Lattice-based linkable linearly homomorphic ring signature scheme

Under the paradigm of cloud computing and big data, lattice-based linearly homomorphic ring signature schemes aim to simultaneously satisfy the requirements of verifiable data outsourcing computation and identity anonymity while resisting quantum computing threats. However, existing schemes suffer from two major limitations: the sizes of ring public keys and signatures grow linearly with the number of ring members, leading to efficiency bottlenecks in large-scale settings; and the absence of effective traceability mechanisms for signer behavior creates regulatory blind spots. To address these challenges, this paper constructs a lattice-based linkable linearly homomorphic ring signature scheme. First, by designing a novel ring public key construction that aggregates individual keys into a unified structure, the ring public key size is compressed to a constant level independent of the ring size, significantly improving storage efficiency. Second, a privacy-preserving link tag mechanism is introduced, enabling verifiers to determine whether two signatures originate from the same signer without revealing the signer’s identity. Under the random oracle model, we formally prove that the scheme satisfies anonymity under full key exposure, unforgeability under internal corruption, linkability, and weak context hiding privacy, based on the hardness of standard lattice problems. Theoretical analysis and experimental results demonstrate that the proposed scheme achieves storage advantages over existing schemes, along with verification efficiency.