Abstract: One aspect of this disclosure relates to a method for improving the security of authentication for client information in a payment system. The payment system may be applicable for credit card transactions such as may occur over the Internet or other networks. This is done with a system in which some of the client information currently required is not readily ascertainable to operators within the payment authorization system. In another aspect, a certificate is provided for use in a payment system. The payment system identifies an unknown person by the use of a private key and a public key. The private key is secretly held and is used to digitally sign and authenticate a payment using the public key. The payment system identifies the owner of the public key by the presentation of the digital signature from the private key and the public key. The certificate is an immutable form of the public key and identifying information.