From 388b5e69ec51a3c2a526c68149cc58492be3b66e Mon Sep 17 00:00:00 2001
From: Michael Niedermayer <michaelni@gmx.at>
Date: Sun, 14 Jan 2007 16:49:35 +0000
Subject: [PATCH] simplify special round
Originally committed as revision 7481 to svn://svn.ffmpeg.org/ffmpeg/trunk
---
libavutil/aes.c | 10 ++++------
1 file changed, 4 insertions(+), 6 deletions(-)
diff --git a/libavutil/aes.c b/libavutil/aes.c
index 78683b7aca0..3ba5746a6fa 100644
--- a/libavutil/aes.c
+++ b/libavutil/aes.c
@@ -70,10 +70,9 @@ static inline void mix(uint8_t state[4][4], uint32_t multbl[4][256]){
void av_aes_decrypt(AVAES *a){
int t, r;
+ addkey(a->state, a->round_key[a->rounds]);
for(r=a->rounds-1; r>=0; r--){
- if(r==a->rounds-1)
- addkey(a->state, a->round_key[r+1]);
- else
+ if(r!=a->rounds-1)
mix(a->state, dec_multbl);
SUBSHIFT0((a->state[0]+0), inv_sbox)
SUBSHIFT3((a->state[0]+1), inv_sbox)
@@ -92,11 +91,10 @@ void av_aes_encrypt(AVAES *a){
SUBSHIFT1((a->state[0]+1), sbox)
SUBSHIFT2((a->state[0]+2), sbox)
SUBSHIFT3((a->state[0]+3), sbox)
- if(r==a->rounds-1)
- addkey(a->state, a->round_key[r+1]);
- else
+ if(r!=a->rounds-1)
mix(a->state, enc_multbl); //FIXME replace log8 by const / optimze mix as this can be simplified alot
}
+ addkey(a->state, a->round_key[r]);
}
static init_multbl(uint8_t tbl[256], int c[4], uint8_t *log8, uint8_t *alog8){
--
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