From 8c3ee93be5ef757b12da81d14029f74c78b942ee Mon Sep 17 00:00:00 2001 From: Giorgio Vazzana Date: Sun, 30 Sep 2012 16:00:19 +0200 Subject: xtea: fix CBC mode when src=dst In CBC mode, when src=dst and we are decrypting a block different from the first one, we need to save the current block of ciphertext (which will constitute the initialization vector for the next block) before we overwrite it. Signed-off-by: Michael Niedermayer --- libavutil/xtea.c | 9 ++++++++- 1 file changed, 8 insertions(+), 1 deletion(-) (limited to 'libavutil/xtea.c') diff --git a/libavutil/xtea.c b/libavutil/xtea.c index bfc613dc47..f2dfe99a46 100644 --- a/libavutil/xtea.c +++ b/libavutil/xtea.c @@ -152,15 +152,22 @@ void av_xtea_crypt(AVXTEA *ctx, uint8_t *dst, const uint8_t *src, int count, uint8_t *iv, int decrypt) { int i; + uint8_t iv_tmp[8]; if (decrypt) { while (count--) { + if (src == dst) + 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]; - memcpy(iv, src, 8); + if (src == dst) + memcpy(iv, iv_tmp, 8); + else + memcpy(iv, src, 8); } src += 8; -- cgit v1.2.3