Paper 2018/857

Raptor: A Practical Lattice-Based (Linkable) Ring Signature

Xingye Lu and Man Ho Au and Zhenfei Zhang

Abstract

We present (linkable) Raptor, the first lattice-based (linkable) ring signature that is practical. Our scheme is as fast as classical solutions; while the size of the signature is roughly 1.3 KB per user. Our designs are based on a completely new generic construction that is provable secure in random oracle model. Prior to our work, all existing lattice-based solutions are analogues of their discrete-log or pairing-based counterparts. We give instantiations to both standard lattice setting, as a proof of concept, and NTRU lattice, as an efficient instantiation. Our main building block is a so called Chameleon Hash Plus (CH+) function, which may be of independent research interest.