Let's say we have Bob, Alice and third party.
Bob make message signature hash and upload to third party, then encrypt message with Alice pub key and send it to Alice
Alice receive message and decrypt it. She also ask third party for message hash and verify message.
However. What if Bob upload random signature hash to third party. And when Alice try to verify message, she will not be able to verify it.
Question is: How Alice can verifiable prove, that message not corresponding to signature hash, without revealing message?
- Also third party shouldn't know original message content from Bob. Third party only storing signature hashes.