1. Efficient Key Distribution Schemes for Secure Media Delivery in Pay-TV Systems
Authors: Y.L. Huang, S.P. Shieh, F.S. Ho, and J.C. Wang
Source: accepted for publication on IEEE Transactions on Multimedia
Data: 2003/06/19
Speaker: Iuon-Chang Lin

2. Service Provider /Broadcaster (SP)
Set-top-box
(STB)
Service Request
Service Response
Customer
Service Provider /Broadcaster (SP)
Television
Subscription channel :
a subscriber subscribes a channel for a period of a time.
Pay-per-view channel :
a subscriber pays for each single program

3. Key Distribution Scheme for Subscription Channel Protection
Goal : only authorized subscribers can descramble the programs correctly
Four-key Hierarchy :
CW: Control Word
AK: Authentication Key
AK={ak1, ak2, … ,akm}
DK: Distribution Key
DK={dk1, dk2, … ,dkm}
SK: Secret Key

4. Subscription Channel Groups
G1ABC G2BBS G3ESPN
G4HBO G5Discovery G6 Sunmovie
. . .
SG1: {ABC, HBO, Discovery}
SG2: {BBC, Sunmovie, Discovery}
SGn: {ESPN, HBO, Discovery}
AK1, DK1
AK2, DK2
AKn, DKn
SG1={G1, G4, G5}
AK1={ak1, ak2, ak3, ak4, ak5, ak6}
DK1={dk1, dk2, dk3, dk4, dk5, dk6}

5. Subscription Channel Based Protocol-Initial Phase
ak1=Ddk1
ak2=ak1dk2
ak3=ak2dk3
ak4=ak3dk4

6. Subscription Channel Based Protocol-Update Phase

7. Key Distribution Scheme for Pay-Per-View Channel Protection
Three-key Hierarchy :
CW: Control Word
AK: Authentication Key
AK={ak1, ak2, … ,akm}
SK: Secret Key

8. PPV Based Protocol

9. Comparisons (1) Comparison in terms of number of message transmissions
M: # of subscriber groups
P: # of channel groups
K: max # of subscribers in each subscriber group in PPV channel

10. Comparison in terms of computational cost
Comparisons (2)
Comparison in terms of computational cost
M: # of subscriber groups
P: # of channel groups
K: max # of subscribers in each subscriber group in PPV channel

11. Conclusions