1. Improved Visual Secret Sharing Scheme for QR Code Applications
Source: IEEE Transactions on Information Forensics and Security Mar 23.
Authors: Yuqiao Cheng, Zhengxin Fu, and Bin Yu
Speaker: Huang Peng-Cheng
Date: 1/14/2019
Hefei Electronic Engineering Institute, Hefei , China

2. Outline Introduction Related works Proposed scheme Comparisons
Conclusions
Comments

3. Introduction(1/1) --visual cryptography scheme(VCS)

4. Related works(1/2) Chow et al.’s scheme
[26] Chow, Yang-Wai, Willy Susilo, Guomin Yang, James G. Phillips, Ilung Pranata, and Ari Moesriami Barmawi. "Exploiting the error correction mechanism in QR codes for secret sharing." In Australasian Conference on Information Security and Privacy, pp Springer, Cham, 2016.

5. Related works(2/2) Chow et al.’s scheme
QR code version: 4-H.
4 blocks
Each block: 25 codewords,
ECC: 8 codewords
Example 1: (10,10)-threshold SS

6. Proposed scheme (1/8) -- Enhanced (n, n) sharing method (1/1)

7. Proposed scheme (2/8) --(k, n) sharing method (1/7)
(3,5)-threshold secret sharing
1,2,3,1,2,4,1,2,5,1,3,4,1,3,5,1,4,5,2,3,4,2,3,5,2,4,5,3,4,5
To improve the sharing efficiency, this paper presents two division algorithms.

8. Proposed scheme (3/8) --(k, n) sharing method (2/7)
Division Algorithm 1 (1/3)
Example 3. By applying Division Algorithm 1, k-participant subsets of (3,5) access structure are divided.
Reduce (3,5) to (3,3)

9. Proposed scheme (4/8) --(k, n) sharing method (3/7)
Division Algorithm 1 (2/3)

10. Proposed scheme (5/8) --(k, n) sharing method (4/7)
Division Algorithm 1 (3/3)

11. Proposed scheme (6/8) --(k, n) sharing method (5/7)
Division Algorithm 2 (1/3)

12. Proposed scheme (7/8) --(k, n) sharing method (6/7)
Division Algorithm 2 (2/3)
Example 4. The QR codes in this example are the same as in the previous examples. We divide the k-participant subsets of the (4,5) access structure using Division Algorithm 2.
M0 = {{1,2,3,4},{1,2,3,5},{1,2,4,5},{1,3,4,5},{2,3,4,5}}

13. Proposed scheme (8/8) --(k, n) sharing method (7/7)
Division Algorithm 2 (3/3)

14. Comparisons (1/4)

15. Comparisons(2/4)

16. Comparisons (3/4)

17. Comparisons (4/4)

18. Conclusions Meaningful shares => the decodable of QR code.
Higher security
More flexible access structures. Extended the access structure from (n, n) to (k, n)
The computational cost of our work is much smaller than that of the previous studies

19. Comments
higher security?