X-Git-Url: https://git.cryptolib.org/?a=blobdiff_plain;f=aes_dec.c;h=8c476de0dbe70d3105eda6412befb75f334e78ba;hb=402f8b98e8bd4ca12bbac8fe6ccd07e594015a63;hp=3b546411aba18aa7ae082a8aad7565ee9939213c;hpb=d6a35f05fd2b5ee79d5ad8424434ad1a068be453;p=avr-crypto-lib.git

diff --git a/aes_dec.c b/aes_dec.c
index 3b54641..8c476de 100644
--- a/aes_dec.c
+++ b/aes_dec.c
@@ -1,7 +1,7 @@
 /* aes.c */
 /*
-    This file is part of the Crypto-avr-lib/microcrypt-lib.
-    Copyright (C) 2008  Daniel Otte (daniel.otte@rub.de)
+    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
     it under the terms of the GNU General Public License as published by
@@ -34,41 +34,66 @@ void aes_invshiftrow(void* data, uint8_t shift){
 	memcpy(data, tmp, 4);
 }
 
+void aes_invshiftcol(void* data, uint8_t shift){
+	uint8_t tmp[4];
+	tmp[0] = ((uint8_t*)data)[ 0];
+	tmp[1] = ((uint8_t*)data)[ 4];
+	tmp[2] = ((uint8_t*)data)[ 8];
+	tmp[3] = ((uint8_t*)data)[12];
+	((uint8_t*)data)[ 0] = tmp[(4-shift+0)&3];
+	((uint8_t*)data)[ 4] = tmp[(4-shift+1)&3];
+	((uint8_t*)data)[ 8] = tmp[(4-shift+2)&3];
+	((uint8_t*)data)[12] = tmp[(4-shift+3)&3];
+}
 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){
-		state->s[4*0+i] =
-			  gf256mul(0xe, tmp[4*0+i], 0x1b)
-			^ gf256mul(0xb, tmp[4*1+i], 0x1b)
-			^ gf256mul(0xd, tmp[4*2+i], 0x1b)
-			^ gf256mul(0x9, tmp[4*3+i], 0x1b);
-		state->s[4*1+i] =
-			  gf256mul(0x9, tmp[4*0+i], 0x1b)
-			^ gf256mul(0xe, tmp[4*1+i], 0x1b)
-			^ gf256mul(0xb, tmp[4*2+i], 0x1b)
-			^ gf256mul(0xd, tmp[4*3+i], 0x1b);
-		state->s[4*2+i] =
-			  gf256mul(0xd, tmp[4*0+i], 0x1b)
-			^ gf256mul(0x9, tmp[4*1+i], 0x1b)
-			^ gf256mul(0xe, tmp[4*2+i], 0x1b)
-			^ gf256mul(0xb, tmp[4*3+i], 0x1b);
-		state->s[4*3+i] =
-			  gf256mul(0xb, tmp[4*0+i], 0x1b)
-			^ gf256mul(0xd, tmp[4*1+i], 0x1b)
-			^ gf256mul(0x9, tmp[4*2+i], 0x1b)
-			^ gf256mul(0xe, tmp[4*3+i], 0x1b);
+		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)
+			^ gf256mul(0xd, tmp[4*i+2], 0x1b)
+			^ gf256mul(0x9, tmp[4*i+3], 0x1b);
+		state->s[4*i+1] =
+			  gf256mul(0x9, tmp[4*i+0], 0x1b)
+			^ gf256mul(0xe, tmp[4*i+1], 0x1b)
+			^ gf256mul(0xb, tmp[4*i+2], 0x1b)
+			^ gf256mul(0xd, tmp[4*i+3], 0x1b);
+		state->s[4*i+2] =
+			  gf256mul(0xd, tmp[4*i+0], 0x1b)
+			^ gf256mul(0x9, tmp[4*i+1], 0x1b)
+			^ gf256mul(0xe, tmp[4*i+2], 0x1b)
+			^ gf256mul(0xb, tmp[4*i+3], 0x1b);
+		state->s[4*i+3] =
+			  gf256mul(0xb, tmp[4*i+0], 0x1b)
+			^ gf256mul(0xd, tmp[4*i+1], 0x1b)
+			^ gf256mul(0x9, tmp[4*i+2], 0x1b)
+			^ gf256mul(0xe, tmp[4*i+3], 0x1b);
+		*/
 	}	
 	/* shiftRows */
-	aes_invshiftrow(state->s+4, 1);
-	aes_invshiftrow(state->s+8, 2);
-	aes_invshiftrow(state->s+12, 3);		
+	aes_invshiftcol(state->s+1, 1);
+	aes_invshiftcol(state->s+2, 2);
+	aes_invshiftcol(state->s+3, 3);		
 	/* subBytes */
 	for(i=0; i<16; ++i){
 		state->s[i] = pgm_read_byte(aes_invsbox+state->s[i]);
@@ -84,9 +109,9 @@ void aes_dec_firstround(aes_cipher_state_t* state, const aes_roundkey_t* k){
 		state->s[i] ^= k->ks[i];
 	}
 	/* shiftRows */
-	aes_invshiftrow(state->s+4, 1);
-	aes_invshiftrow(state->s+8, 2);
-	aes_invshiftrow(state->s+12, 3);		
+	aes_invshiftcol(state->s+1, 1);
+	aes_invshiftcol(state->s+2, 2);
+	aes_invshiftcol(state->s+3, 3);		
 	/* subBytes */
 	for(i=0; i<16; ++i){
 		state->s[i] = pgm_read_byte(aes_invsbox+state->s[i]);