An enhanced color visual cryptography scheme based on the binary dragonfly algorithm

ABSTRACT

Visual cryptography is an encryption technique that decomposes a secret image into multiple shares that are digitally ‘overlapped’ based on logical operations to recover the original secret image. Each individual share cannot reveal clues about the secret image. Existing visual cryptography schemes suffer from problems such as pixel expansion, high computational complexity and poor decryption quality. To overcome these problems, we propose a new 2-out-of-2 secret sharing scheme for color images based on the binary dragonfly algorithm. The dragonfly algorithm is used to determine optimal color levels for the encryption process, which leads to reconstructed images with the higher quality upon decryption with minimal effect on the overall computational complexity. The proposed scheme is also non-expansible, whereby the share images are of the same size as the original secret image. This leads to reduced memory requirements as well as improved image quality. We analyze the strength of the proposed scheme based on a standard set of metrics which includes an evaluation of its resistance against cryptanalytic attacks, histogram, correlation, entropy and encryption quality. Results show that the proposed visual cryptography scheme has desired properties such as improved recovered image quality, near-ideal statistical characteristics and fast encryption speed, depicting an improvement over existing schemes.

KEYWORDS:

• Dragonfly algorithm
• encryption
• optimization algorithm
• secret sharing
• security
• visual cryptography

Acknowledgments

This work is supported in part by the Ministry of Education Malaysia under the Fundamental Research Grant Scheme (FRGS), project number FRGS/1/2019/ICT05/USM/02/1.

Disclosure statement

No potential conflict of interest was reported by the author(s).

Additional information

Funding

This work is supported in part by the Ministry of Education Malaysia under the Fundamental Research Grant Scheme (FRGS), project number FRGS/1/2019/ICT05/USM/02/1.

Notes on contributors

Dyala R. Ibrahim

Dyala R. Ibrahim received her B.S. degree in computer technique engineering from Al-Tafila University in 2012, and her M.Sc. degree in security from Al-Zaytoonah University in 2016. She is currently pursuing her Ph.D. at the National Advanced IPv6 Centre, Universiti Sains Malaysia. Her research interests include security, image processing, and artificial intelligence.

Rosni Abdullah

Rosni Abdullah is a professor in computer science at Universiti Sains Malaysia (USM). She obtained her PhD in April 1997 from Loughborough University, United Kingdom specializing in the area of parallel algorithms. Both her bachelors and masters degree in computer science were obtained from Western Michigan University, Kalamazoo, Michigan, U.S.A. Her research areas include parallel & distributed computing and computational biology.

Je Sen Teh

Je Sen Teh is a senior lecturer in computer science at Universiti Sains Malaysia, where he obtained both his PhD and MSc degrees. His research interests include symmetric-key cryptography, cryptanalysis, machine learning and chaos theory.