RAISE THE STRENGTH OF CRYPTOSYSTEM USING VARIETY EFFECTS

Nowadays, images became one of the most types of transmitted data through Internet. Some of these images carry secret information, therefore having an effective cryptosystem for hiding the information inside these images become an urgent need. Many traditional encryption methods are unable to achieve a high degree of protection for information. This paper presents nontraditional method for image encryption through applying substitution and transposition operations in different ways on both key and data. Series of (Linear and Circular), (Left, Right, Up and Down) rotation operations on (Bits and Bytes) of key and data are applied to make good confusion effects in the data. Moreover, XOR Boolean operations also applied on the key and data to make diffusion effects in the data. These two types of operations will produce a large set of keys. Using this large number of different keys in encrypting image will raise the strength of the encryption system used and achieve a high degree of protection for image. To test the security degree and performance of the encryption system, the system has been applied using different images and analyzing the results key space, key sensitivity, and statistical analysis and other criteria. From these tests, we can conclude that the encryption system can be used effectively to protect digital images

RAISE THE STRENGTH OF CRYPTOSYSTEM USING VARIETY EFFECTS

Nowadays, images became one of the most types of transmitted data through Internet. Some of these images carry secret information, therefore having an effective cryptosystem for hiding the information inside these images become an urgent need. Many traditional encryption methods are unable to achieve a high degree of protection for information. This paper presents nontraditional method for image encryption through applying substitution and transposition operations in different ways on both key and data. Series of (Linear and Circular), (Left, Right, Up and Down) rotation operations on (Bits and Bytes) of key and data are applied to make good confusion effects in the data. Moreover, XOR Boolean operations also applied on the key and data to make diffusion effects in the data. These two types of operations will produce a large set of keys. Using this large number of different keys in encrypting image will raise the strength of the encryption system used and achieve a high degree of protection for image. To test the security degree and performance of the encryption system, the system has been applied using different images and analyzing the results key space, key sensitivity, and statistical analysis and other criteria. From these tests, we can conclude that the encryption system can be used effectively to protect digital images

An encryption package for UNIX

Cryptography has a much wider application than secrecy, such as authentication and digital signature. There are two common types of cryptographic algoritlims - symmetric and asymmetric. The Data Encryption Standaid (DES) is the first and only, publicly available cryptographic algoritlim tliat has been widely used in commercial conmiunication. The DES is a block cipher symmetric algoritlim and its design is based on the Shannon\u27s two general principles - diffusion and confusion. With the decreased cost of hardware and a better understanding of block ciphers and cryptanalysis techniques, a number of DES-like ciphers have been proposed as the replacement for DES. One-way hashing functions are useful in implementing any digital signature schemes. A hashing function accepts a vai\u27iable size message M as input and outputs a fixed size representation of tlie message H(M). A number of hashing functions of fixed size or variable size message digest have been proposed. The cryptographic primitives (des, feal, loki, kliufu, and kliafre), block cipher based hashing algorithms (sbh and dbh), and key-less hashing algorithms (md4, md4x, md5 and haval) have been implemented as standard commands and C library calls for the UNIX Operating System

Likelihood Estimation for Block Cipher Keys

In this paper, we give a general framework for the analysis of block ciphers using the statistical technique of likelihood estimation. We show how various recent successful cryptanalyses of block ciphers can be regarded in this framework. By analysing the SAFER block cipher in this framework we expose a cryptographic weakness of that cipher

The design of a secure data communication system

The recent results of using a new type of chosen-plaintext attack, which is called differential cryptanalysis, makes most published conventional secret-key block cipher systems vulnerable. The need for a new conventional cipher which resists all known attacks was the main inspiration of this work. The design of a secret-key block cipher algorithm called DCU-Cipher, that resists all known cryptanalysis methods is proposed in this dissertation. The proposed method is workable for either 64-bit plaintext/64-bit ciphertext blocks, or 128-bit plaintext/128-bit ciphertext blocks. The secret key in both styles is 128-bit long. This method has only four rounds and the main transformation function in this cipher algorithm is based on four mixed operations. The proposed method is suitable for both hardware and software implementation. It is also suitable for cryptographic hash function implementations. Two techniques for file and/or data communication encryption are also proposed here. These modes are modified versions of the Cipher-Block Chaining mode, by which the threat of the known-plaintext differential cyptanalytical attack is averted. An intensive investigation of the best known Identity-based key exchange schemes is also presented. The idea behind using such protocols, is providing an authenticated secret-key by using the users identification tockens. These kind of protocols appeared recently and are not standardized as yet. None of these protocols have been compared with previous proposals. Therefore one can not realize the efficiency and the advantages of a new proposed protocol without comparing it with other existing schemes of the same type. The aim of this investigation is to clarify the advantages and the disadvantages of each of the best known schemes and compare these schemes from the complixity and the speed viewpoint

The Quasigroup Block Cipher and its Analysis

This thesis discusses the Quasigroup Block Cipher (QGBC) and its analysis. We first present the basic form of the QGBC and then follow with improvements in memory consumption and security. As a means of analyzing the system, we utilize tools such as the NIST Statistical Test Suite, auto and crosscorrelation, then linear and algebraic cryptanalysis. Finally, as we review the results of these analyses, we propose improvements and suggest an algorithm suitable for low-cost FPGA implementation

Cipher Text to Be Transmitted and Cryptanalysis in Network Security

Abstract-In this paper, we propose an encryption algorithm to encrypt plaintext to cipher text. We divide plaintext into numeric and non-numeric fields, also, we pack the numeric fields to produce packed numeric table and combine it with symbol fields to produce the new plaintext. We apply the basic computing operations, e.g., inserting dummy symbols, rotating, transposition, shifting and complement, in the proposed algorithm to encrypt plaintext to cipher text. The produced the cipher text which contains the plaintext, relative data and tables of encryption is transmitted to the receiver through the network. We also propose the cryptanalysis about these algorithms. It can be shown that the proposed algorithm is more secure in network security