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Top1. Introduction
Digitalization of our common e-life made any multimedia communication and storage in risk due to illegitimate security breaches. Any e-data usage within insecure communication channels or storage is vulnerable to attacks concerning confidentiality, integrity, and availability (CIA), as main driving force for enhancing IT security urgency (Gutub et al., 2019). E-multimedia files run almost all industries requiring ongoing authentic setting guaranteeing safe delivery and storage of all e-data (Alharthi & Gutub, 2017). Digital images, as focus of our research, is the most widespread media type used needing proper security (Gutub et al., 2019). Therefore, e-image encryption is compulsory for protecting privacy as well as preventing undesired manipulation, which is provided via image symmetric cryptography via confirmed agreed-upon key passwords (Alharthi & Gutub, 2017). Image encryption is mandatory to secure its content as more breaches are occurring continuously remarking uncertain and/or untrusted e-media formation (Gutub, 2011). Cryptography provides encryption of image e-formation to cipher-image (Al-Otaibi & Gutub, 2014) via diverse math formulation, i.e. to change it into unusable data (Gutub & Tenca, 2004). The security process necessitates password key symmetrically used the same for image encryption and decryption providing needed security (Al-Juaid & Gutub, 2019). Therefore, many crypto approaches designed for image encryption are not coping to today’s technology improvements needing to be revisited. For example, original AES famous crypto is becoming to lose from its efficiency for image encryption, due to data patterns construction, insisting on special AES tuning remarking many manipulations (Saha et al., 2018). In general, encryption can be performed via transposition or substitution as well as combination of both. The transposition technique relocates pixels position shuffled based on positioning rules, as shown simplified in Figure 1. The substitution process is used to replace pixel values in a way that can be retrieved uniquely via password key whenever needed. Both methods accomplish the security goals of confusion and diffusion adhering to cryptography secrecy attitude (Al-Juaid & Gutub, 2019). Image crypto approaches can be commonly understood via three models, namely permuting, substituting, and combination of both. The permuting pixels relocate the pixels spots via reordering, as illustrated in Figure 2. The substituting performs replacing reformation via key generator hiding originality. The combination of permutation and substitution can be interesting benefitting from advantages of both (Banthia & Tiwari, 2013).
This paper deals with symmetric encryption as process uses password key as same for encryption and decryption (Gutub & Tenca, 2004). Our crypto modelling uses the password key to ignite the pseudo-random number generator (PRNG) to produce secret sequence stream to be involved mathematically with the image pixels to form intended encryption (Banthia & Tiwari, 2013). This PRNG random sequence needs to enjoy unpredictability and randomness, as main trusting features to be considered (Sivakumar & Devi, 2017).
Figure 1.
Transposition articulation