Apparatus for protecting the confidentiality of a user's password during a remote login authentication exchange between a user node and a directory service node of a distributed, public key cryptography system includes a specialized server application functioning as an intermediary agent for the login procedure. The login agent has responsibility for approving the user's login attempt and distributing a private key to the user. However, the login agent is not trusted with the user's password and is therefore a "semi-trusted" node. In another aspect of the invention, a login protocol enables remote authentication of the user password without transmitting the password over the network.