At 11:05 PM 1999-03-02 -0600, Marshall Ruskin wrote:
>This November, I had lost the keys to my gas cap. I took my car to a
>locksmith. What followed completely amazed me.
>...
>He examined the key, took out a file from his pocket, and proceeded to a
>file a perfect working key from the blank.

Interestingly enough, my fianc�e just had someone do this in front of her
last weekend, and was just as shocked. (The car in question was a BMW.)

It's not necessarily a coating on the blank. When I was younger I studied
locksmithing from a friend who had a home study course. A good locksmith
can do it from the minute scratches that appear on the blank after a little
wiggling. It's an iterative process, but not a particularly onerous one.

It's even worse with the American cars. I've seen a little rubber "key" that 
one wiggles a few times, and opens almost any of certain vendors' locks
right up. 

The more I learn about locks, the more I appreciate how much society
operates on trust.