• introduction

    This is my attempt to list all possible blockchain consensus out there, I welcome pull request of the blockchain community! let's make it the main reference for blockchain consensus. Visit also to keep track of new developments in the distributed ledger technology space.

    Blockchain Consensus?

    At the core of the Blockchain disruption is a consensus algorithm:

    Consensus algorithms enable network participants to agree on the contents of a blockchain in a distributed and trust-less manner.

    “Consensus decision-making is a group decision-making process in which group members develop, and agree to support a decision in the best interest of the whole. Consensus may be defined professionally as an acceptable resolution, one that can be supported, even if not the “favourite” of each individual. Consensus is defined by Merriam-Webster as, first, general agreement, and second, group solidarity of belief or sentiment.” Wikipedia

    And the consensus algorithm plays a crucial role in maintaining the safety and efficiency of the blockchain. Using the right algorithm may bring a significant increase to the performance of blockchain application.

    The trilemma claims that blockchain systems can only at most have two of the following three properties:

    1. Decentralization (defined as the system being able to run in a scenario where each participant only has access to O(c) resources, i.e. a regular laptop or small VPS)
    2. Scalability (defined as being able to process O(n) > O(c) transactions)
    3. Security (defined as being secure against attackers with up to O(n) resources)

    Each consensus algorithm has its own application scenario. There is no absolute good or bad. The choice of which consensus to use for implementing the blockchain depends on the type of network and data.

    For a transaction to be valid on most cryptocurrency networks, the transaction needs to collect a certain number of confirmations (often equals to an inclusion in a block of a blockchain) from the network. E.g 10 confirmations mean to see a specific transaction in one block and 9 consecutive blocks.

    Visit now 

  • Tezos was created first and foremost to address a governance issue in decentralized cryptographic ledgers. It does so by allowing stakeholders to approve updates to the protocol, including the consensus algorithm, and the governance rule themselves. Tezos is written in OCaml (a functional programming language) and rely on Coq for advanced proof checking and formal verification. Source code will be opened and available later this year.

    Arthur Breitman of "Tezos" gave this presentation on this new technology on Wednesday, August 31st at Monetas HQ (Zug – Switzerland)

  • Recorded by me at Tech Tuesday Meetup group 4 Oct. 2016

    "Blockchain, cryptography, and consensus" By Christian Cachin (Cryptographer, IBM Research - Zurich)

    Christian Cachin is a senior researcher at IBM Research Zurich. His research focuses on information security and distributed systems, with emphasis on secure protocols for distributed systems. Two of his current research topics are blockchain and consensus protocols in general. He received his PhD in cryptography from ETH Zurich in 1997.