Question

(4 pts) Say that a system has 10 users, each of which has 200 files in their home directory. Each user should have read and write access to every file in their own home directory.

If this policy were expressed as a DAC matrix, how many nonempty entries would the matrix need to have?

Express this policy as a single if-then rule, such as might be used in an Attribute-based Access Control (ABAC) system.

PLEASE GIVE ONE WORD OR ONE LINE ANSWERS AND DO NOT TYPE ESSAYS. THANK YOU

Answer 1

Lets consider a 2D Matrix where columns represents the users and rows denote the Files that each user have access to:-

Here R/W means that the user has Read/Write access to a particular File in his home directory

	USER1	USER2	USER3	USER4	USER5	USER6	USER7	USER8	USER9	USER10
FILE1	R/W	R/W	R/W		...	....	....	...	....	...
FILE2	R/W			R/W
FILE3		R/W		R/W
...
FILE200		R/W	R/W

How many nonempty entries would the matrix need to have?
The number of non-empty entries will be determined whether a particular user has Read/Write access for that particular file.

Express this policy as a single if-then rule, such as might be used in an Attribute-based Access Control (ABAC) system.

if (USER_ACCESS [0][0] == 'R/W') then .....

else if (USER_ACCESS[0][0] == ' ') then ....

Please let me know in case of any clarifications required. Thanks!