I am currently working on a project that involves some security hardware. Specifically an electronic door lock. The lock requires the employee to enter a passcode.
This passcode is changed every minute, 24 hours a day, 7 days a week, etc. etc .... The employee carries a little device that calculates this passcode that's based strictly on the current time and date.
Now there are obviously better ways of doing this but there are hardware restrictions. To make things even less secure the engineers made it 4 parts that are merely appended together to form the 12-digit passcode. The passcode will always be 12 digits and any part of that code that makes it less will have leading zeros added to it.
Its was up to me to create an logical alogirthm that would secure this vulnerable system. So although any passcode based on a date and time is not secure I think I did a pretty decent job of hiding it.
So my question is... can someone determine the method I used to encode the date and time given some examples? I figure if you guys cant figure it out then its good enough for the application it will be applied to. Good luck :)
on May 5, 2004 at 8:35 AM the passcode was 201200400175
on October 29, 2003 at 12:57 AM the passcode was 200323671653