US Patent 11388591 Perimeter offline secure exchange of access control token

A method, access control system, and readers for use in an access control system are described. One example of the disclosed method providers the ability to securely augment an existing physical access control system that relies on access control tokens (e.g., credentials) with a secure mobile-based solution allowing the secure local offline exchange of a new access control token for another that can be used with the existing installed access control system.