A military style security system’s objective is to lock all information within the system. In this system, confidentiality is the most important aspect. Integrity and availability is not the priority. It is naturally a MAC policy where users are not trusted for their discretion. System pre-assigns users with their rights over classified files. In this model, we assume that the users cannot memorize crucial information and disclose it to an outsider, such actions would lead to severe penalties.
Bell-LaPadula Policy:
Bell-LaPadula policy, named after its creators, is a confidentiality policy. It’s security levels are Top Secret, Secret, Classified, and Unclassified. The policy only considers clearance and classification. In this model, information can not flow downwards or else it will result into a leakage. The dominancy flows downwards meaning that the most powerful subject is placed at the top.
In this model, you can either read or write. It has two parts: read (simple security condition) and write (* property). Subject s can read an object o if and only if when level of security of s is higher than or equal to level of security of o. Subject s can write to object of if and only if when the level of security of o is higher or equal to level of security of s.
Subject s can read object o, iff L(s) ≥L(o)
Subject scan write object o, iff L(o) ≥L(s)
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