Ask HN: User Verification for Government Employees

Hi HN community, I'm building a web app where govt workers and citizens can interact with one another. If a citizen lives in a zipcode that the govt worker serves, they can interact.

It is important that neither group be impersonated. - How can I verify the identity of both groups? - How can I verify that the citizen lives in the zipcode they provided?

Any tools, libraries, methods, services are welcome!

Thank you in advance.