An Isogeny-Based Adaptor Signature Using SQISign

Abstract

Transactions on blockchains can prove very costly, so as a solution to avoid these large costs, schemes involving payment channel networks have been developed. One approach to implementing these off-chain forms of payment securely involves adaptor signatures.

Previous work has established a generic construction of adaptor signatures using signature schemes that satisfy a couple of key properties. Unfortunately, most post-quantum signature schemes do not satisfy these properties, meaning more work needs to be done to develop quantum-safe solutions. We introduce a new post-quantum adaptor signature that uses SQISign as its underlying signature. SQISign has been shown to be significantly faster and to require less storage than any other isogeny-based signature, giving our construction potential for significant improvements in the way of efficiency. We give the details of the new scheme, provide proofs of its security, and estimate memory costs.