How about you generate a key using code to generate a random string and use that as the key. at that instant your script emails 1 the key lets say
peter@server1.com and the encrypted card# to
peter@server2.com using ssl to send the emails. that way the key changes each time a card is processed. you then download your emails (with ssl) from the 2 different mail servers and put them together with decryption script run on your local machine with a copy of PHPdev or something as a aweb server on local computer. That way if a hacker did happen to hack your script they would also have to hack 2 mail servers in time before you download your emails. and if you do that regularly would be fine. I know this means manual processing the cards at the end of the day but does everyone think this is a good idea if im willing to process manually at the end of the day
