Here's a tip I haven't seen yet other than the post concerning Belgium- don't do it. Get someone else to do it for you- this someone will namely have more experience and resources to do exactly you need to do. Large ISPs have such services and you'll want to call business services with the credit card companies on how to hire a good service. While it may be pricey, keep in mind it's better than worrying about the precious credit card numbers yourself.
in reply to Encrypting Credit card numbers
AgentM Systems nor Nasca Enterprises nor
Bone::Easy nor Macperl is responsible for the
comments made by
AgentM. Remember, you can build any logical system with NOR.