feb09 - CS 426 class Feb 09, 2012

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CS 426 class Feb 09, 2012 www.cs.purdue.edu/homes/ssw/cs426/{index.html,syll.pdf,outline} Trusted Operating System security - Read Chapter 5 When we discussed ordinary OS, our point of view was the user and security services: protect memory, files, and other objects and perform user authentication. An OS is *trusted* if we are confident that it provides these 4 services consistently and effectively. Now we discuss trusted OS from the point of view of the designer The four major underpinnings of a trusted OS are: 1. Policy - a set of well-defined, consistent, clear, implementable rules for security Examples: military, Clark-Wilson, Chinese wall 2. Model of the environment to be secured and a way to do it. The model represents the policy. Examples: lattices, Bell-La Padua, Biba, Graham-Denning, HRU, TG 3. Design - a means to implement the policy - topics like object reuse, audit, logs, intrusion detection Examples: least privilege, open design, access control, 4. Trust - why should users trust the OS? Examples: examine policy, model, design; penetration testing; formal verification and validation; evaluation We call it a "trusted OS" rather than a "secure OS" because security is either/or = yes/no; trust is graded security is a property of the presenter; trust of the receiver security is asserted; trust is judged security is a goal for a system; trust is a characteristic of a system A user judges how much to trust an OS based on: 1. Functional correctness - Does the OS work correctly? 2. Integrity enforcement - Does the OS maintain correct data
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This note was uploaded on 02/23/2012 for the course CS 426 taught by Professor Staff during the Spring '08 term at Purdue.

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feb09 - CS 426 class Feb 09, 2012

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