Take a moment and reach into your pocket, or wherever you keep your keys, and take a close look at your front door key. Unless you are a locksmith, a burglar, or a hacker you have probably never given that key much thought. You place the key in the lock, turn it, and the door opens!  Engineering at its most elegant and deceptive simplicity—it just plain works.

Hold the key so you can see the peaks and valleys. Reminiscent of an Alpine horizon, these notches are what enable the key to line up a set of tumblers inside the lock cylinder to make the lock turn. Now hold a similar key against the first key, and notice the different, apparently unique set of ridges and valleys. The length of the keys and the height of the ridges form a finite space, not an infinite one. This means that randomness is lost, and for every lock, there are probably one percent of keys in the general population that can open that lock. So if you live in a town of half a million people who all use a very popular lock, then 5,000 of your neighbors are carrying a key that can open your front door. This weakness in uniqueness has caused lock manufacturers to devise new, more secure locks that increase the random available patterns on keys.

Now, consider the password that you use on your computer and probably many of your favorite Web sites. Random? Unique? Lengthy? If you are like most of your Internet neighbors, then your password is very similar, if not exactly the same as theirs. In fact, Symantec recently stated that 91 percent of the passwords in use on the Internet are derived from a “dictionary” of no more than 1,000 words.

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Tags: keys, lock cylinder