Paper 2023/103

Fair Delivery of Decentralised Randomness Beacon

Runchao Han, Monash University, Data61
Jiangshan Yu, Monash University

Thesecurityofmanyprotocolssuchasvotingandblockchains relies on a secure source of randomness. Decentralised Randomness Beacon (DRB) has been considered as a promising approach, where a set of participants jointly generates a sequence of random outputs. While the DRBs have been extensively studied, they failed to capture the advantage that some participants learn random outputs earlier than other participants. In time-sensitive protocols whose execution depends on the randomness from a DRB, such an advantage allows the adversary to behave adaptively according to random outputs, compromising the fairness and/or security in these protocols. In this paper, we formalise a new property, delivery-fairness, to quantify the advantage. In particular, we distinguish two aspects of delivery-fairness, namely length-advantage, i.e., how many random outputs an adversary can learn earlier than correct participants, and time-advantage, i.e., how much time an adversary can learn a given random output earlier than correct participants. In addition, we prove the lower bound of delivery-fairness showing optimal guarantee. We further analyse the delivery-fairness guarantee of state-of-the-art DRBs and discuss insights, which, we show through case studies, could help improve delivery-fairness of existing systems to its optimal.

Available format(s)
Cryptographic protocols
Publication info
Published elsewhere. The 27th International Conference on Financial Cryptography and Data Security (FC’23)
Decentralised randomness beaconblockchain
Contact author(s)
me @ runchao rocks
jiangshan yu @ monash edu
2023-01-27: approved
2023-01-27: received
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Short URL
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      author = {Runchao Han and Jiangshan Yu},
      title = {Fair Delivery of Decentralised Randomness Beacon},
      howpublished = {Cryptology ePrint Archive, Paper 2023/103},
      year = {2023},
      note = {\url{}},
      url = {}
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