Implementation and Performance Analysis of Homomorphic Signature Schemes

Homomorphic signatures allow to validate computation on signed data. Alice, holding a dataset {m1,& mldr;,mt} uses her secret key sk to sign these data and stores the authenticated dataset on a remote server. The server can later (publicly) compute m=f(m1,...,mt) together with a signature sigma certifying that m is indeed the correct output of the computation f. Over the last fifteen years, the problem of realizing homomorphic signatures has been the focus of numerous research works, with constructions now ranging from very efficient ones supporting linear functions to very expressive ones supporting (up to) arbitrary circuits. In this work we tackle the question of assessing the practicality of schemes belonging to this latter class. Specifically, we implement the GVW lattice based scheme for circuits from STOC 2015 (both the standard and the ring variant) and two, recently proposed, pairings based constructions building from functional commitments. Our experiments show that (both) pairings based schemes outperform GVW on all fronts.