Chosen-plaintext attack of an image encryption scheme based on modified permutation-diffusion structure

Since the first appearance in Fridrich's design, the usage of permutation-diffusion structure for designing digital image cryptosystem has been receiving increasing research attention in the field of chaos-based cryptography. Recently, a novel chaotic Image Cipher using one round Modified Permutation-Diffusion pattern (ICMPD) was proposed. Unlike traditional permutation-diffusion structure, the permutation is operated on bit level instead of pixel level and the diffusion is operated on masked pixels, which are obtained by carrying out the classical affine cipher, instead of plain pixels in ICMPD. Following a \textit{divide-and-conquer strategy}, this paper reports that ICMPD can be compromised by a chosen-plaintext attack efficiently and the involved data complexity is linear to the size of the plain-image. Moreover, the relationship between the cryptographic kernel at the diffusion stage of ICMPD and modulo addition then XORing is explored thoroughly

Digital Image Encryption Technique using Block Based Scrambling and Substitution

A novel non-chaos based digital image encryption technique using a combination of diffusion and substitution process has been presented. A secret key of 128 bit sizes is used in the algorithm. In the diffusion (permutation) method, image is divided into different dynamic blocks which are key dependent. Further, each block is made to pass through eight rounds of permutation process. In this process, a zigzag mechanism is used to scramble the block pixels within the block. Then the resultant image i.e. the partially encrypted image is divided into various key based dynamic sub-images. Pixels of the sub-images are replaced with another pixel values within the block when each of the sub-images are passed through the substitution process. The substitution process comprises of four rounds. The proposed scheme is then compared with the standard AES algorithm. Investigation outcome shows that the proposed design methodology is efficient, fast and secur

Combining Several Substitution Cipher Algorithms using Circular Queue Data Structure

مع التوسع الثوري في الإنترنت ، تتزايد المعلومات العالمية في تطبيق تكنولوجيا الاتصالات، ويعزز النمو السريع لحجم البيانات الكبير الحاجة إلى تحقيق تقنيات آمنة وقوية وواثقة باستخدام خوارزميات فعالة مختلفة. تقدم هذه الورقة نظامًا تشفيريًا يجمع بين عدة خوارزميات لشفرة الاستبدال جنبًا إلى جنب مع هيكل بيانات طابور دائري . تقنيات الاستبدال المستخدمة هي: شفرة هوموفونك وشفرة بولي الفابيتك, قد دمجت في طابور دائري واحد مع أربعة مفاتيح مختلفة لكل منهما، والتي تنتج ثمانية مخرجات مختلفة لكل حرف وارد واحد. العمل الحالي ممكن تطبيقه بكفاءة لأمنية المعلومات الشخصية وأمنية اتصالات الشبكة كذلك.With the revolutionized expansion of the Internet, worldwide information increases the application of communication technology, and the rapid growth of significant data volume boosts the requirement to accomplish secure, robust, and confident techniques using various effective algorithms. Lots of algorithms and techniques are available for data security.  This paper presents a cryptosystem that combines several Substitution Cipher Algorithms along with the Circular queue data structure. The two different substitution techniques are; Homophonic Substitution Cipher and Polyalphabetic Substitution Cipher in which they merged in a single circular queue with four different keys for each of them, which produces eight different outputs for every single incoming letter. The present work can be applied efficiently for personal information security and network communication security as well, and the time required for ciphering and deciphering a message is less than 0.1 sec