Algorand: A secure and efficient distributed ledger

• Published in: Theoretical computer science Vol. 777; pp. 155 - 183
• Main Authors: Chen, Jing, Micali, Silvio
• Format: Journal Article
• Language: English
• Published: Elsevier B.V 19.07.2019
• Subjects: Blockchain; Byzantine agreement; Cryptographic self-selection; Distributed computation; Permissionless system; Public ledger; Public ledger; Distributed computation; Byzantine agreement; Cryptographic self-selection; Permissionless system; Blockchain
• ISSN: 0304-3975; 1879-2294
• DOI: 10.1016/j.tcs.2019.02.001

A distributed ledger is a tamperproof sequence of data that can be publicly accessed and augmented by everyone, without being maintained by a centralized party. Distributed ledgers stand to revolutionize the way a modern society operates. They can secure all kinds of traditional transactions, such as payments, asset transfers and titles, in the exact order in which the transactions occur; and enable totally new transactions, such as cryptocurrencies and smart contracts. They can remove intermediaries and usher in a new paradigm for trust. As currently implemented, however, distributed ledgers scale poorly and cannot achieve their enormous potential. In this paper we propose Algorand, an alternative, secure and efficient distributed ledger. Algorand is permissionless and works in a highly asynchronous environment. Unlike prior implementations of distributed ledgers based on “proof of work,” Algorand dispenses with “miners” and requires only a negligible amount of computation. Moreover, its transaction history “forks” only with negligible probability: that is, Algorand guarantees the finality of a transaction the moment the transaction enters the ledger.