# Is there a zero knowledge proof of knowledge of a Waters sigature?

I am looking for a ZK PoK of a digital signature. I have seen constructions that work for ElGamal signatures (see this older paper), but need to work with Waters signatures, as described here.

Has anyone seen a construction that could work in this case?

• Yes, of course, you can build a ZK proof/argument of knowledge of the Waters signature by Fiat-Shamir heuristic or Groth-Sahai 07 proof method. The statement of this ZK proof/argument is "the ciphertext $c$ contains a Water signature $\sigma$ on $m$.". And the related witnesses are the signature $\sigma$ and your secret key $\alpha$. Aug 30 at 4:12
• Many thanks @mingalex - I am finally learning the proper appreciation for Groth-Sahai. Do you happen to be aware of any software libraries that support the construction of proofs in their framework? Sep 3 at 3:37
• There was an implementation of the Groth-Sahai NIZK. You can launch it directly without installing PBC lib, if you do not want to use the type D&G pairing. Sep 6 at 1:35