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xtea: Fix CBC decryption when src==dst

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Signed-off-by: Martin Storsjö <martin@martin.st>
This commit is contained in:
Michael Niedermayer 2012-09-30 17:46:37 +02:00 committed by Martin Storsjö
parent ca074cc313
commit b434500431
1 changed files with 9 additions and 10 deletions
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19
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;
int i; int i;
@ -52,6 +52,11 @@ static void xtea_crypt_ecb(AVXTEA *ctx, uint8_t *dst, const uint8_t *src,
sum -= delta; sum -= delta;
v0 -= (((v1 << 4) ^ (v1 >> 5)) + v1) ^ (sum + ctx->key[sum & 3]); 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 { } else {
uint32_t sum = 0, delta = 0x9E3779B9; uint32_t sum = 0, delta = 0x9E3779B9;
@ -73,13 +78,7 @@ void av_xtea_crypt(AVXTEA *ctx, uint8_t *dst, const uint8_t *src, int count,
if (decrypt) { if (decrypt) {
while (count--) { while (count--) {
xtea_crypt_ecb(ctx, dst, src, decrypt); xtea_crypt_ecb(ctx, dst, src, decrypt, iv);
if (iv) {
for (i = 0; i < 8; i++)
dst[i] = dst[i] ^ iv[i];
memcpy(iv, src, 8);
}
src += 8; src += 8;
dst += 8; dst += 8;
@ -89,10 +88,10 @@ 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;