Zero-knowledge for homomorphic key-value commitments with applications to privacy-preserving ledgers

Matteo Campanelli, Felix Theodor Engelmann, Claudio Orlandi

Research output: Conference Article in Proceeding or Book/Report chapterArticle in proceedingsResearchpeer-review

Abstract

Commitments to key-value maps (or, authenticated dictionaries) are an important building block
in cryptographic applications, including cryptocurrencies and distributed file systems.
In this work we study short commitments to key-value maps with two additional properties: double-hiding
(both keys and values should be hidden) and homomorphism (we should be able to combine two commitments
to obtain one that is the “sum” of their key-value openings). Furthermore, we require these commitments to
be short and to support efficient transparent zero-knowledge arguments (i.e., without a trusted setup).
As our main contribution, we show how to construct commitments with the properties above as well as
efficient zero-knowledge arguments over them. We additionally discuss a range of practical optimizations
that can be carried out depending on the application domain.
Finally, we formally describe a specific application of commitments to key-value maps to scalable anonymous
ledgers. We show how to extend QuisQuis (Fauzi et al. ASIACRYPT 2019). This results in an efficient,
confidential multi-type system with a state whose size is independent of the number of transactions.
Original languageEnglish
Title of host publicationInternational Conference on Security and Cryptography for Networks
Volume2022
Publication date15 Sept 2022
Pages761–784
ISBN (Print)978-3-031-14790-6
ISBN (Electronic)978-3-031-14791-3
DOIs
Publication statusPublished - 15 Sept 2022

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