Edit WYSIWYGattachfile Attach PDF Raw View►More Actions▼More Actions

Restore topic to revision: You will be able to review the topic before saving it to a new revision

Copy text and form data to a new topic (no attachments will be copied though).
Name of copy:
You will be able to review the copied topic before saving

Rename/move topic... scans links in all public webs (recommended)
Rename/move topic... scans links in CBI_ComputerSecurity web only
Delete topic... scans links in all public webs (recommended)
Delete topic... scans links in CBI_ComputerSecurity web only

Revision Date Username Comment
809 Sep 2015 - 10:13ThomasMisa 
709 Sep 2015 - 10:12ThomasMisa 
612 Nov 2014 - 21:21ThomasMisa 
512 Nov 2014 - 21:13ThomasMisa 
403 Oct 2013 - 16:03norqu036? 
325 Jun 2013 - 14:36NicLewis 
225 Jun 2013 - 14:00NicLewis 
125 Jun 2013 - 12:36NicLewis 

Render style:     Context:

 History: r8 < r7 < r6 < r5 < r4
[X] Hide this message.
Notice: On June 30, 2016, UMWiki service will be decommissioned. If you have information in UMWIki that needs to be preserved, you should make plans to move it before that date. Google Sites is anticipated to be the most popular and appropriate alternative for users because it offers a more modern and user-friendly interface and unlimited capacity. To learn more about the features of Google Sites and other alternatives, and to identify which one best fits your needs, see the University’s Website Solution Selection Guide. If you have concerns or would like help regarding this change and your options, please contact Technology Help at help@umn.edu
You are here: UMWiki>CBI_ComputerSecurity Web>Systems>SystemsPSOS (09 Sep 2015, ThomasMisa)

Current Activitieslock Who is Who?lock People Programs Publications CSHW_2014 Systems Events Mechanisms

Provably Secure Operating System (PSOS)


The Provably Secure Operating System (PSOS) began in 1973 as an SRI International project to develop a secure general-purpose operating system. Unlike the KSOS project, PSOS was a full operating system, rather than a security kernel. SRI pursued the PSOS operating system project in addition to KSOS because the SRI team determined that a full operating system offered greater flexibility than a security kernel, which was tailored to a single security model.

Beginning with a general system design, the SRI team developed a complete system specification comprised of multiple software modules. The goal was to produce an operating system that adhered to both the Bell-LaPadula model of data confidentiality, and a second model that provided for data integrity. Although the project began in 1973, the project report in 1980 revealed the continuing difficulties the SRI team experienced in verifying the operating system as provably secure. Groups outside SRI -- including a smaller security kernel project at the University of California at Los Angeles, the Autodin (Automatic Digital Network) II secure packet-switching project for ARPAnet, and Honeywell's computer security efforts(1) -- experienced similar frustrations with verification. These difficulties reflected the undeveloped state of formal verification procedures, the lack of verification tools, and the realization that much of the Bell-LaPadula model was too simple for the complex needs of a computer operating system.(2)(3)(4)


1 : See project interviews with Earl Boebert and Richard Kain.

2 : lock Richard J. Feiertag and Peter G. Neumann, "The Foundations of a Provably Secure Operating System (PSOS)," 329-334, in Proceedings of the National Computer Conference 1979, New York: AFIPS Press, 1979, 329-334. (Login required)

3 : lock P. G. Neumann, et al., A Provably Secure Operating System, Menlo Park, CA: Stanford Research Institute 1975, 0-1 - 0-5. (Login required)

4 : Donald MacKenzie, Mechanizing Proof: Computing, Risk, and Trust, Cambridge, MA: MIT Press, 2001, 168-170.

Topic revision: r8 - 09 Sep 2015 - 10:13:31 - ThomasMisa
Signed in as lewi0740 (NicLewis) | Sign out
UMWiki UMWiki
This site is powered by FoswikiCopyright © by the contributing authors. All material on this collaboration platform is the property of the contributing authors.
Ideas, requests, problems regarding UMWiki? Send feedback