A Comment on the 'Basic Security Theorem' of Bell and LaPadula

Many claim that the security model developed by Bell and LaPadula and used as a basis for numerous prototype military computer systems is superior to others partly because its authors prove a "Basic Security Theorem" that applies to it. This paper shows that the theorem does not support such claims since it can be proven for security models that are obviously not secure. Further, the theorem provides little help to those who design and implement secure systems.