[Cryptography] French credit card has time-varying PIN

[John Levine]

>> And after they change, the previous three digits are essentially worthless, and that's a huge blow for criminals.
>
>... except this only works when you're talking about immediate transactions -- and I'd be very, very surprised if there weren't still a fair percentage of delayed transactions.

No, it just means that the transaction needs a time stamp so the bank
can tell what the CVV should have been.  I don't immediately see that
as a security problem unless you have a bank so dumb that it'll let
merchants do 500 transactions with timestamps two hours apart to try
and guess the CVV.

R's,
John