Paper 2016/997

More Efficient Commitments from Structured Lattice Assumptions

Carsten Baum and Ivan Damgård and Vadim Lyubashevsky and Sabine Oechsner and Chris Peikert

Abstract

We present a practical construction of an additively homomorphic commitment scheme based on structured lattice assumptions, together with a zero-knowledge proof of opening knowledge. Our scheme is a design improvement over the previous work of Benhamouda et al. in that it is not restricted to being statistically binding. While it is still possible to instantiate our scheme to be either statistically binding or statistically hiding, it is most efficient when both hiding and binding properties are only computational. This results in approximately a factor of 4 reduction in the size of the proof and a factor of 6 reduction in the size of the commitment over the aforementioned scheme.

Note: Improved version with configurable binding and hiding, better comparison with previous work.