1. Computer Architecture Lab. Hanbit Kim 2008. 12. 9

2. Contents 2/16  Introduction  Motivation  Basic Concept  System Overview  Joint source-channel-authentication  Unequal authenticity protection  Evaluation  Conclusion  Discussion

3. Introduction 3/16  Authenticating multimedia data over wireless networks  Sample products  Medical images  Portraits of criminal suspects

4. Motivation 4/16 11110101010 11100010101 10010100011 Send Sender 11110100010 11100010101 10010100011 Receiver Authentication Fail!! Exe file Sender Multimedia file Receiver Authentication Fail!! Send Packet loss Bit error Is it reasonable?

5. Basic Concept 5/16  Content-awareness framework  Optimizing end-to-end quality  Considering source coding, channel coding and authentication together  Differentiating the importance of packet

6. Basic Concept 6/16 BeforeAfter

7. System Overview 7/16

8. Joint Source-Channel-Authentication 8/16  Optimization  Minimizing end-to-end distortion  Maximizing an authentication probability  D opt = min r s r c (D s,opt (rs) + D ca,opt (E opt (e(r c ),m(r s,r c )), e(r c )))  rs + rc <= 1

9. Joint Source-Channel-Authentication 9/16  Source coding model  R-D relationship  Channel model  e = 1 - (1 - ε d ) lp  Authentication model  Unequal authenticity protection (UAP)

10. Unequal Authenticity Protection 10/16  Signature amortization through hash- chaining (SAHC)  Sign only one packet.

11. Unequal Authenticity Protection 11/16  Authentication probability (AP)  How likely a packet is verifiable.  Authentication graph (AG)

12. Unequal Authenticity Protection 12/16  Multi-layer unequal chaining (MUC)

13. Unequal Authenticity Protection 13/16  Optimal bit allocation 1. Select the number of layers for MUC AG. 2. Select the number of pilot packets 3. Sort and assign the packets to pilot packets according to the weight. 4. Compute the maximum Σ weight * APs.

14. Evaluation 14/16 End-to-end R-D curve

15. Conclusion 15/16  Content-aware stream-level approach  Novel concept of UAP  Joint overall

16. Discussion 16/16  Work on JPEG only  Computation overhead