Title: Degradation and encryption for outsourced PNG images in cloud storage

Authors: Ying Wang; Jiali Du; Xiaochun Cheng; Zheli Liu; Kai Lin

Addresses: South China Institute of Software Engineering, Guangzhou University, Guangdong, China ' Guangzhou Vocational School of Finance and Economics, Guangdong, China ' Department of Computer Science, Middlesex University, London NW4 4BT, UK ' College of Computer and Control Engineering, Nankai University, Tianjin, China ' Space Star Technology Co., Ltd., Beijing, China

Abstract: In cloud storage environment, users frequently store images and retrieve them by personal device, including mobile phones. However, the content of outsourced images will be leaked to the cloud server, which is not trusted by users. To protect the privacy of sensitive images, this paper proposes format-compliant degradation and encryption method for Portable Network Graphics (PNG). More specifically, for PNG degradation, improved prefix method and noise generation methods are developed. Furthermore, for PNG encryption, a modified generalised-Feistel method is developed. Finally, our security analysis demonstrates that the proposed scheme is secure. Our experiment results also show that the scheme is efficient and practical.

Keywords: image privacy; format compliant encryption; format preserving encryption; cloud storage; PNG images; portable network graphics; cryptography; image degradation; outsourcing; cloud computing; image security.

DOI: 10.1504/IJGUC.2016.073773

International Journal of Grid and Utility Computing, 2016 Vol.7 No.1, pp.22 - 28

Received: 21 Apr 2014
Accepted: 22 Jul 2014
Published online: 22 Dec 2015 *

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