a system and method for preventing unauthorized duplication of an identity module , im , and authenticating valid ims . different information is stored in the im and an authentication center , auc , and if the information in the auc is leaked , it is insufficient to clone the im . the im generates a first key , k1 , and a second key , k2 , while assuring that k1 cannot be derived from k2 , and optionally that k2 cannot be derived from k1 . the im exports k2 and an identifier to the auc while keeping k1 secret within the im . during authentication , the im provides to a third party such as a vlr , information containing the identifier . the vlr forwards the information to the auc , which retrieves k2 based on the identifier and generates a first value , r , and a second value , x , based on at least k2 . the auc then returns r and x to the vlr , which forwards r to the im . the im then generates a response , res , based on at least k1 and r , and sends the res to the vlr . the vlr then verifies the res based on x .