A Mechanized Logic for Secure Key Escrow Protocol Verification

Reasoning about key escrow protocols has increasingly become an important issue. The Escrowed Encryption Standard (EES) has been proposed as a US government standard for the encryption of un-classiied telecommunications. One unique feature of this system is key escrow. The purpose of key escrow is to allow government access to session keys shared by EES devices. We develop a framework to formally specify and verify the correctness of key escrow protocols that we mechanize within the HOL theorem proving system. Our logic closely follows the logic, SVO , used for analyzing cryptographic protocols which was developed by Syverson and vanOorschot 13]. Using the HOL mechanization of SVO , we formally demonstrate the failure of the EES key escrow system by showing that it does not insure that the escrow agent receives correct information. This was previously shown experimentally 2]. Last, we ooer an alternative escrow protocol and demonstrate its correctness.