1. Safety in Access Control Take-Grant (best viewed in slide-show mode)
Ravi Sandhu
Laboratory for Information Security Technology
George Mason University

2. The Take-Grant Model (late 70’s, early 80’s)B t
A/t
(a) A/t Є dom(B) A B g
B/g
Original graph representation, late 70’s
(b) B/g Є dom(A)

3. The Take-Grant Model (late 70’s, early 80’s)B t
A/t
(a) A/t Є dom(B) A B g
B/g
Lockman-Minsky representation, 1982
(b) B/g Є dom(A)

4. Creation in Take-Grant
A’/tg
A’/tg A A t g t g A’ A’
(a) The Original View
(b) The Lockman-Minsky View

5. Reversal of Take-Grant Flow: case tB t
A’/tg
A/t
A’/tg
A/t t t g g A’

6. Reversal of Take-Grant Flow: case gB g
B/g
B/g
A’/tg
A’/tg t t g g A’

7. Reversal of Grant-Only FlowB g
B/g
A’/g
B/g
A/g
A’/g g g g g
A/g
B/g
A/g A’

8. Non-Reversal of Take-Only FlowB t
A’/t
A/t
A’/t
A/t t t t
A/t A’

9. Shortening of Take-Only FlowsB C t t
A/t
B/t
A/t
B/t

10. Summary Take-Grant, Grant only
Disconnected islands of completely connected subjects with total sharing of rights within each island and no sharing across islands
Take-only
Original topology of flows is preserved, but existing paths can be shortened to a direct edge
Send-receive
Requires send and receive rights
Similar to take-only in preserving original topology of flows, but existing paths cannot always be shortened to a single edge

11. Exercise
Express take-grant, grant-only, take-only and send-receive in the HRU model
Are these constructions
Mono-conditional
Bi-conditional
Mono-operational