An Efficient Encryption Algorithm for P2P Networks Robust Against Man-in-the-Middle Adversary

Peer-to-peer (P2P) networks have become popular as a new paradigm for information exchange and are being used in many applications such as file sharing, distributed computing, video conference, VoIP, radio and TV broadcasting. This popularity comes with security implications and vulnerabilities that need to be addressed. Especially, due to direct communication between two end nodes in P2P networks, these networks are potentially vulnerable to “Man-in-the-Middle” attacks. In this paper, we propose a new public-key cryptosystem for P2P networks that is robust against Man-in-the-Middle adversary. This cryptosystem is based on RSA and knapsack problems. Our precoding-based algorithm uses knapsack problem to perform a permutation and pads random data to the message. We show that comparing to other proposed cryptosystems, our algorithm is more efficient and it is fully secure against an active adversary.