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Unit 8: System Protection

have been used by them to restrict the access of downloaded Java applets. One approach relies Notes
on the fact that separate class loader objects are used to load local and remote code and that
the stack frame of each method points to the object that loaded it. As a result, when a protected
method is called, the browser can provide restricted access if the stack contains a method that
was called (directly or indirectly) by downloaded code.
The other approach relies on the fact that the loader can determine the name space of downloaded
code. It creates restrictive proxy classes for the protected classes, and makes sure that downloaded
code sees the proxy classes instead of the protected classes.
In computer science, an Access Control Matrix or Access Matrix is an
abstract, formal security model of protection state in computer systems, that
characterizes the rights of each subject with respect to every object in the
system.

Self Assessment

Multiple choice questions:
1. What is system protection?

( a) System protection is a feature that regularly creates and saves information about your
computer’s system files and settings.
( b) System protection is a program that regularly creates and saves information about
your computer’s system files and settings.

( c) System protection is a application that regularly creates and saves information about
your computer’s system files and settings.

( d) None of these.
2. Access matrix is defined as .................... .

( a) a model of protection mechanisms in computing systems.

( b) is a matrix that shows the protection level across several domains.
( c) work flow management.

( d) All of the above.

3. Where we can implement the Access Matrix?
( a) Network-wide capabilities.

( b) Replicated access lists.

( c) Application-Defined Objects.
( d) All of the above.

8.3 Access Control

This section introduces concepts, common terms, and basic (popular) policies and models of
access control. The contents of this section are referenced throughout the document.

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