A device may include an authentication server and a server. The authentication server may receive a first form of a password from a client in accordance with an authentication protocol, and authenticate the client based on a comparison of the first form to a value derived from a second form of the password stored in a password database. The comparison fails when the first form is not comparable to a value derived from the second form. The server may establish a secure connection to the client, receive a plain-text password from the client over the secure connection, authenticate the client by comparing a value derived from the plain-text password with a value derived from the second form, and update the password database with a third form of the password that permits the authentication server to successfully authenticate the client when the authentication server receives the first form.