Distributed Computing Column 70: Formalizing and Implementing Distributed Ledger Objects

Blockchains and distributed ledgers, the technologies underlying Bitcoin and other decentralized transaction systems, have been garnering increasing interest in the theoretical distributed comput- ing community. The current column, by Antonio Fernández Anta, Chryssis Georgiou, Kishori Konwar, and Nicolas Nicolaou, starts with an informative overview of the world of distributed ledgers and motivates the need for rigorous approaches. The authors present an approach for formally specifying a distributed ledger in the context of several popular consistency conditions. The authors then give algorithms that implement the di erent variants in message-passing systems subject to crash failures. The article closes with a discussion of intriguing open questions. Many thanks to Antonio, Chryssis, Kishori and Nicolas for their timely contribution!