ALPS: Authenticating Live Peer-to-Peer Streams

Live streaming is one among many applications where data is continuously created and has to be quickly distributed among a large number of users. The peer-to-peer paradigm is thereby attracting interest with the prospect of overcoming scalability issues of more centralized approaches. Since data blocks travel along multiple (possibly malicious) peers, authenticating the origin of blocks becomes of prime importance to guarantee safety and reliability. The asymmetry of a single source and an arbitrary number of untrusted receivers requires the use of digital signatures and public key cryptography in general. This paper proposes a new signature scheme for broadcast authentication tailored towards peer-to-peer systems to overcome limitations of traditional approaches based on signature schemes like RSA and DSA, most notably in terms of delays, signature size, and computational complexity. It may further be of practical interest for other real-time application such as massive multiplayer peer-topeer gaming.