Abstract: A secure network comprises a plurality of terminals connected to a common file server. Each terminal holds in its memory an encrypted unique variable and unique first and second conjugates for each user authorized to use that terminal. The unique variable is generated, at the time of registration of a user, from master keys stored on a separate disc or other memory medium, the identity number of the terminal, and the identity number of the user to be registered. A password is randomly generated and used to encrypt the unique variable. The first conjugate is a randomly generated message, which is encrypted using the password to generate the second conjugate. In order to log on at a given terminal, the user must enter his password, and the terminal then uses this password as the key to encrypt the first conjugate, and compares it with the stored second conjugate. If the first and second conjugate agree, the terminal is enabled for the person to use. A high level of security is therefore attained.