Visual secret sharing is the method for distributing a secret among a group by using images which can be seen by user groups. Each group holds a share, and with the sufficient amount of shares, the secret can be obtained. When the number of shares is below the threshold, secret would be unable to be acquired. We consider using the quick response (QR) codes, which can be captured by camera phones, to produce the shares for visual secret sharing. With the conventional method, reconstructed QR code can be captured and linked to the webpage while receiving insufficient number of shares, implying the leakage of secret. With our method, sufficient number of shares should be obtained to make the reconstructed QR code possible of delivering the information therein after capturing with the mobile phone camera. Hence, the security with visual secret sharing can be assured.
