Download presentation

Presentation is loading. Please wait.

Published byKaitlyn Coleman Modified over 3 years ago

1
© Ravi Sandhu www.list.gmu.edu HRU and TAM Ravi Sandhu Laboratory for Information Security Technology George Mason University www.list.gmu.edu sandhu@gmu.edu

2
© 2004 Ravi Sandhu www.list.gmu.edu 2 The Access Matrix Model, Lampson 1971

3
© 2004 Ravi Sandhu www.list.gmu.edu 3 The HRU (Harrison-Ruzzo-Ullman) Model, 1976 Ur w V F G r

4
© 2004 Ravi Sandhu www.list.gmu.edu 4 The HRU (Harrison-Ruzzo-Ullman) Model, 1976 Ur w V F r w own G r

5
© 2004 Ravi Sandhu www.list.gmu.edu 5 The HRU (Harrison-Ruzzo-Ullman) Model, 1976 Ur w V F r w own G r r

6
© 2004 Ravi Sandhu www.list.gmu.edu 6 HRU Commands and Operations command α(X1, X2,..., Xk) if rl in (Xs1, Xo1) and r2 in (Xs2, Xo2) and ri in (Xsi, Xoi) then op1; op2; … opn end enter r into (Xs, Xo) delete r from (Xs, Xo) create subject Xs create object Xo destroy subject Xs destroy object Xo

7
© 2004 Ravi Sandhu www.list.gmu.edu 7 HRU Examples

8
© 2004 Ravi Sandhu www.list.gmu.edu 8 HRU Examples

9
© 2004 Ravi Sandhu www.list.gmu.edu 9 HRU Examples

10
© 2004 Ravi Sandhu www.list.gmu.edu 10 HRU Examples

11
© 2004 Ravi Sandhu www.list.gmu.edu 11 The Safety Problem Given initial state protection scheme (HRU commands) Can r appear in a cell that exists in the initial state and does not contain r in the initial state? More specific question might be: can r appear in a specific cell [s,o]

12
© 2004 Ravi Sandhu www.list.gmu.edu 12 The Safety Problem Initial state: r in (o,o) and nowhere else

13
© 2004 Ravi Sandhu www.list.gmu.edu 13 Safety is Undecidable in HRU

14
© 2004 Ravi Sandhu www.list.gmu.edu 14 TAM adds types to HRU

15
© 2004 Ravi Sandhu www.list.gmu.edu 15 TAM adds types to HRU

16
© 2004 Ravi Sandhu www.list.gmu.edu 16 TAM commands

17
© 2004 Ravi Sandhu www.list.gmu.edu 17 TAM primitive operations

18
© 2004 Ravi Sandhu www.list.gmu.edu 18 TAM operations: enter and delete

19
© 2004 Ravi Sandhu www.list.gmu.edu 19 TAM operations: create and destroy

20
© 2004 Ravi Sandhu www.list.gmu.edu 20 TAM operations: create and destroy

21
© 2004 Ravi Sandhu www.list.gmu.edu 21 The Safety Problem TAM has much stronger safety properties than HRU

Similar presentations

OK

DIVIDING INTEGERS 1. IF THE SIGNS ARE THE SAME THE ANSWER IS POSITIVE 2. IF THE SIGNS ARE DIFFERENT THE ANSWER IS NEGATIVE.

DIVIDING INTEGERS 1. IF THE SIGNS ARE THE SAME THE ANSWER IS POSITIVE 2. IF THE SIGNS ARE DIFFERENT THE ANSWER IS NEGATIVE.

© 2017 SlidePlayer.com Inc.

All rights reserved.

Ads by Google