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Trifecta: Solving the Blockchain Trilemma

Sreeram Kannan


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.


Sreeram Kannan Headshot
Sreeram Kannan
University of Washington
Virtual Zoom Lecture
21 Apr 2020, 10:30am until 11:30am