A Logarithmic-Size Certificateless Traceable Ring Signature Based on SM2-DualRing and its Application in Data Sharing

As a special ring signature, a traceable ring signature (TRS) provides limited anonymity and traceability, and has been shown useful in many practical applications such as anonymous voting. On the other hand, DualRing, a novel generic construction of ring signature introduced in CRYPTO 2021, can reduce computation and communication costs. Recently, building upon DualRing, Ye et al. proposed a lattice-based TRS that introduced TripleRing construction to ensure traceability. However, the proposed TRS encounters issues with certificate management and linear signature size. To address these concerns, we introduce a certificateless TRS with logarithmic size based on SM2-DualRing (SDR-CTRS) in the discrete logarithm setting. The SDR-CTRS leverages the TripleRing construction and non-interactive sum argument. Security analysis indicates that our SDR-CTRS satisfies tag-linkability, anonymity, and exculpability under the discrete logarithm hypothesis. Theoretical analysis shows that the SDR-CTRS features logarithmic communication cost and acceptable computation cost. Additionally, the SDR-CTRS does not require a fully trusted party during the tracking phase. Finally, to illustrate the practicality of the ring signature, we present a blockchain-based data sharing system with conditional privacy protection based on it.