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Lecture 14 - b Temporal separation – separation by...

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Class Notes: October 28, 2008 Covert channels Storage channels Timing channels Identifying potential covert channels Very difficult a. Shared resource matrix a. Designed to tell you all possible routes for information to flow throughout your system. b. Develop a matrix of resources (in rows) and processes (in columns) b. Information Method a. Is really just a flow analysis from a program syntax (can be automated within a compiler) A:=B B A C:=A A C, - B->C F(x), x f Steganography: hide information within a picture Read Chapter 3.5 Operating System Security
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Protection in a general purpose operating system What can operating systems protect, and what methods are available for this protection? What do we need to protect? 1. User programs (from each other) 2. Objects a. Memory b. Shareable I/O Devices c. Shareable programs and sub-procedures d. Networks e. Shareable data Security Methods of an Operating System 1. Separation a. Physical separation – separation by physical location
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Unformatted text preview: b. Temporal separation – separation by time (things run at different times) c. Logical separation – No logical connection between the two d. Cryptographic separation (the complexity of a-d increases with the letters descending, also the security decreases as from a-b and b-c) But we also need sharing , otherwise what is the point of having an operating system. Options: 1. Do nothing 2. Isolate processes that are unaware of each other 3. Share all 4. Share nothing 5. Share via access limitations (checks allowability of each access based on each object) 6. Share by capabilities (allows dynamic creation of access rights) 7. Limit the use of an object (monitors the usage after access is given to make sure that you aren’t doing anything bad). The difficulty to implement increases from 1-7, the fineness of the protection also increases from 1-7....
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Lecture 14 - b Temporal separation – separation by...

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