U4. Chinese Wall

U4. Chinese Wall

1. Aimed at a 'real' problem of preventing conflicts of interest

   • Golden Rule = There must be no flow of information that causes a conflict of interest.

2. Simple security (ss) property:

   • A subject may only be granted access to an object if:
     • the object is in the same company dataset as an object already accessed by the subject
     • the object does not belong to any of the conflict of interest classes of objects already accessed by the subject
   • deals with direct information flow

3. Star property

   • deals with indirect flow
   • A subject s is permitted write access to an object only if s has no read access to any object o', which is in a different company dataset and is unsanitised
   • One of the implications of the *-property is that access rights of subjects change dynamically with every access operation.

4. You need to understand and appreciate how a different type of security policy can be described in terms of a security model.