Faster threshold-SM2 with identifiable abort and non-interactive online signing

Abstract Threshold signatures are essential for fault-tolerant applications among groups of users, such as in blockchain transactions. SM2 is a digital signature standard in China and ISO, yet its threshold variant is less developed compared to international alternatives such as ECDSA. Specifically, modern threshold signatures offer identifiable abort (ID-abort) and non-interactive online signing, but these features make threshold-SM2 costly, limiting its real-world application. In this paper, we introduce a fast threshold-SM2 with ID-abort and non-interactive online signing. We design a technology for ID-abort by checking hard-to-verify pseudononces based on their mappings in a group. By putting the message-independent computations to a presigning phase, we achieve a non-interactive online signing. We prove that our threshold-SM2 is secure in the dishonest majority model and implement it using Golang. Theoretical analysis and experimental results demonstrate that our threshold-SM2 provides rich functionalities with good performance, significantly reducing computational and communication costs compared to the state-of-the-art threshold-SM2 by Liang and Chen (FCS’ 24).