About getting in
Six claims about addresses. Every one of them fails, which is worth noting on its own, because this is the part of the subject where confident wrong answers are most common and most expensive.
Why they all fail the same way
Each claim below is a different way of saying that something other than a signature can establish an address. Ranking can. A directory can. The address loading can. Somebody you trust can. None of them can, because establishing that a party holds a key requires that party to demonstrate it, and no channel carries that.
The useful consequence is that you do not need six separate judgements. One check, run on arrival, works identically regardless of how you got there.