Efficient verifiably encrypted ECDSA schemes from Castagnos-Laguillaumie and Joye-Libert encryptions

Publication Type

Journal Article

Publication Date

3-2024

Abstract

A Verifiably Encrypted Signature (VES) scheme encrypts a digital signature in a way that allows the public to verify the validity of the encrypted signature. Recently, several practical VES schemes for ECDSA have been proposed to enable escrowed transactions with cryptocurrencies. However, these schemes are inefficient in terms of both communication and computation, or require a large lookup table. In this paper, we present two efficient VES schemes for ECDSA that improve upon previous work. The first scheme is based on Castagnos-Laguillaumie (CL) encryption, while the second is based on modified Joye-Libert (JL) encryption. Our benchmark shows that our schemes outperform existing constructions by a factor of at least 2 in both computation and communication. Additionally, our solution does not rely on any lookup table. We demonstrate that these schemes can also be generalized to design VES for Schnorr signature scheme and EdDSA. The main technical contribution of this paper, which is of independent interest, is a zero-knowledge proof for the equality of the discrete log of an elliptic-curve point and that of a JL ciphertext. Importantly, the security of our proof does not rely on any non-standard assumptions.

Keywords

Cryptography, Standards, Protocols, Bandwidth, Symbols, Public key, Contracts

Discipline

Information Security

Research Areas

Cybersecurity

Areas of Excellence

Digital transformation

Publication

IEEE Transactions on Information Forensics and Security

Volume

19

First Page

4161

Last Page

4173

ISSN

1556-6013

Identifier

10.1109/tifs.2024.3375622

Publisher

Institute of Electrical and Electronics Engineers

Copyright Owner and License

Authors

Additional URL

https://doi.org/10.1109/tifs.2024.3375622

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