# Does Bitcoin Solve Byzantine Consensus?

DevFeed: [Does Bitcoin Solve Byzantine Consensus?](<https://devfeed.tech/articles/does-bitcoin-solve-byzantine-consensus-12470.md>)

Original publisher: [Read original article](<http://brooker.co.za/blog/2015/02/28/bitcoin.html>)

Author: Marc Brooker

Published: 2015-02-28T00:00:00Z

Content type: article

Language: en

Sources: [Marc Brooker's Blog](<https://devfeed.tech/sources/marc-brooker-s-blog.md>), [Marc Brooker's Blog](<https://devfeed.tech/sources/marc-brooker-s-blog-2.md>)

Topics: [Bitcoin](<https://devfeed.tech/topics/bitcoin.md>), [Blockchain](<https://devfeed.tech/topics/blockchain.md>), [distributed-systems](<https://devfeed.tech/topics/distributed-systems.md>), [Protocol (disambiguation)](<https://devfeed.tech/topics/protocol.md>), [cpu](<https://devfeed.tech/topics/cpu.md>), [DDoS](<https://devfeed.tech/topics/ddos.md>)

Tags: [analysis](<https://devfeed.tech/tags/analysis.md>), [bitcoin](<https://devfeed.tech/tags/bitcoin.md>), [blockchain](<https://devfeed.tech/tags/blockchain.md>), [distributed-systems](<https://devfeed.tech/tags/distributed-systems.md>), [publication](<https://devfeed.tech/tags/publication.md>), [research](<https://devfeed.tech/tags/research.md>), [technology](<https://devfeed.tech/tags/technology.md>)

## AI overview

The article examines research on whether Bitcoin solves Byzantine consensus. It discusses the Bitcoin Backbone Protocol, the protocol's safety, liveness, validity, and chain quality properties, and the argument that Nakamoto's protocol does not fully solve Byzantine agreement.

## Source excerpt

Does Bitcoin Solve Byzantine Consensus? An Interesting New Publication on Bitcoin and Consensus. The Bitcoin community is a fascinating mixture of political idealists, technology enthusiasts, entrepreneurs, investors and others. One group that's increasingly prominent is distributed systems researchers, attracted to some of the interesting problems around Bitcoin and the blockchain. There's plenty of interesting work to come, but some valuable research has already been done. Much of this work focuses on the theoretical core of bitcoin, and shows real progress towards answering concerns about bitcoin's safety and liveness bounds. In The Bitcoin Backbone Protocol: Analysis and Applications, Garay, Kiayias and Leonardos write about the core of Bitcoin, which they call the backbone. The argument for the correctness of the core of bitcoin from Satoshi's original paper is far from fulfilling: The majority decision is represented by the longest chain, which has the greatest proof-of-work effort invested in it. If a majority of CPU power is controlled by honest nodes, the honest chain will grow the fastest and outpace any competing chains. Garay et. al. attack this core argument directly, and analyze the exact safety and liveness properties of the protocol. The contribution that's going to launch a million online arguments is that bitcoin does not solve the Byzantine agreement problem1: This is because in case the adversary finds a solution first, then every honest player will extend the adversary's solution and switch to the adversarial input hence abandoning the original input. and Nakamoto's protocol does not quite solve BA since it does not satisfy Validity with overwhelming probability. Their argument hinges on the validity property of Byzantine agreement (or, rather, strong validity 2), and showing that the chosen value may not be one of the inputs to an honest player. In their definition of Byzantine agreement, agreements are only valid if they pick the input of one