Chaotic Visual Cryptography Based Digitized Document Authentication

Abstract

The proposed algorithm concentrates on strengthening the features of digital media by concocting visual cryptography with the aspects of secret data sharing. Besides strengthening the data authentication, integrity, non-repudiation properties, the computational overhead is also reduced in extracting the required keys without any uncertainty. Moreover, effort has been extended to sustain proper signal quality and restrict unauthorized tampering during wireless communication. The first phase of the algorithm describes collection of a digitized signature from a legitimate source; conversion of the pixels of the digitized signature into white or black form based on a threshold comparison result; formation of two shares by representing a pixel value as a combination of two pairs; conversion of the digital cover signal to two distinct frequency levels and casting of one of the shares in high frequency coefficients of the two distinct levels concurrently. The second phase explains appropriate detection of the fabricated share and a user and the proprietary document are authenticated by superimposing the detected share on the second share. The selection of a suitable threshold value to clean the digitized signature and control the share casting intensity helps in considerable reduction of the undesired white noise. The robustness of DWT in narrowband interferences in wireless communication supports its use in the proposed approach. The pseudorandom fabrication position supports visual secret sharing to safeguard the communicating parties from any suspicion. The algorithm can be effectively applied for both born digital as well as digitized document.