US Patent 7819322 Portable consumer device verification system

A method for verifying a portable consumer device. The method includes receiving an authorization request message associated with a transaction conducted using a portable consumer device. The portable consumer device includes a portable consumer device fingerprint. The authorization request message includes an altered portable consumer device fingerprint and an algorithm identifier. The method also includes selecting an algorithm from among a plurality of algorithms using the algorithm identifier, determining the portable consumer device fingerprint using selected algorithm and the altered portable consumer device fingerprint, determining if the portable consumer device fingerprint matches a stored portable consumer device fingerprint, and sending an authorization response message after determining if the portable consumer device fingerprint matches the stored portable consumer device fingerprint.