Paper 2023/221

Bicorn: An optimistically efficient distributed randomness beacon

Kevin Choi, New York University
Arasu Arun, New York University
Nirvan Tyagi, Cornell University
Joseph Bonneau, New York University, a16z Crypto Research

We introduce Bicorn, an optimistically efficient distributed randomness protocol with strong robustness under a dishonest majority. Bicorn is a "commit-reveal-recover" protocol. Each participant commits to a random value, which are combined to produce a random output. If any participants fail to open their commitment, recovery is possible via a single time-lock puzzle which can be solved by any party. In the optimistic case, Bicorn is a simple and efficient two-round protocol with no time-lock puzzle. In either case, Bicorn supports open, flexible participation, requires only a public bulletin board and no group-specific setup or PKI, and is guaranteed to produce random output assuming any single participant is honest. All communication and computation costs are (at most) linear in the number of participants with low concrete overhead.

Available format(s)
Cryptographic protocols
Publication info
Published elsewhere. Financial Cryptography and Data Security 2023
randomness beacondistributed randomnessblockchaintimed commitmentverifiable delay function
Contact author(s)
kc2296 @ nyu edu
2023-02-20: approved
2023-02-17: received
See all versions
Short URL
Creative Commons Attribution


      author = {Kevin Choi and Arasu Arun and Nirvan Tyagi and Joseph Bonneau},
      title = {Bicorn: An optimistically efficient distributed randomness beacon},
      howpublished = {Cryptology ePrint Archive, Paper 2023/221},
      year = {2023},
      note = {\url{}},
      url = {}
Note: In order to protect the privacy of readers, does not use cookies or embedded third party content.