Passwords in Peer-to-Peer

One of the differences between typical peer-to-peer (P2P) and client-server systems is the existence of user accounts. While many P2P applications, like public file sharing, are anonymous, more complex services such as decentralized online social networks require user authentication. In these, the common approach to P2P authentication builds on the possession of cryptographic keys. A drawback with that approach is usability when users access the system from multiple devices, an increasingly common scenario. In this work, we present a scheme to support logins based on users knowing a username-password pair. We use passwords, as they are the most common authentication mechanism in services on the Internet today, ensuring strong user familiarity. In addition to password logins, we also present supporting protocols to provide functionality related to password logins, such as resetting a forgotten password via e-mail or security questions. Together, these allow P2P systems to emulate centralized password logins. The results of our performance evaluation indicate that incurred delays are well within acceptable bounds.