Applying a cryptographic scheme in the RPINA protocol

The Respect Private Information of Non Abusers (RPINA) protocol allows users to communicate anonymously while the corresponding server ensures that the identity of the user will be revealed by a third party, called Directory Service (DS), should the user attempt a malicious attack. However, malicious co-operation between the server and the DS is the major vulnerability of the RPINA protocol. In this paper we introduce a technique, which decrease this vulnerability.