1. Structural Digital Signature for Image Authentication: An Incidental Distortion Resistant Scheme
Source: IEEE Transactions on Multimedia, Vol. 5, No. 2, pp , Authors: Chun-Shien Lu and Hong-Yuan Mark Liao
Reporter: Jen-Bang Feng

2. Outline Digital Signature Scenarios During the Authentication Process
SDS Based on Interscale Relation of Wavelet Coefficients
Ex. Results
Discussions
Conclusions

3. Examples of Digital Signature

4. Possible Scenarios During the Authentication Process

5. Parent-children Pair

6. Structural Digital Signature (SDS)
Parent-children pair in Wavelet Trans.
SDS(I):
0 <= i,j <= 1, o is the position index

7. Structural Digital Signature (SDS)
Symbol I:
p > 0, c > 0
Symbol II:
p > 0, c < 0
Symbol III:
p < 0, c > 0
Symbol IV:
p < 0, c < 0
Record the Symbols as the signature

8. Verification
Completeness of SDS:

9. Ex. Results
22~4 scales
when σ = 256
22~4 scales
when σ = 128

10. Ex. Results
22~4 scales
when σ = 256
22~4 scales
when σ = 128

11. Ex. Results

12. Ex. Results

13. Ex. Results

14. Discussions Num. of scales Complexity False Positive & False Negative
Relation between σ and robustness
Relation between σ and sensitivity
If image intensity is changed
If the selected parent-children pair are known and changed

15. Conclusions
Threshold value determines the size of the authentication message.
Malicious tampering is distinguished from incidental modifications.
Tampered regions are localized.
The recovery of the tampered region is not provided.