ECC Based Dynamic Multiparty Key Agreement

Multiparty key agreement (MKA) is a secure and robust approach to establish a group key forsecure group oriented applications over non-private underlying networks, and it can be effciently implementedwith ECC (Elliptic curve cryptography). In this paper, wepropose a generic two round model for ECC based MKA.All users involved are organized into a ring in this modeland distributedly compute a group key by two round message exchanges. Upon this model, we construct a concrete ECC based MKA protocol with scalability and lowcomputational complexity. The protocol is dynamic, thatis, it supports key update when user group membershipchanges to ensure forward secrecy and backward secrecy.The protocol is proved to be secure under the DecisionDiffe-Hellman (DDH) assumption on the elliptic curve.Its security is reduced to the intractable DDH problem onthe elliptic curve.