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Re: One way column in a view

From: Malcolm Dew-Jones <>
Date: 14 Apr 2005 17:17:44 -0800
Message-ID: <>

Randy Harris (notvalid_at_no.spam) wrote:
: "Malcolm Dew-Jones" <> wrote in message
: > Randy Harris (notvalid_at_no.spam) wrote:
: > : Anyone know of a way that I can create a view that would prevent viewing
: a
: > : certain column but still permit that column to be used in the where
: clause?
: > : I need for users to be able to look up data by the credit card number,
: but
: > : not be able to get a list of credit card numbers.
: >
: > Of course they will still be able to run a series of independent lookups
: > of potential credit card numbers to find which are valid and build a list
: > that way.
: >
: >
: > --
: >
: > This space not for rent.

: With 16 digits on most credit cards the possible combinations would make
: that nearly impossible. Wouldn't it?

Good point, though there are fewer than 16 effective digits. The first one or two digits are codes that have very few values.

At least one digit is a check sum.

So only the remaining 14 digits would need to be checked.

Major cards like visa have many brands, which makes me suspect that the numbers are allocated in some kind of range, so that a knowledgable person could probably reduce the numbers that need to be examined even further.

Otherwise, the possible 14 digit numbers are everything less than 100,000,000,000,000 (a hundred trillion).

If there are 100 million credit cards then every 1,000,000 numbers is a card, so at one lookup every two seconds you could find 15 credit cards a year, if you could check ten per second you could find about 300 per year.

Obviously some numbers are guesses, but it certainly appears you're right, that doesn't seem like a big risk compared to other techniques someone might use to get information on credit card numbers.


This space not for rent.
Received on Thu Apr 14 2005 - 20:17:44 CDT

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