Paper 2025/443

Homomorphic Signature-based Witness Encryption and Applications

Alireza Kavousi, University College London
István András Seres, Eötvös Loránd University
Abstract

Practical signature-based witness encryption (SWE) schemes recently emerged as a viable alternative to instantiate timed-release cryptography in the honest majority setting. In particular, assuming threshold trust in a set of parties that release signatures at a specified time, one can ``encrypt to the future'' using an SWE scheme. Applications of SWE schemes include voting, auctions, distributed randomness beacons, and more. However, the lack of homomorphism in existing SWE schemes reduces efficiency and hinders deployment. In this work, we introduce the notion of homomorphic SWE (HSWE) to improve the practicality of timed-release encryption schemes. We show one can build HSWE using a pair of encryption and signature schemes where the uniqueness of the signature is required when the encryption scheme relies on injective one-way functions. We then build three HSWE schemes in various settings using BLS, RSA, and Rabin signatures and show how to achieve a privacy-preserving variant that only allows extracting the homomorphically aggregated result while keeping the individual plaintexts confidential

Metadata
Available format(s)
PDF
Category
Cryptographic protocols
Publication info
Preprint.
Keywords
homomorphic encryptionsignature-based witness encryptiontimed cryptographyidentity-based encryption
Contact author(s)
a kavousi @ cs ucl ac uk
seresistvanandras @ gmail com
History
2025-03-10: approved
2025-03-07: received
See all versions
Short URL
https://ia.cr/2025/443
License
Creative Commons Attribution
CC BY

BibTeX

@misc{cryptoeprint:2025/443,
      author = {Alireza Kavousi and István András Seres},
      title = {Homomorphic Signature-based Witness Encryption and Applications},
      howpublished = {Cryptology {ePrint} Archive, Paper 2025/443},
      year = {2025},
      url = {https://eprint.iacr.org/2025/443}
}
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