Patent ID: 8769290

Claim:
A system comprising one or more computers configured to perform operations comprising: receiving a first request from a client device; generating a user request token, including: creating a first data structure instance according to a protocol for creating structured and extensible data structures, the first data structure instance containing first data; serializing the first data structure instance; encrypting the serialized first data structure instance; creating a second data structure instance according to the protocol, the second data structure instance containing the encrypted and serialized first data structure instance; and serializing the second data structure instance to generate the user request token; sending a plurality of responsive items to the client device in response to the first request; sending the user request token to the client device; and receiving the user request token from the client device and recovering the first data in the user request token, including: receiving, with the user request token, a second request for additional information regarding one of the responsive items; and determining whether to respond to the second request based on the user request token.