Efficient Unique Ring Signatures from Lattices

Unique ring signatures (URS) were introduced by Franklin and Zhang (FC 2012) as a unification of linkable and traceable ring signatures. In URS, each member within a ring can only produce, on behalf of the ring, at most one signature for a message. Applications of URS potentially are e–voting systems and e–token systems. In blockchain technology, URS have been implemented for mixing contract. However, existing URS schemes are based on the Discrete Logarithm Problem, which is insecure in the post-quantum setting. In this paper, we design a new lattice-based URS scheme where the signature size is logarithmic in number of ring members. The proposed URS exploits a Merkle tree-based accumulator as building block in the lattice setting. Our scheme is secure under the Short Integer Solution and Learning With Rounding assumptions in the random oracle model.