From multilevel security to multiple independent levels of security/safety: the evolution illustrated through a novel cross-domain architecture

Since years organisations classify information according to security schemes and various criteria. The requirement to protect information characterised by a hierarchy of sensitivity levels led to the definition of multilevel security. Multilevel security represents one of the toughest problems that security engineers are still facing, due to the fact that it is difficult to manage securely information at different classification levels on the same electronic device or network. It concerns wired and wireless communications, from personal area and wireless sensor networks to wide area and satellite networks. The problem becomes even more critical when users with various clearances, privileges, and roles need to operate simultaneously on these security-motley data. Recently, a new approach gathered the endorsement of industry and academia, the so-called multiple independent levels of security/safety. In this article, we show the evolution that drove the multilevel security into this new paradigm, highlighting the benefits and the drawbacks of the former together with the improvement of the latter and its open issues. A novel cross-domain solution is presented as the thread in-between the two approaches.