An apparatus may include a processor that may be caused to receive an authentication request to authenticate a user. The authentication request may include a one-time username associated with an identity of the user and a secret credential of the user. The processor may further identify, in a user registry, a unique user identifier based on the one-time username, and authenticate the user based on the unique user identifier and the secret credential. The apparatus may update the user registry to prevent the one-time username from being used again to identify the user for authentication.