Patent ID: 11968191
Assignee: AMERICAN EXPRESS TRAVEL RELATED SERVICES COMPANY, INC.
Field: Digital communication (Electrical engineering)
Classification: CPC H  G | IPC G  H

Claim 14:
15. A non-transitory, computer-readable medium, comprising machine-readable instructions that, when executed by a processor of a computing device, cause the computing device to at least:
retrieve an encrypted session key through a network in response to (i) determining a stored session key associated with a transaction account is set to expire in a threshold time period or (ii) detecting a number of session keys stored in the computing device is below a threshold;
establish a wireless connection with a point of sale terminal for a purchase;
generate a cryptogram from a decrypted session key based at least in part on the computing device being disconnected from the network, the cryptogram being generated by:
generating a dynamic key based at least in part on a data encryption key;
decrypting a token using the dynamic key;
generating an operator value by applying an operator to the token and a random number; and
generating the decrypted session key by decrypting the encrypted session key using the dynamic key; and
generating the cryptogram based at least in part on an encryption of the operator value using the decrypted session key; and

send the cryptogram to the point of sale terminal, wherein the cryptogram is used to authorize the purchase through the wireless connection between the computing device and the point of sale terminal.