Quadrille - 9:46 am on Sep 12, 2008 (gmt 0)

Not quite:

"If you have a lock on your house a thief will become a lock pick, the better the lock, the better a lock pick the thief becomes - until such time as another house becomes easier."

It's exactly like putting on running shoes when two of you are pursued by a bear - you don't need to outrun the bear.

Security needn't be about the 'safest', for most purposes, just 'safer than most'.

CAPTCHA can never defeat human slaves alone (it was designed specifically to let humans pass!); but as one line of defense, it can delay the break; language based tests can defeat the cheapest clickers - they don't speak English.

And as the lock pickers advance, so must the locksmiths. And they do. ;)