Formalizing GDOI group key management requirements in NPATRL

Although there is a substantial amount of work on formal requirements for two and three-party key distribution protocols, very little has been done on requirements for group protocols. However, since the latter have security requirements that can differ in important but subtle ways, we believe that a rigorous expression of these requirements can be useful in determining whether a given protocol can satisfy an application’s needs. In this paper we make a first step in providing a formal understanding of security requirements for group key distribution by using the NPATRL language, a temporal requirement specification language for use with the NRL Protocol Analyzer. We specify the requirements for GDOI, a protocol being proposed as an IETF standard, which we are formally specifying and verifying in cooperation with the MSec working group. 1