(0xA708A81EU, k2, k0);
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ESTEP(0x454021D7U, k3, k3);
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ESTEP(0xE3779B90U, k0, k2);
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ESTEP(0x81AF1549U, k1, k1);
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ESTEP(0x1FE68F02U, k2, k1);
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ESTEP(0xBE1E08BBU, k3, k0);
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ESTEP(0x5C558274U, k0, k3);
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ESTEP(0xFA8CFC2DU, k1, k2);
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ESTEP(0x98C475E6U, k2, k1);
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ESTEP(0x36FBEF9FU, k3, k1);
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ESTEP(0xD5336958U, k0, k0);
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ESTEP(0x736AE311U, k1, k3);
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ESTEP(0x11A25CCAU, k2, k2);
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ESTEP(0xAFD9D683U, k3, k2);
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ESTEP(0x4E11503CU, k0, k1);
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ESTEP(0xEC48C9F5U, k1, k0);
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ESTEP(0x8A8043AEU, k2, k3);
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ESTEP(0x28B7BD67U, k3, k2);
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#endif
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}
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AV_WB32(dst, v0);
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AV_WB32(dst + 4, v1);
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}
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void av_xtea_crypt(AVXTEA *ctx, uint8_t *dst, const uint8_t *src, int count,
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uint8_t *iv, int decrypt)
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{
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int i;
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if (decrypt) {
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while (count--) {
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xtea_crypt_ecb(ctx, dst, src, decrypt, iv);
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src += 8;
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dst += 8;
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}
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} else {
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while (count--) {
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if (iv) {
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for (i = 0; i < 8; i++)
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dst[i] = src[i] ^ iv[i];
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xtea_crypt_ecb(ctx, dst, dst, decrypt, NULL);
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memcpy(iv, dst, 8);
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} else {
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xtea_crypt_ecb(ctx, dst, src, decrypt, NULL);
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}
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src += 8;
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dst += 8;
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}
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}
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}
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#ifdef TEST
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#include <stdio.h>
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#define XTEA_NUM_TESTS 6
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static const uint8_t xtea_test_key[XTEA_NUM_TESTS][16] = {
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{ 0x00, 0x01, 0x02, 0x03, 0x04, 0x05, 0x06, 0x07,
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0x08, 0x09, 0x0a, 0x0b, 0x0c, 0x0d, 0x0e, 0x0f },
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{ 0x00, 0x01, 0x02, 0x03, 0x04, 0x05, 0x06, 0x07,
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0x08, 0x09, 0x0a, 0x0b, 0x0c, 0x0d, 0x0e, 0x0f },
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{ 0x00, 0x01, 0x02, 0x03, 0x04, 0x05, 0x06, 0x07,
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0x08, 0x09, 0x0a, 0x0b, 0x0c, 0x0d, 0x0e, 0x0f },
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{ 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
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0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00 },
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{ 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
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0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00 },
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{ 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
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0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00 }
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};
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static const uint8_t xtea_test_pt[XTEA_NUM_TESTS][8] = {
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{ 0x41, 0x42, 0x43, 0x44, 0x45, 0x46, 0x47, 0x48 },
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{ 0x41, 0x41, 0x41, 0x41, 0x41, 0x41, 0x41, 0x41 },
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{ 0x5a, 0x5b, 0x6e, 0x27, 0x89, 0x48, 0xd7, 0x7f },
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{ 0x41, 0x42, 0x43, 0x44, 0x45, 0x46, 0x47, 0x48 },
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{ 0x41, 0x41, 0x41, 0x41, 0x41, 0x41, 0x41, 0x41 },
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{ 0x70, 0xe1, 0x22, 0x5d, 0x6e, 0x4e, 0x76, 0x55 }
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};
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static const uint8_t xtea_test_ct[XTEA_NUM_TESTS][8] = {
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{ 0x49, 0x7d, 0xf3, 0xd0, 0x72, 0x61, 0x2c, 0xb5 },
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{ 0xe7, 0x8f, 0x2d, 0x13, 0x74, 0x43, 0x41, 0xd8 },
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{ 0x41, 0x41, 0x41, 0x41, 0x41, 0x41, 0x41, 0x41 },
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{ 0xa0, 0x39, 0x05, 0x89, 0xf8, 0xb8, 0xef, 0xa5 },
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{ 0xed, 0x23, 0x37, 0x5a, 0x82, 0x1a, 0x8c, 0x2d },
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{ 0x41, 0x41, 0x41, 0x41, 0x41, 0x41, 0x41, 0x41 }
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};
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static void test_xtea(AVXTEA *ctx, uint8_t *dst, const uint8_t *src,
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const uint8_t *ref, int len, uint8_t *iv, int dir,
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const char *test)
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{
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av_xtea_crypt(ctx, dst, src, len, iv, dir);
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if (memcmp(dst, ref, 8*len)) {
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int i;
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printf("%s failed\ngot ", test);
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for (i = 0; i < 8*len; i++)
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printf("%02x ", dst[i]);
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printf("\nexpected ");
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for (i = 0; i < 8*len; i++)
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printf("%02x ", ref[i]);
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printf("\n");
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exit(1);
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}
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}
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int main(void)
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{
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AVXTEA ctx;
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uint8_t buf[8], iv[8];
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int i;
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const uint8_t src[32] = "HelloWorldHelloWorldHelloWorld";
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uint8_t ct[32];
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uint8_t pl[32];
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for (i = 0; i < XTEA_NUM_TESTS; i++) {
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av_xtea_init(&ctx, xtea_test_key[i]);
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test_xtea(&ctx, buf, xtea_test_pt[i], xtea_test_ct[i], 1, NULL, 0, "encryption");
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test_xtea(&ctx, buf, xtea_test_ct[i], xtea_test_pt[i], 1, NULL, 1, "decryption");
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/* encrypt */
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memcpy(iv, "HALLO123", 8);
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av_xtea_crypt(&ctx, ct, src, 4, iv, 0);
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/* decrypt into pl */
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memcpy(iv, "HALLO123", 8);
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test_xtea(&ctx, pl, ct, src, 4, iv, 1, "CBC decryption");
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memcpy(iv, "HALLO123", 8);
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test_xtea(&ctx, ct, ct, src, 4, iv, 1, "CBC inplace decryption");
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}
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printf("Test encryption/decryption success.\n");
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return 0;
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}
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#endif
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