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Block cipher algorithms are a very important issue in the field of information security. Their simple structure and software-based encryption allow users to implement them in several applications such as: data security and cloud computing. In this paper, we reviewed 8 block ciphers that had been presented in the recently five years and were used in different applications. The 8 block ciphers are: DES, 3DES, Blowfish, Twofish, PRISENT, KLEIN, IDEA and AES. All of them are symmetric block ciphers with different designs. The comparative results showed that the block ciphers can still be used in different applications and fields. They showed that many modifications had been presented in which, chaotic maps had been implemented in key generation to enhance the robustness of the block ciphers and its randomness. The comparative results also showed that the AES is one of the block ciphers that is still unbroken algorithm and still modified to suit other new applications. Since less robust ciphers have continuous modification and enhancement in order to be more robust against some of probable attacks, the length of the key and its complexity and the structure of the ciphers are essential directions for improving block ciphers.

The world has witnessed steady changes and development at all levels, especially in the technological and innovation fields. Accordingly, the world has become a small village, thanks to the considerable advances of the means of communication, which transmit the information, with high accuracy and at record levels of speed. This prompted keeping pace with these media advances and its organization, in line with the new changes, in that it had (i.e. the advance of the means of communication) urged the carrying out of several daily transactions, through electronic media, with the spread of electronic commerce. These transactions did not see the light prior to the aforementioned advances. A matter that led many countries to intervene, with a view to regulating this new environment, on the one hand, and protecting the dealers with these media, on the other hand. And that through recognizing the authenticity (proof of evidence) of electronic signatures, exactly like their traditional handwritten counterparts, which is what countries throughout the world have consecrated and elevated to the status of being considered an approved proof of evidence. [ABSTRACT FROM AUTHOR]

Cryptocurrency, especially Bitcoin, is one of the most prominent developments in the field of currency trading at the present time. This research aims to define this currency, explain what it is, and how it is issued; it states the advantages and disadvantages that it is characterized with, and the benefits and harms resulting from its trading. Through the inductive approach, the research deals with the criteria and legitimate controls considered by the jurists regarding money, and the sayings of the current scholars searching in the legality of Bitcoin, the extent of monetary possession, and the consequences of the jurisprudential dispute on this issue. The research is divided into an introduction, a preface, three sections and a conclusion that included the most important findings of the research such as Bitcoin possesses several advantages that have given it great acceptance among a group of traders. Although it is characterized with these advantages, it does not have full monetary efficiency, the issuance of cryptocurrency is done by an identified financial authority, and providing security factors in its trading is relative. Thus, it will lead to provide the factor of confidence, and complete its general acceptance. The research recommends jurisprudence academies and researchers to conduct more studies on this subject in cooperation with scientific bodies specialized in digital systems and encryption programs in joint research projects to come up with more objective results. [ABSTRACT FROM AUTHOR]

The use of computers today is the most important and widespread means of storing, retrieving and circulating information through local and international networks and smart phones. Thus it is possible to intercept information through different networks or access to computers, whether independent or connected with the network for the purpose of viewing its contents or stealing information or to tamper with, and in this light must ensure the protection, reliability and credibility of information and preservation of the emergence of various means of protection such as the use of encryption and techniques of hiding or coverage of information. This research is based on a hybrid method between the Discrete Wavelets Translate technique (DWT) and the Chaos system based on the Least Significant Bit algorithm (LSB) to encrypt and hide a digital video file within another digital video that represents the cover by inserting the digital video file and segmenting it into a set of frames and then analyze each frame to its colors (red, green and blue) and then study the color values ​​of each frame and the process of encryption based on the equation of the logistics function (chaotic functions), and the application of the Discrete Wavelets Translate technique on the color slides of the cover frame. The hiding process is done using the Least Significant Bit algorithm based on the logistic function by calculating the series of random locations of cover area. The results showed that the hybridization of the Discrete Wavelets Translate technique and the chaos system based on the Least Significant Bit algorithm was an effective method for encrypting and hiding digital video files. After applying the work algorithms to a set of samples, the results showed consistency and compatibility in the encrypting and hiding process with the samples that was dealt with.