Randomness is an important resource in computing. In the blockchain/web3 space, many decentralized finance (DeFi) and particularly gaming applications, such as Lottery, Poker etc. crucially require a good source of randomness.  In this setting generating good randomness is particularly non-trivial — this is because the typical source of randomness relies on (computation on) private source, and it is notoriously hard to support private computation on blockchain. Therefore, off-chain private sources are used. However, one needs to ensure that the off-chain randomness sources perform the task correctly in order to ensure crucial properties, such as unpredictability, unbiasbaility etc. This leads to a new requirement, namely public verifiability, which guarantees that each randomness can be verified publicly. Typically, this is ensured by deploying a cryptographic object, known as verifiable random functions (VRF). While many existing on-chain VRF services satisfy the crucial requirements mentioned above, they often become too expensive to use. In this talk, I am going to mainly speak about new designs for providing on-chain randomness service, where randomness can be delivered at much cheaper price while preserving the crucial functionalities.

His talk is based on the ACM CCS 2023 paper and other on-going works, jointly done with Aniket Kate (Purdue/Supra), Jacob Gorman (Supra), Lucjan Hanzlik (CISPA), Easwar Mangipudi (Supra), Siva Maradana (ISI Kolkata), Pratik Sarkar (Supra) and Aravind Thyagarajan (NTT, USA).