An Efficient Image Encryption Using a Dynamic, Nonlinear and Secret Diffusion Scheme

تقدم هذه الورقة مخطط نشر سري جديد يسمى نظام التشفير بالمجموعة (RKP) والذي يرتكز على أساس التقليب غير الخطي، الديناميكي والعشوائي لتشفير الصور حسب الكتلة، حيث تعتبر الصور بيانات معينة بسبب حجمها ومعلوماتها، والتي هي ذات طبيعة ثنائية الأبعاد وتتميز بالتكرار العالي والارتباط القوي. أولاً، يتم حساب جدول التقليب وفقًا للمفتاح الرئيسي والمفاتيح الفرعية. ثانيًا، سيتم إجراء خلط وحدات البكسل لكل كتلة سيتم تشفيرها وفقًا لجدول التقليب. بعد ذلك، نستخدم خوارزمية تشفير AES في نظام التشفير عن طريق استبدال التقليب الخطي لمرحلة تحول الصفوف، بالتناوب غير الخطي والسري لمخطط RKP؛ هذا التغيير يجعل نظام التشفير يعتمد على المفتاح السري ويسمح لكلاهما باحترام نظرية شانون الثانية ومبدأ كيرشوف. يوضح تحليل الأمان لنظام التشفير أن مخطط الانتشار المقترح لـ RKP يعزز حصن خوارزمية التشفير، كما يمكن ملاحظته في الانتروبيا والقيم الأخرى التي تم الحصول عليها. النتائج التجريبية التي تحصلنا عليها من خلال التحليل المفصل اثبتت أن التعديل الذي تم إجراؤه عن طريق استخدام التقنية المقترحة يعزز حصن خوارزمية التشفير، كما يمكن ملاحظته في إنتروبيا والقيم الأخرى التي تم الحصول عليها.The growing use of tele This paper presents a new secret diffusion scheme called Round Key Permutation (RKP) based on the nonlinear, dynamic and pseudorandom permutation for encrypting images by block, since images are considered particular data because of their size and their information, which are two-dimensional nature and characterized by high redundancy and strong correlation. Firstly, the permutation table is calculated according to the master key and sub-keys. Secondly, scrambling pixels for each block to be encrypted will be done according the permutation table. Thereafter the AES encryption algorithm is used in the proposed cryptosystem by replacing the linear permutation of ShiftRows step with the nonlinear and secret permutation of RKP scheme; this change makes the encryption system depend on the secret key and allows both to respect the second Shannon’s theory and the Kerckhoff principle. Security analysis of cryptosystem demonstrates that the proposed diffusion scheme of RKP enhances the fortress of encryption algorithm, as can be observed in the entropy and other obtained values. communications implementing electronic transfers of personal data, require reliable techniques and secure. In fact, the use of a communication network exposes exchanges to certain risks, which require the existence of adequate security measures. The data encryption is often the only effective way to meet these requirements. This paper present a cryptosystem by block for encrypting images, as images are considered particular data because of their size and their information, which are two dimensional nature and characterized by high redundancy and strong correlation. In this cryptosystem, we used a new dynamic diffusion technique called round key permutation, which consists to permute pixels of each bloc in a manner nonlinear, dynamic and random using permutation table calculated according to the master key and sub-keys. We use thereafter the AES encryption algorithm in our cryptosystem by replacing the linear permutation of ShiftRows with round key permutation technique; this changing makes the encryption scheme depend on encryption key. Security analysis of cryptosystem demonstrate that the modification made on using the proposed technique of Round Key Permutation enhances the fortress of encryption  algorithm,  as can be observed in the entropy and other obtained values

An Efficient and Secure DNA based Image Encryption Technique

In this paper, an efficient and secure DNA based image encryption technique using hyper chaos Lorenz function is proposed. The technique employs SHA-512 hash of gray scale image and primary key to alter the initial seeds of hyper chaos Lorenz function. Initially, chaotic sequences are generated and redesigned. Then, an image is divided into blocks and randomly shuffled according to the primary key. Further perform circular shift operation over the rows of the shuffled image matrix and index based scrambling operation over the columns. After that, perform dynamic encoding and diffusion based DNA algebraic operation over the encoded DNA sequence and DNA based Key sequence using chaotic sequence. Finally, DNA decoding is employed to convert the diffused dynamic matrix into a ciphered image. The dynamicity of the chaotic sequences makes its extraordinary and contributes to the enhanced security and robustness of the technique. Implementation, security and performance analysis demonstrate that the technique has not only an outstanding encryption effect, but also posses large key space, less pixel correlation, low computation time and successfully resilient to the statistical, differential and brute-force attack. Comparative analysis with other references proves its efficiency and practicability for real time applications