Protection matrix - Revision history

Kosik: missing indefinite article in the title of the section

2009-09-08T09:08:53Z

missing indefinite article in the title of the section

New page

== Definition ==

One way how to capture the [[Subject, object, operation and permission|permissions of subjects to perform various operations with objects]] is to use a large matrix where:
* rows correspond to particular subjects
* columns correspond to particular objects
and the context of each cell determines what operations on a particular object are permitted for a particular subject.

== An artificial example ==

If:
* we have only three different subjects (1, 2 and 3)
* eight different objects (six files and a printer and a mixer)
* we recognize three different operations with objects (read, write and execute)
then one possible protection matrix may be:

[[Image:Protection matrix1.png]]

The matrix determines which operations (R = read, W = write, X = execute) with particular objects are allowed for particular subjects.

It is not very usual to actually store permissions in the form of a 2-dimensional array as shown in the figure above but there are such systems which do so. Usually, the set of subjects and the set of objects are small and immutable.

== Real world examples ==

* [[Protection matrixes in Minix]]

Kosik: Add a link to a real world example of this (basic) concept.

2009-06-20T15:39:28Z

Add a link to a real world example of this (basic) concept.

←Older revision		Revision as of 15:39, 20 June 2009
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	and the context of each cell determines what operations on a particular object are permitted for a particular subject.		and the context of each cell determines what operations on a particular object are permitted for a particular subject.

-	== ~~Example~~ ==	+	== Artificial example ==

	If:		If:
Line 19:		Line 19:

	It is not very usual to actually store permissions in the form of a 2-dimensional array as shown in the figure above but there are such systems which do so. Usually, the set of subjects and the set of objects are small and immutable.		It is not very usual to actually store permissions in the form of a 2-dimensional array as shown in the figure above but there are such systems which do so. Usually, the set of subjects and the set of objects are small and immutable.
		+
		+	== Real world examples ==
		+
		+	* [[Protection matrixes in Minix]]

Kosik at 05:20, 17 June 2009

2009-06-17T05:20:24Z

←Older revision		Revision as of 05:20, 17 June 2009
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	[[Image:Protection matrix1.png]]		[[Image:Protection matrix1.png]]
		+
		+	The matrix determines which operations (R = read, W = write, X = execute) with particular objects are allowed for particular subjects.

	It is not very usual to actually store permissions in the form of a 2-dimensional array as shown in the figure above but there are such systems which do so. Usually, the set of subjects and the set of objects are small and immutable.		It is not very usual to actually store permissions in the form of a 2-dimensional array as shown in the figure above but there are such systems which do so. Usually, the set of subjects and the set of objects are small and immutable.

Kosik: /* Example */

2009-06-16T19:59:59Z

Example

←Older revision		Revision as of 19:59, 16 June 2009
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	[[Image:Protection matrix1.png]]		[[Image:Protection matrix1.png]]

-	It is not very usual to actually store permissions in the form of a 2-dimensional array as shown in the figure above but there are such systems which do so. Usually, the set of subjects and the set of objects are small and immutable~~. See [[protection in Minix 3.1.1]]~~.	+	It is not very usual to actually store permissions in the form of a 2-dimensional array as shown in the figure above but there are such systems which do so. Usually, the set of subjects and the set of objects are small and immutable.

Kosik at 15:18, 16 June 2009

2009-06-16T15:18:42Z

←Older revision		Revision as of 15:18, 16 June 2009
Line 10:		Line 10:
	If:		If:
	* we have only three different subjects (1, 2 and 3)		* we have only three different subjects (1, 2 and 3)
-	* eight different objects (six files and a printer and a ~~plotter~~)	+	* eight different objects (six files and a printer and a mixer)
	* we recognize three different operations with objects (read, write and execute)		* we recognize three different operations with objects (read, write and execute)
	then one possible protection matrix may be:		then one possible protection matrix may be:

Kosik: /* Example */

2009-06-16T14:12:02Z

Example

←Older revision		Revision as of 14:12, 16 June 2009
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	[[Image:Protection matrix1.png]]		[[Image:Protection matrix1.png]]

-	It is not very usual to actually store ~~the~~ permissions in the form of a 2-dimensional array as shown in the figure above but there are such systems. Usually, the set of subjects and the set of objects are small and immutable. See [[protection in Minix 3.1.1]].	+	It is not very usual to actually store permissions in the form of a 2-dimensional array as shown in the figure above but there are such systems which do so. Usually, the set of subjects and the set of objects are small and immutable. See [[protection in Minix 3.1.1]].

Kosik at 14:11, 16 June 2009

2009-06-16T14:11:05Z

←Older revision		Revision as of 14:11, 16 June 2009
Line 15:		Line 15:

	[[Image:Protection matrix1.png]]		[[Image:Protection matrix1.png]]
		+
		+	It is not very usual to actually store the permissions in the form of a 2-dimensional array as shown in the figure above but there are such systems. Usually, the set of subjects and the set of objects are small and immutable. See [[protection in Minix 3.1.1]].

Kosik: /* Definition */

2009-06-16T12:41:39Z

Definition

←Older revision		Revision as of 12:41, 16 June 2009
Line 5:		Line 5:
	* columns correspond to particular objects		* columns correspond to particular objects
	and the context of each cell determines what operations on a particular object are permitted for a particular subject.		and the context of each cell determines what operations on a particular object are permitted for a particular subject.
		+
		+	== Example ==
		+
		+	If:
		+	* we have only three different subjects (1, 2 and 3)
		+	* eight different objects (six files and a printer and a plotter)
		+	* we recognize three different operations with objects (read, write and execute)
		+	then one possible protection matrix may be:
		+
		+	[[Image:Protection matrix1.png]]

Kosik at 12:19, 16 June 2009

2009-06-16T12:19:10Z

←Older revision		Revision as of 12:19, 16 June 2009
Line 5:		Line 5:
	* columns correspond to particular objects		* columns correspond to particular objects
	and the context of each cell determines what operations on a particular object are permitted for a particular subject.		and the context of each cell determines what operations on a particular object are permitted for a particular subject.
-
-	~~== An artificial example ==~~
-
-	~~If:~~
-	* we have only three different subjects (1, 2 and 3)
-	* eight different objects (six files and a printer and a mixer)
-	* we recognize three different operations with objects (read, write and execute)
-	~~then one possible protection matrix may be:~~
-
-	~~[[Image:Protection matrix1.png]]~~
-
-	~~The matrix determines which operations (R = read, W = write, X = execute) with particular objects are allowed for particular subjects.~~
-
-	It is not very usual to actually store permissions in the form of a 2-dimensional array as shown in the figure above but there are such systems which do so. Usually, the set of subjects and the set of objects are small and immutable.
-
-	~~== Real world examples ==~~
-
-	* [[Protection matrixes in Minix]]