Stony Brook University Computer Science

CS Ph.D. student Bong Gon Kim will be giving a talk on the following topics: 

1) Defining VRFs and how they are used in Alogrand blockchains
2) Elliptic Curve-based VRF construction and its security reduction proofs to q-Diffie Hellman Inversion (q-DHI) and q-Decisional Bilinear Diffie Hellman Inversion (q-DBDHI) assumptions. 
3) Introduction of smart contract-based VRF in Blockchain.

Date & Time: Friday, October 25, 2 PM

Venue: B204

Abstract

Verifiable Random Functions (VRFs) are essentially digital signature schemes for Pseudo Random Functions (PRFs), providing the correctness of PRF output normally in Non-Interactive Zero-Knowledge (NIZK) way. Many existing number-theoretic VRFs are either RSA-based or Elliptic Curve(EC)-based constructions using bilinear pairing cryptography. Hence, they are normally heavy in computations (even not safe under quantum-capable adversaries due to Shor's algorithm) and thus supported off-chain when used in the Blockchain context to avoid high gas costs. Also, the VRFs' secret keys need to be accessed securely, and the randomness should comply with the deterministic Blockchain consensus nature while the smart contract is decentralized under the existence of untrusted nodes. Besides, surprisingly, the requirement of VRFs' statistical randomness performance has not been captured in many existing works, to the best of our knowledge. This seminar will introduce what a VRF is and explore how Algorand's VRF(RFC9381) is used in the Blockchain and how an EC-based VRF is constructed via bilinear pairing with the security reduction to q-Diffie Hellman Inversion (q-DHI) and q-Decisional Bilinear Diffie Hellman Inversion (q-DBDHI) assumptions. Also, a brief introduction of how a smart contract-based Verifiable Random Function can be constructed in a Blockchain context.

Bio

Bong Gon Kim (Graduate Student Member, IEEE) received the B.S. degree in electrical and electronics and the M.S. degree in computer science from Yonsei University, Seoul, South Korea. He is currently pursuing the Ph.D. degree with the Department of Computer Science, University of Stony Brook. From 2003 to 2018, he worked as a Senior Engineer with the SW platform Lab, Samsung Electronics, South Korea. He has been involved in numerous projects of mobile communication, Android applications, and Linux systems during the time in Samsung. He is also interested in the redactable blockchain system using chameleon hashes. His current research interests include mainly the security and privacy management in blockchain systems.