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From: douglas@ddsw1.mcs.com (Douglas Mason)
Newsgroups: comp.dcom.telecom
Subject: Re: Phone Credit Cards
Message-ID: <3662@accuvax.nwu.edu>
Date: 8 Feb 90 21:19:25 GMT
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Reply-To: douglas@ddsw1.MCS.COM (Douglas Mason)
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X-Telecom-Digest: Volume 10, Issue 87, message 7 of 13


In article <3532@accuvax.nwu.edu> dave%westmark@uunet.uu.net (Dave Levenson) 
writes:

>Note: Bank ATM cards, like telco cards, _do_ have your PIN
>magnetically encoded on the card.  It is nice of the banks, however,
>to have thought of not printing it in a human-readable place on the
>card.

Actually, my understanding is that ATM cards do NOT contain the pin
number on it for obvious reasons.

I'm not concrete on this because I can't cite my source offhand, but
it seems to me that the ATM user enters the PIN number, which is sent
downline (encrypted) and a binary (1/0) response is sent back as to if
it was correct or not.  The system never sends downline anything to
the effect of "The PIN number is NOT xxxx, it is yyyy".

One of the reasons I belive this is that when I use my American
Express card in the bank machines, or my Citibank Visa, I can enter a
PIN number that was set by me LONG after I had the cards in my
possession.  ie: there was no way that they could have encoded the pin
number I selected BEFORE I received the cards!

Again, I can't really justify this, but it seems logical...


Douglas T. Mason | douglas@ddsw1.UUCP or dtmason@m-net |