Years into the controversy around how to scale Bitcoin, there have been many challengers to Bitcoin core’s dominance. After XT, Classic and others have faded, Bitcoin Unlimited has been gaining traction and emerged as plausible new way forward. Bitcoin Unlimited wants to make the block size a parameter that is set by miners and nodes, but not fixed at a network level. They argue a natural fee market would emerge, allowing Bitcoin to rapidly scale and realizing its promise of electronic cash as well as store of value. The project is also member-driven, with democratic decisions driving its development decisions. Core developer G. Andrew Stone and Bitcoin Unlimited President Andrew Clifford joined us for the episode. Topics covered in this episode: How Stone and Clifford first got involved in Bitcoin The history of the blocksize debate and Bitcoin core alternatives Why the Bitcoin block size should be determined by miners not developers The natural fee market that would arise controlling the size of Unlimited blocks How the non-profit organization behind Bitcoin Unlimited works How a transition to Bitcoin Unlimited could look like Episode links: Peter Rizun: How Bitcoin Unlimited deals with large blocks Bitcoin Unlimited Website G. Andrew Stone: Examining Effect of Single Transaction Blocks on Network Peter Rizun: A Transaction Fee Market Exists Without a Block Size Bitcoin Unlimited Member Forum Bitcoin Network Hashrate Distribution This episode is hosted by Brian Fabian Crain and Meher Roy. Show notes and listening options: epicenter.tv/166

Ari Juels, a Professor at Cornell Tech (Jacobs Institute) and former Chief Scientist of RSA, joins us to discuss his work two of his blockchain-related research topics: Authenticated Data Feeds for Smart Contracts and criminal smart contracts. One of the shortcomings of decentralized smart contracts is their inability to retrieve information from the outside world. Smart contracts can’t make API calls to websites and data feeds, but rely on oracles to feed real-world information to the chain. This potentially requires a high trust in the oracle operators. Authenticated data feeds promise to solve the problem by relying on Intel’s novel SGX hardware. We also talked about how criminals could use smart contracts to more efficiently conduct crimes such as incentivizing the theft of private keys or even soliciting real-world crimes such as murder. Topics covered in this episode: Ari’s background in cryptography and cryptocurrencies The pain points with oracles as we describe them today The idea behind Authenticated Data Feeds The hardware and software architecture of the Authenticated Data Feed model and how hardware isolation works How Authenticated Data Feeds could be used to create criminal smart contracts The differents ways in which criminals could use Authenticated Data Feeds to release bounties for crimes such as private key theft or even murder Countermeasures to fight criminal smart contracts The Initiative For Cryptocurrencies & Contracts (IC3) and its raison d’être Episode links: Ari Juels' website Town Crier: An Authenticated Data Feed for Smart Contracts (white paper) The Ring of Gyges: Investigating the Future of Criminal Smart Contracts (white paper) IC3 - The Initiative For Cryptocurrencies & Contracts CCS 2016: Criminal Smart Contracts Talk Zero Days: Stuxnet Documentary This episode is hosted by Brian Fabian Crain and Sébastien Couture. Show notes and listening options: epicenter.tv/164