While blockchain protocols such as Bitcoin have shown how to secure a ledger in a purely decentralized setup, they are not scalable. Unsuccessful attempts at scalability have led to a folk theorem termed the Blockchain Trilemma, which states that no blockchain achieves all three properties: security, decentralization and scalability. We disprove this folk theorem by proposing Trifecta, a blockchain protocol that achieves all 3 properties.
Trifecta is (1) truly decentralized, with constant amount of compute, storage and communication resources per node; (2) proven secure against fully adaptive adversaries and (3) total throughput scaling near-linearly with the number of network nodes. This requires a brand new blockchain design with several new components: (a) a new proof-of-work protocol (Prism), (b) its proof-of-stake adaptation, (c) a new data-availability oracle (Coded Merkle Tree), and (d) a self-allocation engine. We highlight how ideas from information theory (typicality), coding theory (list decoding), large deviations of branching random walks and dynamic game theory play a key role in solving this problem. The talk will assume no prior background in blockchain.
Sreeram Kannan is currently an assistant professor at University of Washington, Seattle. He was a postdoctoral scholar at University of California, Berkeley between 2012-2014 before which he received his Ph.D. in Electrical Engineering and M.S. in mathematics from the University of Illinois Urbana Champaign. He is a recipient of the 2019 UW ECE outstanding teaching award, 2017 NSF Faculty Early CAREER award, the 2013 Van Valkenburg outstanding dissertation award from UIUC, a co-recipient of the 2010 Qualcomm Cognitive Radio Contest first prize, a recipient of 2010 Qualcomm (CTO) Roberto Padovani outstanding intern award, a recipient of the SVC Aiya medal from the Indian Institute of Science, 2008, and a co-recipient of Intel India Student Research Contest first prize, 2006. His research interests include the applications of information theory and learning to blockchains, computational biology and wireless networks.