### (Public) Verifiability For Composable Protocols Without Adaptivity Or Zero-Knowledge

Carsten Baum, Bernardo David, and Rafael Dowsley

##### Abstract

The Universal Composability (UC) framework (FOCS '01) is the current standard for proving security of cryptographic protocols under composition. It allows to reason about complex protocol structures in a bottom-up fashion: any building block that is UC-secure can be composed arbitrarily with any other UC-secure construction while retaining their security guarantees. Unfortunately, some protocol properties such as the verifiability of outputs require excessively strong tools to achieve in UC. In particular, obviously secure'' constructions cannot directly be shown to be UC-secure, and verifiability of building blocks does not easily carry over to verifiability of the composed construction. In this work, we study Non-Interactive (Public) Verifiability of UC protocols, i.e. under which conditions a verifier can ascertain that a party obtained a specific output from the protocol. The verifier may have been part of the protocol execution or not, as in the case of public verifiability. We consider a setting used in a number of applications where it is ok to reveal the input of the party whose output gets verified and analyze under which conditions such verifiability can generically be achieved using cheap'' cryptographic primitives. That is, we avoid having to rely on adaptively secure primitives or heavy computational tools such as NIZKs. As Non-Interactive Public Verifiability is crucial when composing protocols with a public ledger, our approach can be beneficial when designing these with provably composable security and efficiency in mind.

Note: Added examples of using the public verifiability compiler.

Available format(s)
Category
Cryptographic protocols
Publication info
Preprint. MINOR revision.
Keywords
Public VerifiabilityUniversal ComposabilityCompiler
Contact author(s)
cbaum @ cs au dk
bernardo @ bmdavid com
rafael @ dowsley net
History
2021-06-14: last of 6 revisions
See all versions
Short URL
https://ia.cr/2020/207

CC BY

BibTeX

@misc{cryptoeprint:2020/207,
author = {Carsten Baum and Bernardo David and Rafael Dowsley},
title = {(Public) Verifiability For Composable Protocols Without Adaptivity Or Zero-Knowledge},
howpublished = {Cryptology ePrint Archive, Paper 2020/207},
year = {2020},
note = {\url{https://eprint.iacr.org/2020/207}},
url = {https://eprint.iacr.org/2020/207}
}

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