On Sun, 2010-05-30 at 01:49 -0400, Paul M Foster wrote:

> This question is for people who take and store credit card information
> for customers.
> Credit card companies, in an attempt to lessen fraud, are tightening the
> screws on merchants who take credit cards. One aspect of this is a
> requirement to store credit card information from customers encrypted.
> So let's say you have a customer whose credit card you keep on file,
> because they'll be charging other items with you. The credit card
> companies would like you to store this information with strong
> encryption, which in their mind is one-way encryption.
> Now let's say that the credit card number is part of the customer
> record. When looking at the customer record, you see just the last four
> digits of the card. But when editing the record or when printing out
> reports of things which must be charged, you will see the whole number.
> Assume the users of the system have logins and passwords.
> Now if you one-way encrypt the credit card numbers in the customer
> records, then it seems to me that any time that field has to be accessed
> (to edit the record or charge something to the card), you'd have to have
> the user enter a specific "password" to unlock the encryption. This
> would be quite in addition to their username and password. Moreover for
> this to be as secure as the credit card companies would like it,
> whatever "password" is used would need to be changed frequently,
> particularly at any change of personnel. This means you'd have to
> re-encrypt all the credit card numbers using the new "password" every
> few months or when you fire someone who had access to the data.
> This seems like an excessively cumbersome solution. Is this seriously
> the way it's done? Does anyone have a better solution?
> Paul
> -- 
> Paul M. Foster

It's not just a matter of encrypting the credit card details. You also
have to ensure the server meets specific security requirements, every
last little bit of software has to be updated and patched. There are
services that will check your server out for you (last one I used was
McAffee Secure) I am certain that this is a legal requirement in order
to allow you to process credit card details.

You won't have to encrypt the password against the username of whoever
has access to it. Just encrypt it the once, and use the DBMS side of
things to manage access rights. Maybe use a couple of fields in the DB
to store the credit card number in two versions, one that is two-way
encrypted, the second that is one-way. You can set up your web system to
only have access to the one-way version, meaning that the actual number
can't be got by that user. The two-way encrypted version would be
accessible only by a specific second DB user, the access details of
which could change when personnel changes.


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