An Efficient Broadcast Encryption for Secure Group Communication

Abstract

Secure group communication systems typically rely on a group key, a secret shared by all members of the group. Confidentiality is provided by encrypting all messages with the group key. Meanwhile, some of the associated problems with securing group communications are rekeying when membership changes and multiple sub-group key storage by users. In this paper, an Efficient Broadcast Encryption Scheme (EBES) which uses key encapsulation mechanism was designed to eliminate these problems. Symmetric cryptosystem (AES 128), Elliptic Curve Cryptosystem in prime order Galois Field GFp simulated over the Elgammal Cryptosystem (EC-ELGAMAL) and the Chinese Remainder Theorem (CRT) are the major components of our solution. The design also introduced the concept of mutual authentication into group communications using cryptographic keys. The authentication was performed smoothly using the Elliptic Curve Digital Signature Scheme (ECDSS). The security of our solution was formally proven by reduction to the security of EC-ELGAMAL cryptosystem, which is based on Elliptic Curve Discrete Logarithm Problem (ECDLP). This paper is concluded with a set of experimental results that support our research.