Homomorphic Proofs and Applications

This paper introduces and formalizes homomorphic proofs,which allow ’adding’ proofs and ’adding’ their statementsto get a new proof of the ’sum’ statement. We proposea construction of homomorphic proofs and show one of itsapplications which is a new accumulator scheme with del-egatable non-membership (NM) proofs. We use this accu-mulator in extending the BCCKLS scheme [3] to achievea delegatable anonymous credential with revocation system.Informally, the accumulator’s delegatable NM proofs enableuser A, without revealing her identity, to delegate to userB the ability to prove that A’s identity is not included in ablacklist which could even be updated afterward. Moreover,the delegation should be redelegatable, unlinkable and ver-ifiable. Security of the proposed schemes is provable. Weimplement a system for Revocation of Anonymous Creden-tials (RAC ) that bases on the proposed accumulator. RACcould provide revocation for several anonymous credentialsystems.