Outline for May 16, 1997
- Greetings and Felicitations
- Theme: military model does not provide enough controls for commercial fraud,
etc. because it does not cover the right aspects of integrity
- Data items: "Condtrained Data Items" (CDI) to which the model applies,
"Unconstrained Data Items (UDIs) to which no integrity checks are applied,
"Integrity Verification Procedures" (IVP) that verify conformance to the
integrity spec when IVP is run, "Transaction Procedures" (TP) takes system from
one well-formed state to another
- Certification and enforcement rules:
C1. All IVPs must ensure that all
CDIs are in a valid state when the IVP is run.
- C2. All TPs must be certified to be valid,
and each TP is assocated with a set of CDIs it is authorized to manipulate.
- E1. The system must maintain these lists and must ensure only those TPs
mannipulate those CDIs;
- E2: The system must maintain a list of User IDs, TP, and CDIs that
that TP can manipulate on behalf of that user,
and must ensure only those executions are performed.
- C3. The list of relations in E2 must be certified to meet the
separation of duty requirement.
- E3. The sysem must authenticate the identity of each user
attempting to execute a TP.
- C4. All TPs must be certified to write to an append-only CDI (the log)
all information necessary to resonstruct the operation.
- C5. Any TP taking a UDI as an input must be certified to perform only
valid transformations, else no transformations, for any possible value of
the UDI. The
transformation should take the input from a UDI to a CDI, or the UDI is
rejected (typically, for edits as the keyboard is a UDI).
- E4. Only the agent permitted to certify entities may change the list
of such entities associated with a TP. An agent that can certify an entity
may not have any execute rights with respect to that entity
- Discuss logging with log file as a CDI
- Different orientation than BLP; goal is to support well-formed transactions,
not classification levels
- Chinese Wall Policy
- Arises as legal defense to insider trading on London stock exchange
- Low-level entities are objects; all objects concerning the same corporation
form a CD (company dataset); CDs whose corporations are in competition are
grouped into COIs (Conflict of Interest classes)
- Intuitive goal: keep one subject from reading different CDs in the same COI,
or reading one CD and writing to another in same COI
- Simple Security Property: Read access granted if the object (a) is in the
same CD as an object already accessed by the subject, or (b) is in a CD in an
entirely different COI. Assumes correct initialization
- Theorems: (1) Once a subject has accessed an object, only other objects in
that CD are available within that COI; (2) subject has access to at most 1
dataset in each COI class
- Exceptions: sanitized information
- *-Property: Write access is permitted only if (a) read access is permitted
by the simple security property; and (b) no object in a different CD in that
COI can be read, unless it contains sanitized information
- Comparison to BLP: (1) ability to track history; (2) in CW, subjects choose
which objects they can access but not in BLP; (3) CW requires both mandatory
and discretionary parts, BLP is mandatory only.
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Department of Computer Science
University of California at Davis
Davis, CA 95616-8562
Page last modified on 6/4/97