Distributed randomness using weighted VRFs
Incorporating shared randomness into blockchains enhances their versatility and security. Benny Pinkas (Bar-Ilan University and Aptos Labs) focuses on how blockchains can autonomously generate fresh randomness for each new block, particularly in proof-of-stake systems where validators have different stakes. This introduces a weighted threshold setting where authorization relies on the cumulative weight of a subset of the participants, rather than on the subset size.
He introduces three cryptographic protocols to enable generating shared randomness in a weighted setting: A publicly verifiable secret sharing scheme (PVSS), which is weighted and aggregatable; a weighted distributed key generation protocol (DKG); and a weighted verifiable unpredictable function (VUF). Importantly, in the VUF protocol, which is the protocol that is run most frequently, the computation and communication costs of participants are independent of their weight. This feature is crucial for scalability. The resulting system was implemented and deployed on the Aptos blockchain.
About the presenter
Benny is a researcher at Aptos Labs and a professor of computer science at Bar-Ilan University, where he was formerly the director of the Center for Research in Applied Cryptography and Cyber Security. He received his PhD from the Weizmann Institute in 2000 and is a Fellow of the International Association for Cryptologic Research (IACR). He has worked as a researcher at Intertrust Technologies, Hewlett-Packard, Google, and VMware. His main research areas are cryptography, computer security and privacy, with a focus on secure multi-party computation.
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