We wouldn’t mind tearing down a fingerprint scanner, but we hate to bust up our expensive laptop or cell phone. [Julian], however, got a hold of a fingerprint scanning padlock and was willing to tear it apart for our benefit. The video appears below.
The padlock is a simple enough little device with a cable lock instead of a solid metal shackle, although we have seen similar devices with traditional shackles. Initially, the lock’s fingerprint storage is empty and it will open for any fingerprint. The first task is to set an administrator fingerprint. You’ll need that fingerprint to set up other fingerprints or to reset the unit. Of course, what we are really interested in is what’s inside.
[Julian] heard a motor inside when the lock operates. Once he gets familiar with the basic operation, the tools come out. A padlock should be difficult to crack open, but it looked like it was fairly simple to open. In fact, it looks like the fixed cable anchor screws in, so if you can rotate it enough, you can defeat the lock.
The motor operates a cam when the cable pushes into a microswitch and that cam grabs the locking pin. At first, it didn’t look like there were a lot of electronics inside until the battery came out. Yes, you do have to charge the padlock using USB.
The sensor itself is pretty opaque — just an anonymous module. If you really want to know how they work, we covered that. The lock itself doesn’t seem to be very secure and — as we’ve seen before — fingerprint scanners aren’t that secure anyway.