cse443-lecture-14-accesscontrol

cse443-lecture-14-accesscontrol - Access Control CMPSC 443...

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CMPSC 443 Introduction to Computer and Network Security - Spring 2012 - Professor Jaeger Access Control CMPSC 443 - Spring 2012 Introduction Computer and Network Security Professor Jaeger www.cse.psu.edu/~tjae ger/cse443-s12/
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Page CMPSC 443 Introduction to Computer and Network Security - Spring 2012 - Professor Jaeger Access Control == Security? • Do the Windows and UNIX access control mechanisms provide security for our systems? – What is security? 2
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Page CMPSC 443 Introduction to Computer and Network Security - Spring 2012 - Professor Jaeger Secure Protection State • Set of all protection states P • Set of secure protection states Q – Subjects access to objects to perform operations – Meets secrecy, integrity, availability goal • Example: Protect access to your public key pair – Only the protection states in which only you can read the private key Fle are secure – Protection states in which only you may write the public key Fle are secure • Problem: Not all processes are necessarily secure – Recall programs running on your behalf Hey, even some programs running on your behalf are not to be trusted with your private key! 3
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Page CMPSC 443 Introduction to Computer and Network Security - Spring 2012 - Professor Jaeger Access Control • Suppose the private key fle For J is object O 1 – Only J can read • Suppose the public key fle For J is object O 2 – All can read, only J can modiFy • Suppose all can read and write From object O 3 • What ʼ s the access matrix? 4 O 1 O 2 O 3 J ? ? ? S 2 ? ? ? S 3 ? ? ?
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Page CMPSC 443 Introduction to Computer and Network Security - Spring 2012 - Professor Jaeger Secrecy • Does the following protection state ensure the secrecy of J ʼ s private key in O 1 ? 5 O 1 O 2 O 3 J R R W R W S 2 N R R W S 3 N R R W
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Page CMPSC 443 Introduction to Computer and Network Security - Spring 2012 - Professor Jaeger Integrity • Does the following access matrix protect the integrity of J ʼ s public key Fle O 2 ? 6 O 1 O 2 O 3 J R R W R W S 2 N R R W S 3 N R R W
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Page CMPSC 443 Introduction to Computer and Network Security - Spring 2012 - Professor Jaeger Trusted Processes • Does it matter if we do not trust some of J ʼ s processes? 7 O 1 O 2 O 3 J R R W R W S 2 N R R W S 3 N R R W
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Page CMPSC 443 Introduction to Computer and Network Security - Spring 2012 - Professor Jaeger Protection vs Security • Protection – Security goals met under trusted processes – Protects against an error by a non-malicious entity • Security – Security goals met under potentially malicious
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cse443-lecture-14-accesscontrol - Access Control CMPSC 443...

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