## CryptoDB

### Paper: A New Approach to Efficient Non-Malleable Zero-Knowledge

Authors: Allen Kim , Stony Brook University Xiao Liang , Stony Brook University Omkant Pandey , Stony Brook University Search ePrint Search Google Slides CRYPTO 2022 Non-malleable zero-knowledge, originally introduced in the context of man-in-the-middle attacks, serves as an important building block to protect against concurrent attacks where different protocols may coexist and interleave. While this primitive admits almost optimal constructions in the plain model, they are several orders of magnitude slower in practice than standalone zero-knowledge. This is in sharp contrast to non-malleable commitments where practical constructions (under the DDH assumption) have been known for a while. We present a new approach for constructing efficient non-malleable zero-knowledge for all languages in NP, based on a new primitive called instance-based non-malleable commitment (IBNMC). We show how to construct practical IBNMC by leveraging the fact that simulators of sub-linear zero-knowledge protocols can be much faster than the honest prover algorithm. With an efficient implementation of IBNMC, our approach yields the first general-purpose non-malleable zero-knowledge protocol that achieves practical efficiency in the plain model. All of our protocols can be instantiated from symmetric primitives such as block-ciphers and hash functions, have reasonable efficiency in practice, and are general-purpose. Our techniques also yield the first efficient non-malleable commitment scheme without public-key assumptions.
##### BibTeX
@inproceedings{crypto-2022-32111,
title={A New Approach to Efficient Non-Malleable Zero-Knowledge},
publisher={Springer-Verlag},
author={Allen Kim and Xiao Liang and Omkant Pandey},
year=2022
}