A Central Key Authority (CKA) database includes PuK-linked account information of users, wherein the PuK-linked account information maintained in the database for each user includes, (a) a public key of a user device that generates digital signatures, (b) information securely linked with the public key of the device within a secure environment of the manufacture of the device, and (c) third-party account identifiers each of which identifies to a third-party an account of the user that is maintained with the third-party and that has been associated with the user's public key by the third-party.