TY - CONF AB - While showing great promise, Bitcoin requires users to wait tens of minutes for transactions to commit, and even then, offering only probabilistic guarantees. This paper introduces ByzCoin, a novel Byzantine consensus protocol that leverages scalable collective signing to commit Bitcoin transactions irreversibly within seconds. ByzCoin achieves Byzantine consensus while preserving Bitcoin’s open membership by dynamically forming hash power-proportionate consensus groups that represent recently-successful block miners. ByzCoin employs communication trees to optimize transaction commitment and verification under normal operation while guaranteeing safety and liveness under Byzantine faults, up to a near-optimal tolerance of f faulty group members among 3f + 2 total. ByzCoin mitigates double spending and selfish mining attacks by producing collectively signed transaction blocks within one minute of transaction submission. Tree-structured communication further reduces this latency to less than 30 seconds. Due to these optimizations, ByzCoin achieves a throughput higher than Paypal currently handles, with a confirmation latency of 15-20 seconds. AU - Kokoris Kogias, Eleftherios AU - Jovanovic, Philipp AU - Gailly, Nicolas AU - Khoffi, Ismail AU - Gasser, Linus AU - Ford, Bryan ID - 8302 SN - 9781931971324 T2 - Proceedings of the 25th USENIX Conference on Security Symposium TI - Enhancing bitcoin security and performance with strong consistency via collective signing ER -