Who developed one of the first mathematical models of a multilevel security computer system?

A. Diffie and Hellman

B. Clark and Wilson

C. Bell and LaPadula

D. Gasser and Lipner

C. Bell and LaPadula

Explanation:

The first mathematical models of multilevel security computer system was developed by Bell and Lapadula. Their full names are David Elliot Bell and Leonard J. Lapadula. Their model used to define the concept of modes of access, secure state machine and outlined the rules of access.