254 lines
7.4 KiB
C
254 lines
7.4 KiB
C
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/*
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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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/**
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* @file
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* @brief XTEA 32-bit implementation
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* @author Samuel Pitoiset
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* @ingroup lavu_xtea
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*/
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#include "avutil.h"
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#include "common.h"
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#include "intreadwrite.h"
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#include "mem.h"
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#include "xtea.h"
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AVXTEA *av_xtea_alloc(void)
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{
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return av_mallocz(sizeof(struct AVXTEA));
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}
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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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void av_xtea_le_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_RL32(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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static void xtea_le_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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int i;
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v0 = AV_RL32(src);
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v1 = AV_RL32(src + 4);
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if (decrypt) {
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uint32_t delta = 0x9E3779B9, 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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if (iv) {
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v0 ^= AV_RL32(iv);
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v1 ^= AV_RL32(iv + 4);
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memcpy(iv, src, 8);
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}
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} else {
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uint32_t sum = 0, delta = 0x9E3779B9;
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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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}
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AV_WL32(dst, v0);
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AV_WL32(dst + 4, v1);
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}
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static void 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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void (*crypt)(AVXTEA *, uint8_t *, const uint8_t *, int, uint8_t *))
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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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crypt(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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crypt(ctx, dst, dst, decrypt, NULL);
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memcpy(iv, dst, 8);
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} else {
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crypt(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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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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xtea_crypt(ctx, dst, src, count, iv, decrypt, xtea_crypt_ecb);
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}
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void av_xtea_le_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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xtea_crypt(ctx, dst, src, count, iv, decrypt, xtea_le_crypt_ecb);
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}
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