Managing a database of a central key authority for a plurality of account holders, each account holder having at least one account associated with a public key of a public-private key pair of that account holder, includes maintaining for each account holder a record of information pertaining to the accounts of that account holder associated with the public keys of the account holder. The information pertaining to the accounts of an account holder includes (a) a public key of a user device that generates digital signatures, and (b) 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.