Paper 2024/957

VRaaS: Verifiable Randomness as a Service on Blockchains

Jacob Gorman, Supra Research
Lucjan Hanzlik, CISPA Helmholtz Center for Information Security
Aniket Kate, Supra Research, Purdue University West Lafayette
Easwar Vivek Mangipudi, Supra Research
Pratyay Mukherjee, Supra Research
Pratik Sarkar, Supra Research
Sri AravindaKrishnan Thyagarajan, University of Sydney
Abstract

Web3 applications, such as on-chain games, NFT minting, and leader elections necessitate access to unbiased, unpredictable, and publicly verifiable randomness. Despite its broad use cases and huge demand, there is a notable absence of comprehensive treatments of on-chain verifiable randomness services. To bridge this, we offer an extensive formal analysis of on-chain verifiable randomness services. We present the $first$ formalization of on-chain verifiable randomness in the blockchain setting by introducing the notion of Verifiable Randomness as a Service (VRaaS). We formally define VRaaS using an ideal functionality $\mathcal{F}_{\sf VRaaS}$ in the Universal Composability model. Our definition not only captures the core features of randomness services, such as unbiasability, unpredictability, and public verifiability, but also accounts for many other crucial nuances pertaining to different entities involved, such as smart contracts. Within our framework we study a generic design of Verifiable Random Function~(VRF)-based randomness service -- where the randomness requester provides an input on which the randomness is evaluated as VRF output. We show that it does satisfy our formal VRaaS definition. Furthermore, we show that the generic protocol captures many real-world randomness services like Chainlink VRF and Supra dVRF. We investigate whether our definition is minimalistic in terms of the desired security properties - towards that, we show that a couple of insecure constructions fall short of realizing our definition. Using our definition we also discover practical vulnerabilities in other designs such as Algorand beacon, Pyth VRF and Band VRF that offer on-chain verifiable randomness.

Note: Improved the author fields

Metadata
Available format(s)
PDF
Category
Foundations
Publication info
Preprint.
Keywords
Randomness ServiceBlockchainVerifiable Random FunctionSmart ContractUniversal Composability
Contact author(s)
jacobgorman613 @ gmail com
hanzlik @ cispa de
aniket @ purdue edu
e mangipudi @ supraoracles com
pratyay85 @ gmail com
iampratiksarkar @ gmail com
t srikrishnan @ gmail com
History
2024-06-18: revised
2024-06-14: received
See all versions
Short URL
https://ia.cr/2024/957
License
Creative Commons Attribution
CC BY

BibTeX

@misc{cryptoeprint:2024/957,
      author = {Jacob Gorman and Lucjan Hanzlik and Aniket Kate and Easwar Vivek Mangipudi and Pratyay Mukherjee and Pratik Sarkar and Sri AravindaKrishnan Thyagarajan},
      title = {{VRaaS}: Verifiable Randomness as a Service on Blockchains},
      howpublished = {Cryptology {ePrint} Archive, Paper 2024/957},
      year = {2024},
      url = {https://eprint.iacr.org/2024/957}
}
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