[eecuspze] Bar code keys

Create a lock with a bar code reader / camera which unlocks when presented with the correct bar code.

The interesting feature is that the key can easily be duplicated without needing special equipment like a key cutter or magstripe writer or RFID chip programmer.  Obviously, there is a security tradeoff, but is this feature useful?  Perhaps the authorities are monitoring or controlling access to all such special equipment for duplicating other types of keys.

A barcode on a sheet of paper has much less mass and volume than a metal key or magstripe card or RFID fob.  A smartphone can carry many barcodes.  If a smartphone is to be used, we could design a system in which the unlock code changes every time; old codes cannot be reused.  (Perhaps use a Bloom filter in the lock to store already seen keys.)

Programming the lock could also be done through the lock's camera barcode interface.  We begin to want a communication channel from the lock back to the phone.