Authenticated Secure Group Communication using Broadcast Encryption Key Computation

Broadcast Encryption deals with broadcasting an encrypted message, so that only a set of users termed privileged can decrypt it. This is made possible with the computation of a secret key which is known only to members of the privileged set. This privileged set can be called as a secure group and the communication within the set as Secure Group Communication which provides only confidentiality. Providing authentication for the messages exchanged between group members in addition to confidentiality is an important issue in Secure Group Communication. We develop a protocol for Secure Authentic Communication where we address authentication for the scheme proposed by Fiat-Naor Broadcast encryption. Authentication scheme used is a multiparty authentication scheme which allows all the users in the system to send and receive messages simultaneously. Our scheme is secure against colluding malicious parties numbering fewer than k. The scheme provides authenticity by using a part of the information keys which is used for secret key computation, thus, without increasing the storage at the user.