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xtea: move iv decrypt handling code into xtea_crypt_ecb() 

this simplifies things are avoids a temporary

Signed-off-by: Michael Niedermayer <michaelni@gmx.at>
This commit is contained in:
Michael Niedermayer 2012-09-30 17:46:37 +02:00
parent a4dcdd04d7
commit 48154c2594
1 changed files with 9 additions and 17 deletions
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26
libavutil/xtea.c
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@ -36,7 +36,7 @@ void av_xtea_init(AVXTEA *ctx, const uint8_t key[16])
} }
static void xtea_crypt_ecb(AVXTEA *ctx, uint8_t *dst, const uint8_t *src, static void xtea_crypt_ecb(AVXTEA *ctx, uint8_t *dst, const uint8_t *src,
int decrypt) int decrypt, uint8_t *iv)
{ {
uint32_t v0, v1; uint32_t v0, v1;
uint32_t k0 = ctx->key[0]; uint32_t k0 = ctx->key[0];
@ -94,6 +94,11 @@ static void xtea_crypt_ecb(AVXTEA *ctx, uint8_t *dst, const uint8_t *src,
DSTEP(0xDAA66D2BU, k1, k2); DSTEP(0xDAA66D2BU, k1, k2);
DSTEP(0x3C6EF372U, k2, k1); DSTEP(0x3C6EF372U, k2, k1);
DSTEP(0x9E3779B9U, k3, k0); DSTEP(0x9E3779B9U, k3, k0);
if(iv){
v0 ^= AV_RB32(iv );
v1 ^= AV_RB32(iv+4);
memcpy(iv, src, 8);
}
#endif #endif
} else { } else {
#if CONFIG_SMALL #if CONFIG_SMALL
@ -152,23 +157,10 @@ void av_xtea_crypt(AVXTEA *ctx, uint8_t *dst, const uint8_t *src, int count,
uint8_t *iv, int decrypt) uint8_t *iv, int decrypt)
{ {
int i; int i;
uint8_t iv_tmp[8];
if (decrypt) { if (decrypt) {
while (count--) { while (count--) {
if (src == dst) xtea_crypt_ecb(ctx, dst, src, decrypt, iv);
memcpy(iv_tmp, src, 8);
xtea_crypt_ecb(ctx, dst, src, decrypt);
if (iv) {
for (i = 0; i < 8; i++)
dst[i] = dst[i] ^ iv[i];
if (src == dst)
memcpy(iv, iv_tmp, 8);
else
memcpy(iv, src, 8);
}
src += 8; src += 8;
dst += 8; dst += 8;
@ -178,10 +170,10 @@ void av_xtea_crypt(AVXTEA *ctx, uint8_t *dst, const uint8_t *src, int count,
if (iv) { if (iv) {
for (i = 0; i < 8; i++) for (i = 0; i < 8; i++)
dst[i] = src[i] ^ iv[i]; dst[i] = src[i] ^ iv[i];
xtea_crypt_ecb(ctx, dst, dst, decrypt); xtea_crypt_ecb(ctx, dst, dst, decrypt, NULL);
memcpy(iv, dst, 8); memcpy(iv, dst, 8);
} else { } else {
xtea_crypt_ecb(ctx, dst, src, decrypt); xtea_crypt_ecb(ctx, dst, src, decrypt, NULL);
} }
src += 8; src += 8;
dst += 8; dst += 8;