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/*
* 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 "mem.h"
#include "xtea.h"
#if !FF_API_CRYPTO_CONTEXT
struct AVXTEA {
uint32_t key[16];
};
#endif
AVXTEA *av_xtea_alloc(void)
{
return av_mallocz(sizeof(struct AVXTEA));
}
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));
}
void av_xtea_le_init(AVXTEA *ctx, const uint8_t key[16])
{
int i;
for (i = 0; i < 4; i++)
ctx->key[i] = AV_RL32(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);
}
static void xtea_le_crypt_ecb(AVXTEA *ctx, uint8_t *dst, const uint8_t *src,
int decrypt, uint8_t *iv)
{
uint32_t v0, v1;
int i;
v0 = AV_RL32(src);
v1 = AV_RL32(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_RL32(iv);
v1 ^= AV_RL32(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_WL32(dst, v0);
AV_WL32(dst + 4, v1);
}
static void xtea_crypt(AVXTEA *ctx, uint8_t *dst, const uint8_t *src, int count,
uint8_t *iv, int decrypt,
void (*crypt)(AVXTEA *, uint8_t *, const uint8_t *, int, uint8_t *))
{
int i;
if (decrypt) {
while (count--) {
crypt(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];
crypt(ctx, dst, dst, decrypt, NULL);
memcpy(iv, dst, 8);
} else {
crypt(ctx, dst, src, decrypt, NULL);
}
src += 8;
dst += 8;
}
}
}
void av_xtea_crypt(AVXTEA *ctx, uint8_t *dst, const uint8_t *src, int count,
uint8_t *iv, int decrypt)
{
xtea_crypt(ctx, dst, src, count, iv, decrypt, xtea_crypt_ecb);
}
void av_xtea_le_crypt(AVXTEA *ctx, uint8_t *dst, const uint8_t *src, int count,
uint8_t *iv, int decrypt)
{
xtea_crypt(ctx, dst, src, count, iv, decrypt, xtea_le_crypt_ecb);
}
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