Multilevel security: reprise

Multilevel security is the prevention of unauthorized disclosure among multiple information classes. The threat source for the disclosures includes unauthorized users and subverted software operating on behalf of authorized users. The terminology might be more explicit if we could call this concept multidomain confidentiality, but it is worth resisting multiplying terminology. Nonetheless, we should understand that multilevel security means multidomain confidentiality. The author asks if there is less need for multilevel security today, and if there is still a need, how we might address it.