Patent ID: 8107627

Claim:
A security system for protecting source information from being illicitly copied from a remote location, the security system comprising: a processor and an access device configured to execute a challenge-response protocol between them, during which protocol a secret key is exchanged; a timer configured to measure a time-lag between a challenge and a response, where said challenge is sent from said processor to said access device during said challenge-response protocol and said response is received from said access device at said processor; and a verifier configured to cause the protocol to be aborted if the measured time-lag is greater than an expected time-lag between said challenge and response during said challenge-response protocol and, wherein said verifier is configured to continually request randomly selected portions of said source information to be protected, in more than one of a plurality of predetermined order sequences until the verifier is able to determine statistically whether the access device accessing said source information in response to said verifier request is local or remote.