A system includes a database and a processor. The database stores a key indicating that a user previously accessed a first subsystem. An authentication string stores a first part of the key and a first authentication server stores a second part. The processor receives a request from the user seeking access to a second subsystem. The processor launches a first virtual host to receive the authentication string and send it to the first authentication server, to extract the first part of the key, assemble a test key including the first and second parts of the key, and determine that the test key matches the key stored in the database. The first virtual host then launches a second virtual host to receive login credentials and send them to a second authentication server to authenticate the user. In response, the second virtual host provides the user with access to the second subsystem.