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Algorand: Scaling Byzantine Agreements for Cryptocurrencies

This paper introduces Algorand, a novel permissionless blockchain protocol designed to overcome the scalability, security, and decentralization challenges faced

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Abstract

This paper introduces Algorand, a novel permissionless blockchain protocol designed to overcome the scalability, security, and decentralization challenges faced by early cryptocurrencies. Algorand employs a pure Proof-of-Stake (PoS) approach to establish Byzantine Agreement, where users are secretly and randomly selected via a verifiable random function (VRF) – termed ‘cryptographic sortition’ – to form committees responsible for proposing and validating blocks. This committee-based consensus mechanism is designed to be highly efficient, offering instant transaction finality without requiring forks. The protocol achieves security under the assumption that a supermajority of the total stake is controlled by honest participants, even with a minority of honest online users. The paper details the mechanism for rapid committee re-selection per block, preventing malicious actors from corrupting a committee before it completes its task. Algorand’s design contributes significantly to the field of PoS consensus by introducing a robust and scalable solution that aims to balance security with performance. Authors: Yossi Gilad, Rotem Hemo, Silvio Micali, Georgios Vlachos, Nickolai Zeldovich Publication: Academic Paper Publication date: 2017-01-01

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Key findings

  • Algorand achieves a permissionless Byzantine Agreement through a pure Proof-of-Stake mechanism.
  • Committee members for block proposal and validation are secretly and randomly selected using cryptographic sortition.
  • The protocol offers instant transaction finality, eliminating the possibility of forks.
  • Security is maintained even if a supermajority of the total stake is malicious, provided a certain threshold of online users are honest.
  • The committee re-selection process is rapid, mitigating the risk of malicious takeover.

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Citation

Yossi Gilad, Rotem Hemo, Silvio Micali, Georgios Vlachos, Nickolai Zeldovich (2017). Algorand: Scaling Byzantine Agreements for Cryptocurrencies. Academic Paper. https://dl.acm.org/doi/pdf/10.1145/3132747.3132783
Canonical knowledge ID: research:algorand-scaling-byzantine-agreements-for-cryptocurrencies