Want to know my PIN?

I have a terrible memory. I must write everything down. PINs - how many of them do we have? There's the one for our current account, the one for our credit card, the one that opens the door to the office, the one ... um ... I don't remember, but I'm sure there's more. Disobeying the first rule of password protection, I had those PINs written down. In my defense, I used a Caesar Cypher, but that's about as strong a defense as saying, "the dog ate my homework."

Anyone with a couple of brain cells and about 10-minutes could've taken my note and emptied my bank account.

Want to know how my PIN is now written? OEPW.

Go ahead and break it. Okay, there are only a thousand possible combinations, but at least letters I've written down don't give you a clue. On the other hand, I can turn those letters back into digits in about 15-seconds.

How does it work?

Choose a word, or phrase with at least ten distinct letters. A poor example would be "ABCDEFGHIJ". A, slightly, better example would be "THE COMPLETE WORKS OF WILLIAM SHAKESPEARE".

Throw away the spaces and take the first ten distinct letters: "THECOMPL" plus "W" then "R".

Now assign the digits 0 to 9 to those first ten distinct letters. For each digit in the PIN simply replace with the letter assigned to that digit.

Not well explained? Okay, here's a worked example:

1) We choose a phrase with ten distinct letters ... um, how about, "CHOOSE A PHRASE WITH TEN DISTINCT LETTERS".

2) Throw away the spaces to get "CHOOSEAPHRASEWITHTENDISTINCTLETTERS".

3) Assign the digits 0 to 9 to the first ten distinct letters:
CHOOSEAPHRASEWITHTENDISTINCTLETTERS
012.3456.7...89

4) Replace the digits in the PIN with the assigned letters: a PIN of 2468 would become OEPW.

Oh yeah, when I said OEPW was my PIN ... well, you didn't think I was actually going to give you my PIN did you?