One of the First Mathematical Models of a Multilevel-Security Computer System

C.

In 1973 Bell and LaPadula created the first mathematical model of a multi-level security system.

The following answers are incorrect: Diffie and Hellman.

This is incorrect because Diffie and Hellman was involved with cryptography.

Clark and Wilson.

This is incorrect because Bell and LaPadula was the first model.

The Clark-Wilson model came later, 1987

Gasser and Lipner.

This is incorrect, it is a distractor.

Bell and LaPadula was the first model.

The correct answer is C. Bell and LaPadula.

Bell and LaPadula developed one of the first mathematical models of a multilevel-security computer system in 1973. Their model, known as the Bell-LaPadula model, is designed to enforce confidentiality policies in computer systems by preventing unauthorized disclosure of information from higher-level security domains to lower-level ones.

The Bell-LaPadula model is based on two main concepts: the "no read up" rule and the "no write down" rule. The "no read up" rule states that a subject at a lower level of security clearance should not be able to read information from a higher level of clearance. The "no write down" rule states that a subject at a higher level of security clearance should not be able to write information to a lower level of clearance.

The Bell-LaPadula model also introduces the concepts of "subjects" (users, processes, or devices that can access the system) and "objects" (resources such as files or data that are protected by the system). Access to objects is controlled by a security policy that determines whether a subject is allowed to read, write, or execute the object.

The model has been widely used in the development of secure operating systems, network security protocols, and access control mechanisms. It has also been extended and refined over the years to address new security threats and challenges.