Abstract: A computer-readable medium embodies a computer program for obtaining information for a payment transaction. The computer program comprises computer-readable program code for: generating a first message including an identifier and a request for the information, sending the first message via a first communication path, receiving a second message including the information and the identifier via a second path different from the first communication path, and processing the payment transaction using the information obtained in the second message.

Abstract: A computer-readable medium embodies a computer program for authenticating a user. The computer program comprises computer-readable program code for: generating a first message including an identifier for a session, sending the first message through an interface associated with the session, receiving a response message including the identifier for the session, a user identifier, and at least a portion encrypted using a private key associated with a mobile device associated with the user, and authenticating the user in response to identifying that the response message includes at least the portion encrypted using the private key associated with the mobile device.

Abstract: A computer-readable medium embodies a computer program for registering a mobile device. The computer program comprises computer-readable program code for: generating a first message including a first code in response to receiving a request to register the mobile device for use with a future session with an entity, sending the first message including the first code, receiving a second message including the first code and at least a portion encrypted using a private key associated with the mobile device, and registering the mobile device for use with the future session based on at least the portion of the second message being encrypted using the private key associated with the mobile device.