TY - GEN
T1 - Not a COINcidence
T2 - 34th International Symposium on Distributed Computing, DISC 2020
AU - Cohen, Shir
AU - Keidar, Idit
AU - Spiegelman, Alexander
N1 - Publisher Copyright: © Shir Cohen, Idit Keidar, and Alexander Spiegelman; licensed under Creative Commons License CC-BY 34th International Symposium on Distributed Computing (DISC 2020).
PY - 2020/10/1
Y1 - 2020/10/1
N2 - King and Saia were the first to break the quadratic word complexity bound for Byzantine Agreement in synchronous systems against an adaptive adversary, and Algorand broke this bound with near-optimal resilience (first in the synchronous model and then with eventual-synchrony). Yet the question of asynchronous sub-quadratic Byzantine Agreement remained open. To the best of our knowledge, we are the first to answer this question in the affirmative. A key component of our solution is a shared coin algorithm based on a VRF. A second essential ingredient is VRF-based committee sampling, which we formalize and utilize in the asynchronous model for the first time. Our algorithms work against a delayed-adaptive adversary, which cannot perform after-the-fact removals but has full control of Byzantine processes and full information about communication in earlier rounds. Using committee sampling and our shared coin, we solve Byzantine Agreement with high probability, with a word complexity of Oe(n) and O(1) expected time, breaking the O(n2) bit barrier for asynchronous Byzantine Agreement.
AB - King and Saia were the first to break the quadratic word complexity bound for Byzantine Agreement in synchronous systems against an adaptive adversary, and Algorand broke this bound with near-optimal resilience (first in the synchronous model and then with eventual-synchrony). Yet the question of asynchronous sub-quadratic Byzantine Agreement remained open. To the best of our knowledge, we are the first to answer this question in the affirmative. A key component of our solution is a shared coin algorithm based on a VRF. A second essential ingredient is VRF-based committee sampling, which we formalize and utilize in the asynchronous model for the first time. Our algorithms work against a delayed-adaptive adversary, which cannot perform after-the-fact removals but has full control of Byzantine processes and full information about communication in earlier rounds. Using committee sampling and our shared coin, we solve Byzantine Agreement with high probability, with a word complexity of Oe(n) and O(1) expected time, breaking the O(n2) bit barrier for asynchronous Byzantine Agreement.
KW - Byzantine agreement
KW - Shared coin
KW - Sub-quadratic consensus protocol
KW - VRF
UR - http://www.scopus.com/inward/record.url?scp=85109584024&partnerID=8YFLogxK
U2 - 10.4230/LIPIcs.DISC.2020.25
DO - 10.4230/LIPIcs.DISC.2020.25
M3 - منشور من مؤتمر
T3 - Leibniz International Proceedings in Informatics, LIPIcs
BT - 34th International Symposium on Distributed Computing, DISC 2020
A2 - Attiya, Hagit
Y2 - 12 October 2020 through 16 October 2020
ER -