arXiv subjects

Jelizaveta Vakarjuk

Publications and source records attributed to Jelizaveta Vakarjuk.

3 recordsLinked to original sources

arXiv2026

PRETTINESS -- Privacy pResErving aTTrIbute maNagEment SyStem

European Digital Identity (EUDI) Wallet aims to provide end users with a way to get attested credentials from issuers, and present them to different relying parties. An important property mentioned in the regulatory frameworks is the possibility to revoke a previously issued credential. While it is possible to issue a short-lived credential, in some cases it may be inconvenient, and a separate revocation service which allows to revoke a credential at any time may be necessary. In this work, we propose a full end-to-end description of a generic credential revocation system, which technically relies on a single server and secure transmission channels between parties. We prove security of the proposed revocation functionality in the universal composability model, and estimate its efficiency based on a proof-of-concept implementation.

cs.CR↗

arXiv2024

Privacy-preserving server-supported decryption

In this paper, we consider encryption systems with two-out-of-two threshold decryption, where one of the parties (the client) initiates the decryption and the other one (the server) assists. Existing threshold decryption schemes disclose to the server the ciphertext that is being decrypted. We give a construction, where the identity of the ciphertext is not leaked to the server, and the client's privacy is thus preserved. While showing the security of this construction, we run into the issue of defining the security of a scheme with blindly assisted decryption. We discuss previously proposed security definitions for similar cryptographic functionalities and argue why they do not capture the expected meaning of security. We propose an ideal functionality for the encryption with server-supported blind threshold decryption in the universal composability model, carefully balancing between the meaning of privacy, and the ability to implement it. We construct a protocol and show that it is a secure implementation of the proposed functionality in the random oracle model.

cs.CR↗

arXiv2023

Trust assumptions in voting systems

Assessing and comparing the security level of different voting systems is non-trivial as the technical means provided for and societal assumptions made about various systems differ significantly. However, trust assumptions concerning the involved parties are present for all voting systems and can be used as a basis for comparison. This paper discusses eight concrete voting systems with different properties, 12 types of parties involved, and seven general security goals set for voting. The emerging trust relations are assessed for their criticality, and the result is used for comparison of the considered systems.

cs.CR↗