Methods, systems, and apparatus for verifying the identity of a cardholder are provided. A digital representation of a magnetic characteristic of a magnetic stripe of the card is stored on a portable electronic device of the cardholder. During a transaction, the digital signature is then transmitted so that it can be compared with a reference signature. The identity may be verified, and a response sent to a party requesting the verification, e.g., during a transaction between the requesting party and the verified party.