Agonistic behavior of captive saltwater crocodile, crocodylus porosus in Kota Tinggi, Johor

Agonistic behavior in Crocodylus porosus is well known in the wild, but the available data regarding this behavior among the captive individuals especially in a farm setting is rather limited. Studying the aggressive behavior of C. porosus in captivity is important because the data obtained may contribute for conservation and the safety for handlers and visitors. Thus, this study focuses on C. porosus in captivity to describe systematically the agonistic behaviour of C. porosus in relation to feeding time, daytime or night and density per pool. This study was carried out for 35 days in two different ponds. The data was analysed using Pearson’s chi-square analysis to see the relationship between categorical factors. The study shows that C. porosus was more aggressive during daylight, feeding time and non-feeding time in breeding enclosure (Pond C, stock density =0.0369 crocodiles/m2) as compared to non-breeding pond (Pond B, stock density =0.3317 crocodiles/m2) where it is only aggressive during the nighttime. Pond C shows the higher domination in the value of aggression in feeding and non-feeding time where it is related to its function as breeding ground. Chi-square analysis shows that there is no significant difference between ponds (p=0.47, χ2= 2.541, df= 3), thus, there is no relationship between categorical factors. The aggressive behaviour of C. porosus is important for the farm management to evaluate the risk in future for the translocation process and conservation of C. porosus generally

Recent Trends in Image Encryption: A Review

Security of multimedia data is gaining acceptance owing to the growth and acceptability of images in various applications and in telecommunication. Encryption is one of the ways to ensure high security of images as they are used in many fields such as in secure medical imaging services, military intelligence, internet and intranet communication, e-banking etc. These images are stored or transmitted through a network; hence the security of such image data is important. In this work, recently developed encryption techniques are studied and analyzed to promote further development of more encryption methods to ensure additional security and versatility. All the techniques reviewed came into existence within the last five years (2011-2015) and are found to be useful for the present day encryption applications. Each technique is unique in its own way, which might be suitable for different applications. As time goes on, new encryption techniques are evolving. Hence, fast and secure conventional encryption techniques will always be needed in applications requiring high rate of security

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

A Simple and Robust Gray Image Encryption Scheme Using Chaotic Logistic Map and Artificial Neural Network

A robust gray image encryption scheme using chaotic logistic map and artificial neural network (ANN) is introduced. In the proposed method, an external secret key is used to derive the initial conditions for the logistic chaotic maps which are employed to generate weights and biases matrices of the multilayer perceptron (MLP). During the learning process with the backpropagation algorithm, ANN determines the weight matrix of the connections. The plain image is divided into four subimages which are used for the first diffusion stage. The subimages obtained previously are divided into the square subimage blocks. In the next stage, different initial conditions are employed to generate a key stream which will be used for permutation and diffusion of the subimage blocks. Some security analyses such as entropy analysis, statistical analysis, and key sensitivity analysis are given to demonstrate the key space of the proposed algorithm which is large enough to make brute force attacks infeasible. Computing validation using experimental data with several gray images has been carried out with detailed numerical analysis, in order to validate the high security of the proposed encryption scheme

A new four-dimensional hyper-chaotic system for image encryption

Currently, images are very important with the rapid growth of communication networks. Therefore, image encryption is a process to provide security for private information and prevent unwanted access to sensitive data by unauthorized individuals. Chaos systems provide an important role for key generation, with high randomization properties and accurate performance. In this study, a new four-dimensional hyper-chaotic system has been suggested that is used in the keys generation, which are utilized in the image encryption process to achieve permutation and substitution operations. Firstly, color bands are permuted using the index of the chaotic sequences to remove the high correlation among neighboring pixels. Secondly, dynamic S-boxes achieve the principle of substitution, which are utilized to diffuse the pixel values of the color image. The efficiency of the proposed method is tested by the key space, histogram, and so on. Security analysis shows that the proposed method for encrypting images is secure and resistant to different attacks. It contains a big key space of (2627) and a high sensitivity to a slight change in the secret key, a fairly uniform histogram, and entropy values nearby to the best value of 8. Moreover, it consumes a very short time for encryption and decryption

Image encryption under spatial domain based on modify 2D LSCM chaotic map via dynamic substitution-permutation network

Image encryption has become an important application aspect of information security. Most attempts are focused on increasing the security aspect, the quality of the resulting image, and the time consumed. On the other hand, dealing with the color image under the spatial domain in this filed is considered as another challenge added to the proposed method that make it sensitivity and difficulty. The proposed method aims to encode a color image by dealing with the main color components of the red (R), green (G), and blue (B) components of a color image to strengthen the dependence of each component by modifying a two dimensional logistic- sine coupling map (2D- LSCM). This is to satisfy the statistical features and reduce time-consumption, and benefit from a mixing step of the second of advanced encryption standard (AES) candidates (serpent block cipher) and modified it to achieve in addition of confusion and diffusion processes. The experimental results showed that our proposed method had the ability to resist against statistical attacks and differential attacks. It also had a uniform histogram, a large key space, complex and faster, closer Shannon entropy to 8, and low correlation values between two adjacent pixels compared with other methods