some more cleanup

acutally using constant time compare :)


git-svn-id: https://svn.spreadspace.org/avr/trunk@94 aa12f405-d877-488e-9caf-2d797e2a1cc7

1 files changed, 7 insertions, 5 deletions

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);