Indonesian Journal of Electrical Engineering and Computer Science Vol. 28, No. 1, October 2022, pp. 201~208 ISSN: 2502-4752, DOI: 10.11591/ijeecs.v28.i1.pp201-208  201 Journal homepage: http://ijeecs.iaescore.com Binary decomposition-based Image cipher algorithm with flexible method for key construction Salim Muhsin Wadi 1 , Huda Hussein Abed 1 , Nada Taher Malik 2 , Ahmed Taha Abdullsadah 1 1 Department of Communication Techniques Engineering, Engineering Technical College-Najaf (ETCN), Al-Furat Al-Awsat Technical University (ATU), Kufa, Iraq 2 Computer Center, Al-Dewaniyah Technical Institute, Al-Furat Al-Awsat Technical University (ATU), Kufa, Iraq Article Info ABSTRACT Article history: Received Mar 30, 2022 Revised Jul 28, 2022 Accepted Aug 5, 2022 Image security is still one of the important fields in multimedia processing because it’s used in our daily lives. Watermarking, steganography, and ciphering are three directions to keep an image secret. Encryption defined as the process of changing information (which called plaintext) into an unreadable secret format (which called cipher-text). A new ciphering algorithm based on binary decomposition and binary codes conversion is proposed in this paper. The key is constructed in a flexible way based on the size of a secret image using some logical operations to increase the security levels. Three test images in different sizes were used to evaluate the performance of the proposed algorithm. The results of the visual scene and statistical factors proved that the suggested method was ciphering the image with high security. The proposed work was validated to confirm its effectiveness. As conclusions, the uses of decomposition and simple binary operations have given high-level image security. Also, key construction is an important step to face several types of attackers. Keywords: ASCII codes pixels Binary codes decomposition Confidential images Secret keys Smart key constructions This is an open access article under the CC BY-SA license. Corresponding Author: Salim Muhsin Wadi Department of Communication Techniques Engineering, Engineering Technical College-Najaf Al-Furat Al-Awsat Technical University Najaf, Iraq Email: coj.sal@atu.edu.iq 1. INTRODUCTION Multi-media fast developing in last years required improving the processing techniques for video, audio and image files. Digital image was one of the interest fields in the multi-media word that need to enhance its tools and techniques in the several directions such as enhancement, recognition, security, comparison, segmentation, etc. Today, keeping images secure become one of the complicated challenges that facing security technicians in transferring and storing images operations [1]-[5]. Image encryption techniques play a important role in multimedia applications to secure and authenticate digital images. In general, the multimedia security techniques are classified into encryption and hiding. Encryption techniques effectively protect multimedia information by converting it into an unknown form by the adversary [6]. Since the 16th century, encryption techniques appeared and remained constantly evolving in parallel line with hacking techniques improving. Image encryption techniques classified depends several vactors to multiple techniques for example: based on representation to frequency or spatial domain, based on key to private or public key, the data size that encrypted at a time to block or stream [7]-[10]. Encryption in the spatial domain is more effective than frequency domain in terms of simplicity and computational cost, consequently encryption in the spatial domain is more compatible with image encryption.