Distortion-free multiple images sharing scheme with universal share

Recently, Fang and Lin proposed a multiple images sharing system with a universal share. This universal share can be usedfor a company's organizer to attend the recovery meeting of any shared images. Since the organizer only needs to keep the unique share, it reduces the difficulties ofthe share management ofthe organizer. However, the universal share is embedded into a secret by the least-significant-bits (LSB) substitution method before evaluating all the shares of the secret. The secret image becomes a distortion image. The original secret cannot be reconstructed without loss. In this paper, we present a distortionfree sharing schemefor the sharing ofmultiple images. Instead of using LSB to embed a universal share, all the bits ofthe secret image and the universal share are used to generate the coefficients of sharing polynomials. Moreover, this paper employs the Galois Field GF(2⁸) instead of GF(251). Since all the information of the security image is hiding in those polynomials, the original secret can be revealed without any distortion.