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Verify encrypted signature using encrypted version of publickey without decrypt them

cn flag

I try to explain the problem (maybe it's trivial): is there a way to do the following: sign a message with private key, send encrypted version of signature and an encrypted version of publickey to verifier in a manner that the verifier can verify the signature without decrypt publickey and signature? Thanx in advance for the answer.

István András Seres avatar
cf flag
Sure! It can be surely done. You can solve your problem with zero-knowledge proofs. However, the concrete efficiency of your proofs (prover and verifier efficiency and proof size) will depend a lot on the applied signature and encryption scheme. Can you specify which encryption and signature scheme do you need to use?
An Ca avatar
cn flag
Thx Istvan for the quick reply, I don't have any particular constraint on the choice, maybe AES and ECC will do the job
István András Seres avatar
cf flag
AES is not so ZKP-friendly. There are a lot of AND gates if you think of the AES function as an arithmetic circuit. You should use a signature and an encryption scheme that is more ZKP friendly. My suggestion would be to use a pairing friendly curve and then e.g., Boneh-Boyen signature scheme with ElGamal-encryption. These two fit well in a Groth-Sahai proof. The knowledge of a Boneh-Boyen signature is quite easy to prove with Groth-Sahai proofs. But, I'm sure there are many other signature and encryption schemes that can be efficiently be proved with an appropriately chosen ZK proof system.
An Ca avatar
cn flag
Many thx for the suggestion Istvan, I'll take a look to the literature. In the meanwhile, I was thinking about homomorphic encryption in a whitebox context
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