3-D Printed Skeleton Keys Can Pick High-Security Locks in Seconds

Some user re-keyable locks are supposedly resistant to bump attacks, like Schage's SecureKey. (What I use.)

Re-keyable locks are more expensive, but worth it.

If you do a patent search about rekeyable locks, you see that they are fairly recent. In 1967, a patent was granted on a lock that flips permanently from one combination to another. During construction, a builder uses the builder's key to access the property. This key stops working as soon as the owner uses the owner key to open the lock for the first time.

There is patent activity in this area as recently as 2009.

This site has some discussion of the Schlage SecureKey internals: http://www.lockwiki.com/index.php/Schlage_SecureKey

SecureKey is programmed by inserting the original Reset Key into the lock and turning into a special position (a 45 degree angle, IIRC). You can then remove the Reset Key, and insert the new key, which can have an arbitrary code. You turn that to the original position, and the lock is programmed. Internally, it looks like the lock "quantizes" the height of each cut to one of ten positions to memorize the new pattern; but it's all mechanical. Quite neat!