Secret image sharing with separate shadow authentication ability

Secret image sharing (SIS) is attracting increasing attention due to its wide application to the distributed storage of digital images in a cloud and the importance of digital images. Shadow authentication plays an important role in the practical application of SIS. However, most SIS schemes with shadow authentication ability embed each shadow into a cover image using an existing information hiding technique, which leads to high generation and recovery (authentication) complexity and pixel expansion. In this paper, we propose an SIS scheme for a (k,n) threshold with a separate shadow authentication ability based on SIS itself rather than information hiding through applying visual secret sharing (VSS) to polynomial-based SIS by using a screening operation. The proposed scheme has low generation and recovery (authentication) complexity and no pixel expansion with a separate shadow authentication ability. In addition, it achieves lossless recovery without auxiliary encryption. We validate the proposed scheme by means of illustrations, theoretical analyses and comparisons. •SIS with a separate shadow authentication ability is proposed.•The secret image is losslessly recovered without auxiliary encryption.•It has low recovery (authentication) complexity and no pixel expansion.