VRaaS: Verifiable Randomness as a Service on Blockchains

Jacob Gorman; Lucjan Hanzlik; Aniket Kate; Easwar Vivek Mangipudi; Pratyay Mukherjee; Pratik Sarkar; Sri AravindaKrishnan Thyagarajan

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 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 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. Moreover, we investigate the minimalism of the framework. Towards that, first we show that, the two transactions in-built in our framework are actually for any randomness service to support the essential qualities. We also discover in other designs such as Algorand beacon, Pyth VRF and Band VRF, captured within our framework.

Note: This is the full version containing the detailed security proofs.

Metadata

Available format(s): PDF
Category: Foundations
Publication info: Published elsewhere. Minor revision. 38th IEEE Computer Security Foundations Symposium
Keywords: Randomness Service Blockchain Verifiable Random Function Smart Contract Universal 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: 2025-04-16: last of 3 revisions; 2024-06-14: received; See all versions
Short URL: https://ia.cr/2024/957
License: 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}
}