🚀 go-pugleaf

Bishop is correct. Look at the definition of ITP and the axioms for the
Ring Policy.

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Bill Arbaugh					www.cs.umd.edu/~waa
University of Maryland				     waa@cs.umd.edu
College Park					       301.405.2774
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On Thu, 9 Nov 2000, Arunesh Mishra wrote:

> Hi All,
> 
> Bishop mentions that the information path theorem holds
> for the Ring Policy. I think it cannot hold because a 
> subject can read from an object of much lower integrity
> (say 1) and write to a less lower integrity level (say 2 )
> thus violating the theorem !
>  Was this a typo or what I have written does not make
> sense ?
> 
> Arunesh.
> 
> 
> 
> 
> ------------------------------------------------------------------
> Arunesh Mishra                              First Year PhD Student
> Room 4140, A.V. Williams,                       arunesh@cs.umd.edu
> College Park, Md 20742.                    www.cs.umd.edu/~arunesh 
> University of Maryland                   Dept. of Computer Science
> ------------------------------------------------------------------
> 
> Be what you want to be !
> 
> 

Bill
I am wondering if arunesh is correct.The ring policy staates that a  
subject can read any object irrespecive of its integrity level-this allows
us to read an object from an integrity level lower than the subject's.

I guess some numbers will make thinsg simpler.

assume 
I(s)=5
I(o1)=3
now s can read o1.
Assume I(o2)=4
therefore s can write to o2.
Because s reads 01 and modifies 02 an ITP exists.
But now I(02) <= I(01) does not hold and hence Theorem 6.2 doesnt hold.

Are we making any wrong assumptions here??Are we making the right
interpretation??Please let us know
sincerely
naren



Narendar Shankar M
Graduate Fellow
Computer Science Dept.
4157-A.V.Williams Building,
University Of Maryland ,College Park
MD-20742

WEBMAIL- narendar_m_s@yahoo.co.uk
HOMEPAGE- www.narendarms.com

You're reading too much into the problem.  What does the definition of an
Information transfer path say?  It (ITP) is only concerned with the flow
of information in one direction, i.e. with respect to ITP read-down is
permitted.

-------------------------------------------------------------------
Bill Arbaugh					www.cs.umd.edu/~waa
University of Maryland				     waa@cs.umd.edu
College Park					       301.405.2774
-------------------------------------------------------------------
On Thu, 9 Nov 2000, Narendar Shankar wrote:

> Bill
> I am wondering if arunesh is correct.The ring policy staates that a  
> subject can read any object irrespecive of its integrity level-this allows
> us to read an object from an integrity level lower than the subject's.
> 
> I guess some numbers will make thinsg simpler.
> 
> assume 
> I(s)=5
> I(o1)=3
> now s can read o1.
> Assume I(o2)=4
> therefore s can write to o2.
> Because s reads 01 and modifies 02 an ITP exists.
> But now I(02) <= I(01) does not hold and hence Theorem 6.2 doesnt hold.
> 
> Are we making any wrong assumptions here??Are we making the right
> interpretation??Please let us know
> sincerely
> naren
> 
> 
> 
> Narendar Shankar M
> Graduate Fellow
> Computer Science Dept.
> 4157-A.V.Williams Building,
> University Of Maryland ,College Park
> MD-20742
> 
> WEBMAIL- narendar_m_s@yahoo.co.uk
> HOMEPAGE- www.narendarms.com
> 
> 
> 
> 

Hi everybody,
  I am trying to access the Bishops chapters that are put up on the
web. However the web site has not been responding for the last couple of
days and as a result I cannot read that material for the exam. I was
wondering if anyone has a copy of the Bishops chapters can you pl email
them to me.
Thank you
kulki

There is some confusion on this problem which I am speaking with
Matt.  The ring policy (looking solely at the axioms) does not satisfy thm
6.2.  However, the ring policy prohibits indirect modifications.  With
this constraint, it does satisfy Thm 6.2.  But, an ITP (in my opinion) is
a form of an indirect modification.

I'll try and provide more feedback when I get it.

Bill

-------------------------------------------------------------------
Bill Arbaugh					www.cs.umd.edu/~waa
University of Maryland				     waa@cs.umd.edu
College Park					       301.405.2774
-------------------------------------------------------------------
On Fri, 10 Nov 2000, Bill Arbaugh wrote:

> 
You're reading too much into the problem.  What does the definition of an
> Information transfer path say?  It (ITP) is only concerned with the flow
> of information in one direction, i.e. with respect to ITP read-down is
> permitted.
> 
> -------------------------------------------------------------------
> Bill Arbaugh					www.cs.umd.edu/~waa
> University of Maryland				     waa@cs.umd.edu
> College Park					       301.405.2774
> -------------------------------------------------------------------
> On Thu, 9 Nov 2000, Narendar Shankar wrote:
> 
> > Bill
> > I am wondering if arunesh is correct.The ring policy staates that a  
> > subject can read any object irrespecive of its integrity level-this allows
> > us to read an object from an integrity level lower than the subject's.
> > 
> > I guess some numbers will make thinsg simpler.
> > 
> > assume 
> > I(s)=5
> > I(o1)=3
> > now s can read o1.
> > Assume I(o2)=4
> > therefore s can write to o2.
> > Because s reads 01 and modifies 02 an ITP exists.
> > But now I(02) <= I(01) does not hold and hence Theorem 6.2 doesnt hold.
> > 
> > Are we making any wrong assumptions here??Are we making the right
> > interpretation??Please let us know
> > sincerely
> > naren
> > 
> > 
> > 
> > Narendar Shankar M
> > Graduate Fellow
> > Computer Science Dept.
> > 4157-A.V.Williams Building,
> > University Of Maryland ,College Park
> > MD-20742
> > 
> > WEBMAIL- narendar_m_s@yahoo.co.uk
> > HOMEPAGE- www.narendarms.com
> > 
> > 
> > 
> > 
> 
>