Cryptology ePrint Archive: Report 2021/1303

Black-Box Accumulation Based on Lattices

Sebastian H. Faller and Pascal Baumer and Michael Klooß and Alexander Koch and Astrid Ottenhues and Markus Raiber

Abstract: Black-box accumulation (BBA) is a cryptographic protocol that allows users to accumulate and redeem points, e.g. in payment systems, and offers provable security and privacy guarantees. Loosely speaking, the transactions of users remain unlinkable, while adversaries cannot claim a false amount of points or use points from other users. Attempts to spend the same points multiple times (double spending) reveal the identity of the misbehaving user and an undeniable proof of guilt. Known instantiations of BBA rely on classical number-theoretic assumptions, which are not post-quantum secure. In this work, we propose the first lattice-based instantiation of BBA, which is plausibly post- quantum secure. It relies on the hardness of the Learning with Errors (LWE) and Short Integer Solution (SIS) assumptions and is secure in the Random Oracle Model (ROM). Our work shows that a lattice-based instantiation of BBA can be realized with a communication cost per transaction of about 199 MB if built on the zero-knowledge protocol by Yang et al. (CRYPTO 2019) and the CL-type signature of Libert et al. (ASIACRYPT 2017). Without any zero-knowledge overhead, our protocol requires 1.8 MB communication.

Category / Keywords: cryptographic protocols / Lattice-based Cryptography, Black-box Accumulation (BBA), Electronic Funds Transfer, Security and Privacy, Learning with Errors (LWE), Short Integer Solution (SIS)

Original Publication (with minor differences): 18th IMA International Conference on Cryptography and Coding

Date: received 27 Sep 2021

Contact author: sebastian faller at mailbox org, astrid ottenhues at kit edu, michael klooss at kit edu, markus raiber at kit edu, alexander koch at kit edu, ueeap at student kit edu

Available format(s): PDF | BibTeX Citation

Note: This is the full version of a paper accepted at the 18th IMA International Conference on Cryptography and Coding. It will be updated to include a link to the published version, when available.

Version: 20210928:182815 (All versions of this report)

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