We present simple and practical protocols for generating randomness as used by asynchronous total-order broadcast. The protocols are secure in a proof-of-stake setting with dynamically changing stake. They can be plugged into existing protocols for asynchronous total-order broadcast and will turn these into asynchronous total-order broadcast with dynamic stake. Our contribution relies on two important techniques. The paper "Random Oracles in Constantinople: Practical Asynchronous Byzantine Agreement using Cryptography" [Cachin, Kursawe, and Shoup, PODC 2000] has influenced the design of practical total-order broadcast through its use of threshold cryptography. However, it needs a setup protocol to be efficient. In a proof-of-stake setting with dynamic stake this setup would have to be continually recomputed, making the protocol impractical. The work "Asynchronous Byzantine Agreement with Subquadratic Communication" [Blum, Katz, Liu-Zhang, and Loss, TCC 2020] showed how to use an initial setup for broadcast to asymptotically efficiently generate sub-sequent setups. The protocol, however, resorted to fully homomorphic encryption and was therefore not practically efficient. We adopt their approach to the proof-of-stake setting with dynamic stake, apply it to the Constantinople paper, and remove the need for fully homomorphic encryption. This results in simple and practical proof-of-stake protocols.
@InProceedings{alpos_et_al:LIPIcs.AFT.2023.31, author = {Alpos, Orestis and Cachin, Christian and Kamp, Simon Holmgaard and Nielsen, Jesper Buus}, title = {{Practical Large-Scale Proof-Of-Stake Asynchronous Total-Order Broadcast}}, booktitle = {5th Conference on Advances in Financial Technologies (AFT 2023)}, pages = {31:1--31:22}, series = {Leibniz International Proceedings in Informatics (LIPIcs)}, ISBN = {978-3-95977-303-4}, ISSN = {1868-8969}, year = {2023}, volume = {282}, editor = {Bonneau, Joseph and Weinberg, S. Matthew}, publisher = {Schloss Dagstuhl -- Leibniz-Zentrum f{\"u}r Informatik}, address = {Dagstuhl, Germany}, URL = {https://drops.dagstuhl.de/entities/document/10.4230/LIPIcs.AFT.2023.31}, URN = {urn:nbn:de:0030-drops-192203}, doi = {10.4230/LIPIcs.AFT.2023.31}, annote = {Keywords: Total-Order Broadcast, Atomic Broadcast, Proof of Stake, Random Beacon} }
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