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The Taub Faculty of Computer Science Events and Talks

ceClub: Challenges in Blockchain Protocols
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Ittay Eyal (Cornell University)
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Wednesday, 23.12.2015, 11:30
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EE Meyer Building 861
The study of security in decentralized large-scale distributed systems has made a large leap forward with the introduction of cyber-currencies, starting with Bitcoin. This talk will discuss three results tackling central challenges that were exposed by this progress.

Cyber-currencies, as the name implies, implement secure and reliable digital currencies, but their promise has grown beyond currency, for example to so-called smart contracts and to digital asset infrastructure. Their success is mainly due to the introduction of Bitcoin's blockchain protocol, which achieves a variant of consensus, secured by a proof-of-work incentive mechanism.

I will show that the bound on the resilience of blockchain protocols is significantly worse than previously thought. This is due to the selfish mining attack, which is effective against all blockchain protocols known to date. Next, I'll show that security does not stand at odds with performance at the adversarial environments where blockchain algorithms live. I'll present a novel blockchain protocol that achieves both security and optimal performance, demonstrated in the largest blockchain lab-experiment to date. Finally, I'll address an issue that is general to the proof-of-work incentive mechanism, namely that participants tend to form coalitions, leading to centralization. I'll present a game-theoretic analysis of a novel attack among such coalitions, which leads to surprising consequences.

Ittay Eyal is a post-doctoral associate in Cornell university. His research focuses on the security and the performance of large-scale distributed systems, particularly cyber-currencies. He c