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From: Arant, Michael (email@example.com)
Date: Thu Oct 25 2001 - 07:23:17 CDT
Steve Wang said...
>I am reading the "The CISSP Prep Guide" and have the following question
about the Biba integrity model (page 205): in the book, the simple integrity
axiom is interpreted as "no read down". why no read down for integrity?
Will read down hurt integrity?
I had the same befuddlement at first. Try to see it this way. "Reading up"
in the context of integrity classification can do nothing but improve the
quality of your knowledge. Seen in reverse, "reading down" in the context
of integrity classification will contaminate your knowledge. By not
"writing up", you can't contaminate the knowledge of those with higher
clearances. Simplistic perhaps, but it works for me.
** VA: Security by Design **
Michael S. Arant, CISSP
Cyber Security Office (045C)
Department of Veterans Affairs, Room 352A
810 VT Ave., NW.
Washington, DC 20420
From: Steve Wang [mailto:firstname.lastname@example.org]
Sent: Monday, October 22, 2001 12:34 PM
Subject: The Biba integrity model
I am reading the "The CISSP Prep Guide" and have the following question
about the Biba integrity model (page 205):
in the book, the simple integrity axiom is interpreted as "no read down".
why no read down for integrity? Will read down hurt integrity?
I also saw another description of the Biba integrity model (from another
lecture) as follows
a.. Simple Integrity Property: A subject s may modify an object o only
if the clearance of the subject dominates the classification of the
object (this rule, no write up, is called * integrity axiom in the book)
b.. Integrity *-Property A subject s with read access to an object o can
modify an object p only if the classification of o dominates the
classification of p
Obviously the above statement is NOT the same (indeed it is much
different) as what is said in the book. It sounds to me that
the above one in the lecture is more reasonable.
Could somebody help me?.