Cryptology ePrint Archive: Report 2020/845

Post-Quantum Adaptor Signatures and Payment Channel Networks

Muhammed F. Esgin and Oguzhan Ersoy and Zekeriya Erkin

Abstract: Adaptor signatures, also known as scriptless scripts, have recently become an important tool in addressing the scalability and interoperability issues of blockchain applications such as cryptocurrencies. An adaptor signature extends a digital signature in a way that a complete signature reveals a secret based on a cryptographic condition. It brings about various advantages such as (i) low on-chain cost, (ii) improved fungibility of transactions, and (iii) advanced functionality beyond the limitation of the blockchain's scripting language.

In this work, we introduce the first post-quantum adaptor signature, named LAS. Our construction relies on the standard lattice assumptions, namely Module-SIS and Module-LWE. There are certain challenges specific to the lattice setting, arising mainly from the so-called knowledge gap in lattice-based proof systems, that makes the realization of an adaptor signature and its applications difficult. We show how to overcome these technical difficulties without introducing additional on-chain costs.

Our evaluation demonstrates that LAS is essentially as efficient as an ordinary lattice-based signature in terms of both communication and computation. We further show how to achieve post-quantum atomic swaps and payment channel networks using LAS.

Category / Keywords: public-key cryptography / Post-Quantum, Blockchain, Lattice, Adaptor Signature, Scriptless Script, Payment Channel Network

Original Publication (in the same form): ESORICS 2020

Date: received 7 Jul 2020, last revised 11 Jul 2020

Contact author: muhammed esgin at monash edu,o ersoy@tudelft nl,z erkin@tudelft nl

Available format(s): PDF | BibTeX Citation

Version: 20200712:123609 (All versions of this report)

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