Database Protection |access control mechachanism | mandatory access control mechanism

MANDATORY ACCESS CONTROL MECHANISM

INTRODUCTION-

• In many applications an additional security policy is needed that classifies data and users based on security classes.This approach is known as mandatory access control.
• The need for multilevel security exists in government military and intelligence applications as well as many industrial and corporate applications.

TYPICAL SECURITY CLASSES

• TS(Top Secret)
• Secret(S)
• Confidential(C)
• Unclassified(U)  

      TS>=S>=C>=U

• TS is the highest level
• U is the lowest level

The commonly used model for multilevel security known as BELL - LAPADULA MODEL

BELL - LAPADULA MODEL

• Classifies each subject(user,account,program) and object (relation,tuple,column,view,operation) into one of the security classifications TS,S,U or C.
• We will refer to the clearance of a subject S as class(S) and to the classification of an object O as class(O).

Two restrictions are enforced on data access based on the subject/ object classifications.

1. A subject S is not allowed read access to an object O unless class(S) >= class(O). This is known as simple security property and intuitive .
2. A subject S is not allowed to write an object O unless class(S) <= class(O).This is known as star property and is less intuitive.

A multilevel relation scheme R with n attributes would be represented as-

R ( A1,C1,A2,C2-------------------An ,Cn,TC)