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Transcript By: Bryan Bishop

Tags: Consensus

Category: Conference

Streamlet: Textbook Streamlined Blockchain Protocols

Benjamin Chan


((…. stream went offline in the other room, had to catch up.))

Show you new consensus protocol called streamlet. We think it is remarkably simple intuitive. This is quite a bold claim, hopefully the protocol will speak for itself

Incredibly subtle, hard to implement in practice. We want to take this reputation and sweep it out the door.

Jump right in. First model the consensus problem. Motivating simplicity as a goal. Spend the bulk of talk, line by line through the protocol By the end, you will be able to understand it and describe it.

Never have I ever been able to understand a consensus protocol in 30 minutes, I hope we will get there.

Consensus Fundamental algorithm question people solve How do we get agreement A version of this problem

Reach agreement on sequence.

We have a set of processes. Very much in the permission setting. Aren’t blockchains my def permissionless. Proof of stake.

Modern protocols

Permission consensus relevant to blockchain research today

Problem statement

First consistency Everyone wants to see the same chain

Everyone wants to see the same chain.

Introducing adversaris Some subset of users are malicious.

On top of that network might be flaky.

On example what if someone

Difficult to achieve.

We don’t know which side is malicious.

Difficulty in solving.

Can we eliminate subtle voting rules that seem to be inherent to every consensus protocol.

Motivating simpler consensus protocol.

Goal simplest possible easy to understand consensus protocol.



Epochs Processes have local clocks, and run in synchronized epochs of 1 set of epochs.

2nd assumption Every epoch has a leader, a single leader known by all.

Definitions before meat of the protocol.

Block Notarized block Piece of the blockchain where all of the blocks are notarized

The streamlet protocol In every epoch… Leader- creates a new block Leader choose longest notarized chain Voters- signs the first block they see from the correct leader from the epoch they are in If and only if it extends the longest chain.

… Really, really simple. This is the meat of the finalization. This is our entire protocol. A leader proposes a block, extends the longest chain, then a voter votes on the block if it is indeed on the longest chain. Once he sees a few in a row, then he can finalize the entire chain. That’s it.

Sponsorship: These transcripts are sponsored by Blockchain Commons.

Disclaimer: These are unpaid transcriptions, performed in real-time and in-person during the actual source presentation. Due to personal time constraints they are usually not reviewed against the source material once published. Errors are possible. If the original author/speaker or anyone else finds errors of substance, please email me at kanzure@gmail.com for corrections or contribute online via github/git. I sometimes add annotations to the transcription text. These will always be denoted by a standard editor’s note in parenthesis brackets ((like this)), or in a numbered footnote. I welcome feedback and discussion of these as well.

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