A list of great resources on p2p things. The content here is curated by me, @mafintosh but please open PRs with suggestions.

Existing systems that I really like for the simplicity and ingenuity

• BitTorrent - no nonsense specification. Easy to read and implement
• PPSP - one of the papers that has inspired me the most in terms of making a modern file sharing network
• Scuttlebutt replication - Simple/efficient way of replicating append-only logs

Ways of securing / verifying data when receiving it from untrusted peers

• Dominic Tarr on asymmetric crypto
• Dominic Tarr on hashes

In a distributed system finding other peers interested in the same topic as you is usually an important step.

• Kademlia. Probably the simplest DHT out and a very well written paper. Use the key value store to point p2p key -> ip:port for discovery

How to connect to other peers

• ZeroTier blog post about hole punching