American Express Travel Related Services Company, Inc.

Naresh Bhandari

Manish K Deliwala

John G McDonald

Ajay Babu Maddukuri

Curtis Watson

Various embodiments for sending a cryptogram to a point of sale terminal while disconnected from a network. In some embodiments, for example, a computing device that is configured to display a prompt for a selection of a transaction account. An encrypted session key is retrieved through a network in response to determining a number of session keys associated with the transaction account is below a threshold. The computing device is also configured to generate a session key based at least in part on decrypting the encrypted session key using an encryption key and establish a wireless connection with a point of sale terminal for a purchase. A cryptogram is generated from the session key based at least in part on the user device being disconnected from the network. The cryptogram is sent to the point of sale terminal.

Sending a cryptogram to a POS while disconnected from a network

A system is configured for detecting a point of sale, receiving a personal identification number (PIN), generating a PIN based key using a message digest of the PIN, decrypting a data encryption key (DEK) using the PIN based key, and generating a DEK based dynamic key using the PIN based key. The system may also decrypt a session key using the DEK based dynamic key, generate a cryptogram from the session key, and send the cryptogram to the point of sale.

Growing community of inventors

Phoenix, AZ, United States of America

Naresh Bhandari