Patent ID: 8511547

Claim:
A method of generating authentication data for use in a transaction comprising: providing a contactless chip device associated with at least one authorized user having pre-stored secret data, configured to communicate with an unsecure mobile device; receiving a first input value into said mobile device; detecting said contactless chip device in proximity to said mobile device and thereafter beginning communication between said contactless chip device and said mobile device; communicating data derived from said first input value from said mobile device to said contactless chip device; receiving a dynamic value derived from said first input value and said pre-stored secret data from said contactless chip device sufficient to validate the involvement in said transaction of said at least one authorized user at said mobile device without receiving said pre-stored secret data at said mobile device; after said communicating said dynamic value, detecting that said contactless chip device has been removed from being in proximity to said mobile device, thereby preventing further communication between said contactless chip device and said mobile device; and communicating authentication data based at least in part on said dynamic value to a user of said mobile device.