youssef ismael – iraqi great artist – is one of the nobles in playwriting either in writing or in criticism. al – aani has enjoyed beresht’s theories and ideas while his idea were based on political requirements which was dominant in that era; he wanted to choose a frame for playwriting which considered all types of people of the society. the present article which is analytical – descriptive, s...

One of the major cipher symmetric algorithms is AES. Its main feature is to use S-BOX step, which is the only non-linear part of this standard possessing fixed structure. During the previous studies, it was shown that AES standard security was increased by changing the design concepts of S-BOX and production of dynamic S-BOX. In this paper, a change of AES standard security is studied by produc...

In cryptography, a Substitution box (S-box) is one of the basic components of a symmetric key cryptography. Generally, it transforms a number of m input bits into n output bits. In this paper, there are presented the cryptographic properties of S-boxes and it is introduced a knowledge-based schema for building S-boxes.

Random bijective S-box generation methods are considered. An alternative S-box generation method by forming compositions of permutations from some fixed set is proposed. Experiments show that the rate of acceptable S-boxes for all the methods considered is essentially the same. The advantage of the composition method is an obvious parametrization, with the potentially large key space.

In modern cryptography, the P-Boxes and S-boxes are used to make the relation between the plaintext and the cipher text difficult to realize. P-Box is a tool that changes the order of the input bits and they appear in the output. In this case, the key is order transmission of input bits in output bits.An S-box is a basic component which performs substitution. In this paper, a new method for the...

In this note we analyse Noekeon, a 128-bit block cipher submitted to the NESSIE project. It is shown that for six of seven S-boxes which satisfy the design criteria of the Noekeon designers the resulting block ciphers are vulnerable to either a differential attack, a linear attack or both. One conclusion is that Noekeon is not designed according to the wide trail strategy. Also, it is shown tha...

This paper presents modifications of the Diffie-Hellman (DH) key exchange method. The presented modifications provide better security than other key exchange methods. We are going to present a dynamic security that simultaneously realizes all the three functions with a high efficiency and then give a security analysis. It also presents secure and dynamic key exchange method. Signature, encrypti...