This paper examines some questions concerning commercial computer security integrity policies. We give an example of a dynamic separation of duty policy which cannot be implemented by TCSEC based mechanisms alone, yet occurs in the real commercial world, and can be implemented efficiently in practice. We examine and describe a commercial computer security product in wide use for ensuring the integrity of financial transactions, show that it implements a well defined and sensible integrity policy that includes separation of duty, yet fails to meet either the TCSEC criteria or the Clark and Wilson rules.
M. J. Nash, K. R. Poland