It can make it impossible to create them from nothing

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Unformatted text preview: capabilities unforgeable? • It can make it impossible to create them from nothing – And only usable by their owner • But it can’t make them uncopyable • So cryptographic capability systems must assume they can be freely copied CS 236 Online Lecture 3 Page 15 Access Control Matrices • A very general access control concept • In principle, ACLs are a 1-D list of who is permitted to access one object • And capabilities are a 1-D list of what one subject can access • Access control matrices are a 2-D description of access rights CS 236 Online Lecture 3 Page 16 Access Control Matrix Example File A User 1 rw User 2 File B r Sysadmin rw r rw CS 236 Online Objects w sr w sr rw configure User 2’s Capabilities sr Guest Subjects Network Printer File B’s ACL Lecture 3 Page 17 Pros and Cons of Access Control Matrices + Makes all access issues explicit and easy to find + Easy to tell who can access a resource, and what resources anyone can access – Matrix very sparse, so inefficient – Hard to achieve good performance • More important conceptually than in implementations CS 236 Online Lecture 3 Page 18 Role Based Access Control • Not really an alternative to ACLs, capabilities, access control matrix • Rather, a more complex way of looking at access control subjects • Commonly used in systems that care about security – Available in Solaris, SE Linux, modern Windows systems CS 236 Online Lecture 3 Page 19 The Idea Behind Role Based Access Control • Eac...
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This document was uploaded on 11/01/2013.

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