We present BEAT, a set of practical Byzantine fault-tolerant (BFT) protocols for completely asynchronous environments. BEAT is flexible, versatile, and extensible, consisting of five asynchronous BFT protocols that are designed to meet different goals (e.g., different performance metrics, different application scenarios). Due to modularity in its design, features of these protocols can be mixed to achieve even more meaningful trade-offs between functionality and performance for various applications. Through a 92-instance, five-continent deployment of BEAT on Amazon EC2, we show that BEAT is efficient: roughly, all our BEAT instances significantly outperform, in terms of both latency and throughput, HoneyBadgerBFT, the most efficient asynchronous BFT known.
Decentralized cryptocurrencies rely on participants to keep track of the state of the system in order to verify new transactions. As the number of users and transactions grows, this requirement becomes a significant burden, requiring users to download, verify, and store a large amount of data to participate.
Vault is a new cryptocurrency design based on Algorand that minimizes these storage and bootstrapping costs for participants. Vault’s design is based on Algorand’s proof-of-stake consensus protocol and uses several techniques to achieve its goals. First, Vault decouples the storage of recent transactions from the storage of account balances, which enables Vault to delete old account state. Second, Vault allows sharding state across participants in a way that preserves strong security guarantees. Finally, Vault introduces the notion of stamping certificates, which allow a new client to catch up securely and efficiently in a proof-of-stake system without having to verify every single block.
Experiments with a prototype implementation of Vault’s data structures show that Vault’s design reduces the bandwidth cost of joining the network as a full client by 99.7% compared to Bitcoin and 90.5% compared to Ethereum when downloading a ledger containing 500 million transactions.