Distributing Trust Amongst Multiple Authentication Servers12

Abstract

Some recent research on key distribution systems has focussed on analysing trust in authentication servers, and constructing key distribution protocols which operate using a number of authentication servers, a minority of them may be untrusted. This paper proposes a key distribution protocol with multiple authentication servers using a cross checksum scheme. In the protocol, multiple untrusted servers generate candidate session keys for two clients. The clients use the cross checksum scheme for the verification of these candidate keys. It is not necessary for the clients to trust an individual server. A minority of corrupted and colluding servers cannot compromise security, and their inappropriate behaviour can be detected. Comparing our protocol to similar proposals, we will consider the number of messages exchanged, the length of messages, and the method of key generation.