> Church and Turing already proved there are no general solutions to the Entscheidungsproblem. I'm skeptical that that is as strongly connected as you seem be

> Church and Turing already proved there are no general solutions to the Entscheidungsproblem. I'm skeptical that that is as strongly connected as you seem be implying. The inability to give a general method to determine whether a program halts / whether the output of a program has some property, does not seem to me to say all that much about the ability to verify images or other sources of information. You would not say that, because of the lack of general solutions to the Entscheidungsproblem, that you can't verify that some message was signed with the private key corresponding to a particular public key, would you? If not, then what is it about verifying that a photograph isn't doctored that the Entscheidungsproblem implies a problem for, but which it doesn't imply a problem for checking a cryptographic signature?