1. Two-level controllers hierarchy for a scalable and distributed multicast security protocol
Source: Computers & Security, Vol. 24, No. 5, pp , August 2005
Authors: Heba K. Aslan
Speaker:Pen-Yi Chang

2. Outline
Introduction
Related works
Proposed scheme
Conclusion

3. Introduction
Key distribution
Kg, Ki GM GM

4. Related works(1/2) LKH protocol k1 k1 k2 k3 k3 k4 k5 k6 k7 k7 k8 k9
Broadcast the following:
{k1new}k1, {k3new}k3, {k7new}k7, {k1new, k3new, k7new}k15 k1 k1 k2 k3 k3 k4 k5 k6 k7 k7 k8 k9
k10
k11
k12
k13
k14
k15 U1 U2 U3 U4 U5 U6 U7 U8

5. Related works(2/2) CEKPS protocol kg kg k20 k21 k21 k10 k11 k11 k10
Broadcast kg(new) which encrypted by kg
k21(new) = f(kg(new), k21)
k11(new) = f(kg(new), k11)
k01(new) = f(kg(new), k01) kg kg
k20
k21
k21
k10
k11
k11
k10
k11
k11
k00
k01
k01
k00
k01
k01
k00
k01
k01
k00
k01
U1(k1)
U2(k2)
U3(k3)
U4(k4)
U5(k5)
U6(k6)
U7(k7)
U8(k8)

6. Proposed scheme(1/4) Member join k1-16 k1-16 GM k1-8 k1-8 k9-16 k1-4
SM1
SM2
SM3
SM4
k1-2
k1-2
k3-4
k5-6
k7-8
k9-10
k11-12
k13-14
k15-16 k1 k2 k3 k4 k5 k6 k7 k8 k9
k10
k11
k12
k13
k14
k15
k16 U1 U2 U3 U4 U5 U6 U7 U8 U9
U10
U11
U12
U13
U14
U15
U16
GM generates and broadcasts k1-16(new) which encrypted by k1-16
k1-8(new) = f(k1-16(new), k1-8), k1-4(new) = f(k1-16(new), k1-4), k1-2(new) = f(k1-16(new), k1-2)
GM sends {k1-8(new), k1-16(new)}k1
SM1 sends {k1-4(new), k1-2(new)}k1

7. Proposed scheme(2/4) Member join k1-16 k1-17 k1-8 k9-17 k9-16 k1-4U1 U2 U3 U4 U5 U6 U7 U8 U9
U10
U11
U12
U13
U14
U15
U16
GM generates and broadcasts k1-17 which encrypted by k1-16
K9-17 = f(k1-17, k9-16), k13-17 = f(k1-17, k13-16), k15-17 = f(k1-17, k15-16), and k16-17 = f(k1-17, k16)
GM sends {k1-17, k9-17}k17
SM4 sends {k13-17, k15-17, k16-17 }k17
k16
k17
U16
U17

8. Proposed scheme(3/4) k1-16 k1-17 k1-8 k9-16 k9-17 k1-4 k5-8 k9-12U1 U2 U3 U4 U5 U6 U7 U8 U9
U10
U11
U12
U13
U14
U15
U16
K1-16 = f(k1-17, k1-8), k9-16 = f(k9-17, k9-12), k13-16 = f(k13-17, k13-14), and k15-16 = f(k15-17, k15)
GM sends {k1-16}k9-16, {k9-16}k13-16
SM4 sends {k15-16}k16, {k13-16}k15-16
k16
k17
U16
U17

9. Proposed scheme(4/4) k1-17 k2-17 k1-8 k2-8 k9-17 k1-4 k2-4 k5-8 k9-12U1 U2 U3 U4 U5 U6 U7 U8 U9
U10
U11
U12
U13
U14
U15
k2-17 = f(k1-17, k9-17), k2-8 = f(k1-8, k5-8), k2-4 = f(k1-4, k3-4)
GM sends {k2-17}k2-8, {k2-8}k2-4
SM1 sends {k2-4}k2
Then, in order to maintain the balance of the tree, U17 could be moved to replace U1
k16
k17
U16
U17

10. Conclusion
TLCH protocol enhances the group performance in terms of computation.