1. A method for authenticating a party to a transaction, the method comprising: receiving a packet having at least a part of layer 2 header information replaced with a unique bit string; examining at least a part of the unique bit string; comparing the at least a part of the unique bit string examined with stored information; and authenticating the party only if the at least a part of the unique bit string examined matches the stored information; wherein the at least a part of the unique bit string examined depends on a type of the transaction, the type being a type of financial transaction.