Sybil Defenses: Artificial Costs

This lecture covers Sybil defenses focusing on artificial costs and proof-of-work mechanisms, first used as anti-spam and popularized by Bitcoin. It also explores social/trust network defenses like the 'Web of Trust' model and assumptions in social graph scenarios. The concept of Proof of Personhood is introduced, aiming to link identity to being a physical person, with approaches such as pseudonym parties and co-located physical bodies. The lecture concludes with next steps involving reviewing Paxos and implementing it, along with recommended readings on Sybil attack detection and resistance.