Just read CRYPTO-GRAM, February 15, 2003. (A sometimes interesting newsletter.)

Code:
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And saw this article about a guy at AT&T Labs who applied an "oracle attack" to master-key-lock systems producing a master-key in minutes.
Is your door safe? :P

Code:
Blaze's home page for his research:
<http://www.crypto.com/masterkey.html>

The paper itself:
<http://www.crypto.com/papers/mk.pdf>

The reaction to the paper:
<http://www.crypto.com/papers/kiss.html>

News articles on the research:
<http://www.nytimes.com/2003/01/23/business/23LOCK.html>
<http://www.mail-archive.com/cryptography@wasabisystems.com/msg03415.html>

Previous web references to Blaze's technique:
<http://sethf.com/infothought/blog/archives/000164.html>

Jewel theft using the master key vulnerability:
<http://www.nbc4columbus.com/news/1921563/detail.html>
/Manko