Patent Document ID: 7490246
Application ID: 11468500
Patent Flag: 1

Claim One:
1. A method of detecting unauthorized use of a device comprising: providing an initial input key for a device, the input key being a key for an encryption algorithm; encrypting data items to be communicated between the device and the server using the encryption algorithm and the input key, wherein the input key for the encryption algorithm is updated for every data item encrypted; communicating the encrypted data items from the device to the server; at the end of the communication, storing the last used input key in a persistent store in the device and the server; at a next communication using an iteration of the stored input key; comparing the iteration of the stored input key in the persistent store of the device to an expected input key determined based on a stored input key in the persistent store of the server; and blocking a communication between the device and the server if the iteration of the stored input key does not match the expected input key.