## Cryptology ePrint Archive: Report 2019/1452

Leakage-Resilient Lattice-Based Partially Blind Signatures

D. Papachristoudis and D. Hristu-Varsakelis and F. Baldimtsi and G. Stephanides

Abstract: Blind signature schemes (BSS) play a pivotal role in privacy-oriented cryptography. However, with blind signature schemes, the signed message remains unintelligible to the signer, giving them no guarantee that the blinded message he signed actually contained valid information. Partially-blind signature schemes (PBSS) were introduced to address precisely this problem. In this paper we present the first leakage-resilient, lattice-based partially-blind signature scheme in the literature. Our construction is provably secure in the random oracle model (ROM) and offers quasilinear complexity w.r.t. key/signature sizes and signing speed. In addition, it offers statistical partial blindness and its unforgeability is based on the computational hardness of worst-case ideal lattice problems for approximation factors in $˜ O(n^4)$ in dimension $n$. Our scheme benefits from the subexponential hardness of ideal lattice problems and remains secure even if a (1-o(1)) fraction of the signer’s secret key leaks to an adversary via arbitrary side-channels. Several extensions of the security model, such as honest-user unforgeability and selective failure blindness, are also considered and concrete parameters for instantiation are proposed.

Category / Keywords: cryptographic protocols / Post-Quantum Cryptography, Lattices, Partially-blind signatures, Privacy-preserving applications, Anonymity

Original Publication (with minor differences): IET Information Security
DOI:
10.1049/iet-ifs.2019.0156

Date: received 15 Dec 2019, last revised 15 Dec 2019

Contact author: dpapachristoudis at uom edu gr

Available format(s): PDF | BibTeX Citation

Short URL: ia.cr/2019/1452

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