Color image share cryptography: a novel approach

Issue title: Special Section: Intelligent, Smart and Scalable Cyber-Physical Systems

Guest editors: V. Vijayakumar, V. Subramaniyaswamy, Jemal Abawajy and Longzhi Yang

Article type: Research Article

Authors: Hasnat, Abul | Barman, Dibyendu^{; *} | Sarkar, Suchintya

Affiliations: Government College of Engineering and Textile Technology, Berhampore, WB, India

Correspondence: [*] Corresponding author. Dibyendu Barman, Government College of Engineering and Textile Technology, Berhampore, WB, India. E-mail: [email protected].

Abstract:  Shared visual cryptography is a method to protect image-based secrets where an image is kept as multiple shares having less computational decoding process. Steganography is a technique to hide secret data in some carrier like-audio, image etc. Steganography technique is categorized into four categories. i) Spatial Domain Technique- Image pixel values are converted into binary and some of the binary values changed to hide secret data. ii) Transform Domain Technique- the message is hidden in cover image and then it is transformed in the frequency domain. iii) Distortion Technique-information is stored by changing the value of the pixel. iv)Visual Cryptography Technique-Image is broken into two or more parts called shares. This article proposes a hybrid visual crypto-steganography approach which exploits the advantages of both approaches to protect image based secret in communication. Most of the visual cryptography is applied on black and white images but the proposed method can be applied directly on color images having three channels. This method does not change the image size. Also an exact replica of original image can be reconstructed therefore this process does not result in image quality degradation. This article proposes novel color image share cryptography where seven shares are generated from one color image (correlated/de-correlated color space). These shares are sent to the receiver and original image is reconstructed using all those shares. Share generation and image reconstruction is based on simple operation like pixel shuffling, reversing binary string of the image information, ratio of pixel intensity values. Row key matrix and column key matrix are generated using random function. Pixel positions are shuffled using these two key matrixes. These seven shares namely Row Key, Column Key, Remainder matrix, Quotient matrix, R ratio matrix, G ratio matrix and B ratio matrix are generated. Then Row key matrix, Column key matrix, Remainder matrix, Quotient matrix and three ratio matrices are hidden into separate cover images by LSB encoding technique and sent over the network. Receiver can reconstruct the image if all shares are available only. The proposed method is applied on standard images in the literature and images captured using standard digital camera. Comparison study with existing methods shows that the proposed method performs better in terms of NIST metrics. The method has many applications in the area of visual cryptography, shared cryptography, image based authentication etc.

Keywords: Binary image, Cryptography, GCD, image decryption, image encryption, image security, quotient, remainder, shared visual cryptography, steganography

DOI: 10.3233/JIFS-179002

Journal: Journal of Intelligent & Fuzzy Systems, vol. 36, no. 5, pp. 4491-4506, 2019