Chaya Ganesh, Aarhus University. “Efficient Zero-Knowledge Proof Systems for Composite Statements”

Position:  Postdoctoral Researcher

Current Institution:  Aarhus University

Abstract:  Efficient Zero-Knowledge Proof Systems for Composite Statements

Zero-knowledge proofs provide a powerful tool which allows a prover to convince a verifier that a statement is true without revealing any further information.  It is known that every language in NP has a zero knowledge proof system thus opening up several cryptographic applications.  While true in theory, designing proof systems that are efficient enough to be used in practice remains challenging.  Known approaches in prior work are each suited for certain representations of statements.  But statements that arise in practice are composite statements that have components represented in different ways:  Boolean/arithmetic circuit algebraic representation.  For instance, verifying an RSA signature involves checking a hash function H (represented as a boolean circuit) and computing exponentiations (algebraic group operations).  Given a message m and a purported signature s verification involves checking if s^e mod N=H(m) for the RSA public key (e N).  The state of the art fails to take advantage of the best of all worlds and has to forgo the efficiency of one approach to obtain the other’s.  My research focuses on new zero-knowledge proofs techniques that are suitable for proving such composite statements.   In particular, my work is in designing efficient protocols for proving a wide class of statements motivated by applications in different settings:  protocols that use symmetric-key operations (and very few public key operations) that are suited where interaction is acceptable; non-interactive proofs that allow efficient verification for applications on the blockchain where the proof needs to be short and posted on the chain; protocols that achieve the strong notion of adaptive composable zero-knowledge that is necessary for applications in secure multi-party computation.

Chaya Ganesh is a postdoctoral researcher in the Cryptography group at Aarhus University.  She received her PhD from New York University under the supervision of Prof. Yevgeniy Dodis in September 2017.  She has completed internships at Microsoft Research Bell Labs and Visa Research.  Her research is on secure computation protocols and zero-knowledge proofs.  She maintains research interest in theoretical and applied Cryptography. She was awarded the Henry MacCracken fellowship by NYU during her doctoral studies.  She has served on the program committees of CANS 2018 and SEC 2018.