Consider a multi-level security system given below. The four security levels are arranged with the most sensitive at the top and less sensitive at the bottom. At the right is a set of documents grouped by their security levels. In the middle, individuals are grouped by their security clearance. If 'no read up' and 'no write down' properties for confidentiality are satisfied, can Thomas update the Electronic Mail Files'? Why or why not? Explain briefly.
TOP SECRET (TS)
Tamara, Thomas
Personnel Files
SECRET (S)
Sally, Samuel, Claire, Clarence
Electronic Mail Files - Activity Log Files
CONFIDENTIAL (C), UNCLASSIFIED (UC)
Ulaley, Ursula
Telephone List Files