A method to increase the security & variety of one's PINs. On the back of each card, write down a random PIN. This is the fake PIN. Next, choose a decoder PIN. This PIN, when added or subtracted to the fake PIN, yields the actual PIN for the card. For half-baked security, use the same decoder PIN for all cards; for fully-baked security, use a different decoder PIN for each card, based on a certain arrangement of the numbers and/or letters printed on the card. This method allows you to have a different PIN for each card (more secure) whilst always enabling one to recall the PIN (ease of use). It has the added benefit of making it easier for you to forget the actual PIN, thus making it more difficult to reveal the PIN inadvertently (say, when shouting out involuntarily during a nightmare).
-- JacquesDemien, Jul 05 2003

How PINs already work http://www.totse.co...p_offs/atminfo.html
Some ATM PIN schemes actually do internally use offsets like this. [koshua, Oct 04 2004]

now why couldn't I have thought of that.
-- po, Jul 05 2003


Alternatively, choose an easily rememberable number - e.g. 1976

Your PIN number is the first, ninth, seventh and sixth digit of the credit card number.

Card: 4156 5689 4888 4719
V
Mnemonic" 1976
V
PIN: 4486
-- FloridaManatee, Jul 05 2003


To avoid camera capture of your pin, place three fingers on the row of buttons for each number. if your PIN is 1976, all the camera picks up is:

123 - 789 - 789 - 456

This narrows it down to 81 possibilities for the thief, hopefully not enough to make it worth his while...

I do this when entering my calling card number at a pay phone, which increases the possible numbers to 3^14...
-- dbsousa, Jul 05 2003


just before entering your number, you point to the sky and say - "wow, look at that"
-- po, Jul 05 2003


just before you take your money, the thief points to the sky and says - "wow, look at that"
-- FarmerJohn, Jul 05 2003


Thanks for the card number FlordiaManatee. Now, what's that expiration date?
-- Sarcophagus, Jul 09 2003


Of last year.
-- RayfordSteele, Jul 09 2003


Sarcophagus: I find it ironic that someone with your name would be concerned with dates of expiry.
-- JacquesDemien, Jul 09 2003


JacquesDemian: That's not irony, that’s coincidence... irony would be someone with a French moniker misusing a French term in an attempt to discredit an incredible request.
-- Sarcophagus, Jul 09 2003


This will allow a thief to have a chance at decoding your pin, even if they only get three tries, it still gives them a chance. The algorithm should not be too simple rather exceptionally complicated, and then you can write the formula itself on the card.
-- Trodden, Jul 10 2003


Sarc-I am now dumbfounded. Or is it crestfallen?
-- JacquesDemien, Jul 11 2003


Baked! I posted a very similar idea in 2002, in an annotation to "Panic PIN" topic.

"As far as remembering PIN's, a use a little trick. I write the PIN on the back of the card, after subtracting a "secret number" from it. I use the same secret number for all of my cards. For example, if my secret number was 101, and my PIN was 4352, I would write 4251 on the back of the card. Then, whenever I use the card, I just look at the number on the back and add 101 to it. Now I only have one number to remember!! --- JohnnyOnTheSpot, Oct 05 2002 "
-- JohnnyOnTheSpot, Jul 11 2003


I think algorthims are too confusing. Especially late at night.
-- croissantz, Aug 21 2004


What about making pins just a little bit longer and going alpha numeric? We can all remember our phone numbers (10 digits), our mobile (cell) numbers (11 digits), our names (6+ letters) so what about having a mix, say 10 characters long, which would give us 36^10 permutations... should be more than enough to confound the over-the- shoulder gawper. (Even 5 characters gives us 36^5 = 60.4 million choices).
-- artboy, Nov 02 2004



random, halfbakery