Improved Visual Secret Sharing Scheme for QR Code Applications Source: IEEE Transactions on Information Forensics and Security. 2018 Mar 23. Authors: Yuqiao Cheng, Zhengxin Fu, and Bin Yu Speaker: Huang Peng-Cheng Date: 1/14/2019 Hefei Electronic Engineering Institute, Hefei 230037, China

Outline Introduction Related works Proposed scheme Comparisons Conclusions Comments

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

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. 409-425. Springer, Cham, 2016.

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

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

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.

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)

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

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

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

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}}

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

Comparisons (1/4)

Comparisons(2/4)

Comparisons (3/4)

Comparisons (4/4)

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

Comments higher security?