# Proving anonymous credential presentation

In a CL-based or CKS-based anonymous credential system, how can a verifier $$V$$ prove that a credential holder $$H$$ has presented it a credential that has been issued by an issuer $$I$$ without identifying $$H$$? I could not come up with a simple solution using the anonymous credential.

I think that an additional mechanism different from anonymous credentials is necessary in order to make the verifier able to prove that some holder made it a proof presentation. Since the holders proof presentation must be "unrepeatable" by verifier, the holder must provide some additional data (data is just a very basic definition) to verifier so that verifier must be able to prove that this presentation happened to someone else with that data somehow. And in a multi-use credential system (such as CL-based or CKS-based) we can not apply this situation with the facilities of anonymous credentials as far as I know. I dont have a problem with applying this scenario by using additional mechanisms/cryptographic primitives. But I am wondering if it is possible to implement using the facilities of aforementioned anonymous credential systems.

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• Look, digital signatures are a useful tool in authentications systems; in fact, it is an important building block. When you restrict: "without ... encrypted values"... What do you mean specifically? – McFly Mar 25 at 15:47
• Thanks for your answer. I tried to edit and detail my question. – kentakenta Mar 26 at 3:19