Pre-Conference Talk by WANG Jiaheng | LAS+: Lattice-based Adaptor Signature with Stronger Security

Adaptor signatures (AS) enable conditional signing and atomic release of secrets, supporting applications such as payment channels and blockchain atomic swaps. While LAS, proposed by Esgin et al. at ESORICS 2020, was the first post-quantum lattice-based adaptor signature scheme, we identify gaps in its unlinkability and pre-verification soundness.

This work introduces LAS+, a lattice-based adaptor signature scheme with stronger security guarantees. We demonstrate that the original LAS scheme fails to achieve these two properties and present a polynomial-time distinguisher based on boundary-density statistics to expose its unlinkability weakness. To address these issues, LAS+ incorporates tuned rejection sampling to achieve weak unlinkability and a non-interactive zero-knowledge (NIZK) proof to ensure pre-verification soundness. We prove that LAS+ satisfies extractability, unique extractability, weak unlinkability, and pre-verification soundness under the Module Short Integer Solution (M-SIS) and Module Learning With Errors (M-LWE) assumptions. Applied to UTXO-based atomic swaps, LAS+ provides stronger on-chain privacy than the original scheme. 

This is a Pre-Conference talk for 29th Information Security Conference (ISC 2026).
 

Jiaheng WANG is a third-year Ph.D. candidate in Computer Science at Singapore Management University (SMU), Singapore, supervised by Prof. Guomin Yang and Prof. Haiyang Xue. His research interests include post-quantum cryptography, particularly lattice-based signatures and zero-knowledge proofs. His current work focuses on designing secure and efficient lattice-based cryptographic schemes and rigorously analyzing their security. The research he will be presenting in this talk is based on his paper recently accepted by the 2026 Information Security Conference (ISC 2026).