Imagine a scenario, where you have a person p online which has a very good profile. For example, you want to hire them. This person is identified by a public key and has some information I about him signed with this public key. However, there is no way of contacting this person.
Now somebody p' shows up and wants to prove that he is p. He does not have his computer with him, so he can't sign anything with his private key.
What would "I" have to be so that it is possible to identify him an make sure the person who is in front of you is not a swindler?
I thought maybe biometric photos could be something? I guess a human would easily see when you would try to wear a mask to pretend you are p? I think I've seen that one can put something on the finger to get another fingerprint, so I guess finger prints are not a good identifier? Are there other identifiers of a person which are hard / impossible to forge, without having to create a shared secret? (Note that in this scenario, the biometric data is public)
One identifier which cannot be forged is DNA. But getting the DNA data is also quite expensive / time consuming, I guess?