You may be taking a narrow view of "the problem". Stella Rimington,
head of British (internal) intelligence (MI5) courageously spoke some
clear truth a couple of decades ago. She said there isn't and cannot
be a reliable connection between information and an active body in the
world with agency. In other words, she thought "identity" is a weak
idea and forcefully opposed the idea of "ID cards".
Individuals may occasionally be of interest in intelligence, but less
than you think. Identity really comes from banking, law and medicine
so that we don't give the wrong person money, drugs or put the wrong
person in jail. It's low-level, procedural, civic stuff.
Beyond that there's a lot more dark, unwanted applications of identity
and we forget how much it is a cultural artefact of the
individualistic society we presently inhabit.
We do have plenty of nearly-good ways of _re_cognising_ a living
person, if we have previously "cognised" them. Images, voices, faces,
and various biological scans are all limited and likely to be defeated
with coming technology.
So separating "trust" (as expected behaviour) from identity is a major
challenge, and a most fascinating one. They are not the same thing.