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


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
Publication date15 Sept 2022
ISBN (Print)978-3-031-14790-6
ISBN (Electronic)978-3-031-14791-3
Publication statusPublished - 15 Sept 2022


  • short commitments
  • double-hiding
  • homomorphic commitments
  • zero-knowledge arguments
  • scalable anonymous ledgers


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