Streamlet: Textbook Streamlined Blockchains

Date: September 14, 10 AM – 11 AM AEST (September 13, 8 PM – 9 PM EST).


Title: Streamlet: Textbook Streamlined Blockchains

Guest Speaker: Professor Elaine Shi, Cornell University, Ithaca, New York, USA,

Elaine Shi is an Associate Professor in Cornell University. Her research interests include cryptography, distributed systems, foundations of blockchains, and language-based security. She is a recipient of the Packard Fellowship, the Sloan Fellowship, the ONR YIP award, the NSF CAREER award, the NSA Best Scientific Security paper, and various other best-paper and research awards. Elaine obtained her Ph.D. from Carnegie Mellon University. Before joining Cornell, she was an Assistant Professor in UMD.

Abstract: Numerous works in the past have focused on constructing simple and understandable distributed consensus protocols. In my talk, I will present an absurdly simple consensus protocol called Streamlet. The entire protocol is: every epoch, a leader proposes a block extending the longest chain it has seen so far. Everyone votes for (i.e., signs) the first block proposed by the leader if it extends from one of the longest notarized chains they have seen so far. When a block collects votes from 2/3 of the nodes, it becomes notarized. Notarized does not mean final. Finality is decided with the following rule: for any chain in which all blocks are notarized and moreover, the last three blocks have consecutive epoch numbers, the entire chain except the first block is final. Streamlet is inspired by the community’s past five years of work on consensus motivated by decentralized blockchains. To the best of our knowledge, it is the simplest embodiment known thus far, and it subsumes classical landmark protocols such as PBFT/Paxos and their numerous variants. It is a great fit for pedagogy.