From fe2cff4a622a2f046d224774fd257d0433888b78 Mon Sep 17 00:00:00 2001
From: Christian Pointner <equinox@spreadspace.org>
Date: Tue, 29 Jan 2013 20:49:48 +0000
Subject: some more cleanup acutally using constant time compare :)

git-svn-id: https://svn.spreadspace.org/avr/trunk@94 aa12f405-d877-488e-9caf-2d797e2a1cc7
---
 usb-i2c-sl018/tuer-rfid.c | 12 +++++++-----
 1 file changed, 7 insertions(+), 5 deletions(-)

(limited to 'usb-i2c-sl018')

diff --git a/usb-i2c-sl018/tuer-rfid.c b/usb-i2c-sl018/tuer-rfid.c
index e51e361..e991302 100644
--- a/usb-i2c-sl018/tuer-rfid.c
+++ b/usb-i2c-sl018/tuer-rfid.c
@@ -306,11 +306,11 @@ uint8_t generate_csum(uint8_t* data)
   return sum2<<4 | sum1;
 }
 
-bool compare_keyslots(const keyslot_t* a, const keyslot_t* b) // constant time compare
+uint8_t compare_keyslots(const keyslot_t* a, const keyslot_t* b) // constant time compare
 {
   uint8_t tmp=0, i;
   for(i=0; i<sizeof(keyslot_t); ++i)
-    tmp |= (a->byte[i] ^ a->byte[i]);
+    tmp |= a->byte[i] ^ b->byte[i];
 
   return tmp;
 }
@@ -323,12 +323,12 @@ bool check_card(const uint8_t * uid, uint8_t uid_len)
   uid_len = uid_len > sizeof(keyslot_t) ? sizeof(keyslot_t) : uid_len;
   for (uint8_t pos=0; pos<uid_len; pos++)
     card.byte[pos]=uid[uid_len-pos-1];
-  card.byte[sizeof(keyslot_t) - 1]=generate_csum(&card.byte[0]);
+  card.byte[sizeof(keyslot_t) - 1]=generate_csum(card.byte);
   keyslot_t * ks=keyslots;
   bool valid=0;
   for(uint8_t ks_num=0;ks_num<(EEPROM_SIZE/sizeof(card));ks_num++) {
     eeprom_read_block(&eeprom_ks,&ks[ks_num],sizeof(eeprom_ks));
-    if(card.uint64==eeprom_ks.uint64) {
+    if(!compare_keyslots(&card, &eeprom_ks)) {
       valid=1;
       // break;  // this would break security (not const time)
     }
@@ -353,9 +353,11 @@ void handle_card(void)
     if (0<type && type < 7) {
       if(check_card(recv_twi_msg->data,uid_len)) {
         sl018_cmd(SL018CMD_ComRedLedOn);
-        fprintf(stdio,"open/close\n\r"); // TODO: open/close door!
+        fprintf(stdio,"Card allowed - opening/closing door\n\r"); // TODO: open/close door!
         _delay_ms(255);
         sl018_cmd(SL018CMD_ComRedLedOff);
+      } else {
+        fprintf(stdio,"Card not found in Database\n\r");
       }
     } else {
       fprintf(stdio,"Unknown Card Type %02x\n\r",type);
-- 
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