big bug fixed, still some problems with flow control

[avr-crypto-lib.git] / aes_dec.c

diff --git a/aes_dec.c b/aes_dec.c
index 48ad3b47986b61a1f6b764b3f40d136f20767d7f..8c476de0dbe70d3105eda6412befb75f334e78ba 100644 (file)
--- a/aes_dec.c
+++ b/aes_dec.c
@@ -1,6 +1,6 @@
 /* aes.c */
 /*
-    This file is part of the Crypto-avr-lib/microcrypt-lib.
+    This file is part of the AVR-Crypto-Lib.
     Copyright (C) 2008, 2009  Daniel Otte (daniel.otte@rub.de)
 
     This program is free software: you can redistribute it and/or modify
@@ -49,12 +49,25 @@ static
 void aes_dec_round(aes_cipher_state_t* state, const aes_roundkey_t* k){
        uint8_t tmp[16];
        uint8_t i;
+       uint8_t t,u,v,w;
        /* keyAdd */
        for(i=0; i<16; ++i){
                tmp[i] = state->s[i] ^ k->ks[i];
        }
        /* mixColums */
        for(i=0; i<4; ++i){
+               t = tmp[4*i+3] ^ tmp[4*i+2];
+               u = tmp[4*i+1] ^ tmp[4*i+0];
+               v = t ^ u;
+               v = gf256mul(0x09, v, 0x1b);
+               w = v ^ gf256mul(0x04, tmp[4*i+2] ^ tmp[4*i+0], 0x1b);
+               v = v ^ gf256mul(0x04, tmp[4*i+3] ^ tmp[4*i+1], 0x1b);
+               state->s[4*i+3] = tmp[4*i+3] ^ v ^ gf256mul(0x02, tmp[4*i+0] ^ tmp[4*i+3], 0x1b);
+               state->s[4*i+2] = tmp[4*i+2] ^ w ^ gf256mul(0x02, t, 0x1b);
+               state->s[4*i+1] = tmp[4*i+1] ^ v ^ gf256mul(0x02, tmp[4*i+2] ^ tmp[4*i+1], 0x1b);
+               state->s[4*i+0] = tmp[4*i+0] ^ w ^ gf256mul(0x02, u, 0x1b);
+               
+               /*
                state->s[4*i+0] =
                          gf256mul(0xe, tmp[4*i+0], 0x1b)
                        ^ gf256mul(0xb, tmp[4*i+1], 0x1b)
@@ -75,6 +88,7 @@ void aes_dec_round(aes_cipher_state_t* state, const aes_roundkey_t* k){
                        ^ gf256mul(0xd, tmp[4*i+1], 0x1b)
                        ^ gf256mul(0x9, tmp[4*i+2], 0x1b)
                        ^ gf256mul(0xe, tmp[4*i+3], 0x1b);
+               */
        }       
        /* shiftRows */
        aes_invshiftcol(state->s+1, 1);