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The data encryption standard (DES) is one of the most common symmetric encryption algorithms, but it experiences many problems. For example, it uses only one function (XOR) in the encryption process, and the combination of data is finite because it occurs only twice and operates on bits. This paper presents a new modification of the DES to overcome these problems. This could be done through adding a new level of security by increasing the key space (using three keys) during the 16 rounds of the standard encryption algorithm and by replacing the predefined XOR operation with a new # operation. Our proposed algorithm uses three keys instead of one. The first key is the input key used for encrypting and decrypting operations. The second key is used for determining the number of bits, while the third key is used for determining the table numbers, which are from 0 to 255. Having evaluated the complexity of our proposed algorithm, the results show that it is the most complex compared with the well-known DES and other modified algorithms. Consequently, in our proposed algorithm, the attacker try a number of attempts 21173 at minimum to decrypt the message. This means that the proposed DES algorithm will increase the security level of the well-known DES.

Blowfish is a block cypher algorithm used in many applications to enhance security, but it includes several drawbacks. For example, the mix between the key and data is limited. This paper presents a new modification to the Blowfish algorithm to overcome such problems realised through a multi-state operation instead of an XOR. Our proposed algorithm uses three keys in the encryption and decryption processes instead of one for controlling the variable block bits sizes (1, 2, 4, and 8) bits and for determining the state table numbers. These tables are formed from the addition in a Galois field GF (2 n ) based on block bit size to increase the complexity of the proposed algorithm. Results are evaluated based on the criteria of complexity, time encryption, throughout, and histogram, and show that the original Blowfish, those modified by other scholars, and our proposed algorithm are similar in time computation. Our algorithm is demonstrated to be the most complex compared with other well-known and modified algorithms. This increased complexity score for our proposed Blowfish makes it more resistant against attempts to break the keys.

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This paper introduces an improved advanced encryption standard (AES) cipher algorithm by proposing a new algorithm based on magic square to decrease the AES execution time. This is done by replacing Mixcolumn function with magic square of order 6. This paper raises the security level of AES cryptosystem by using another key, which is generated using magic square while decreasing the execution time. For application of encrypting a colouring image, visual studio and MATLAB programs have been used as means for computing results. The results of complexity, time execution, National Institute of Standards and Technology (NIST) tests, histogram, differential attacks and peak signal to noise ratio (PSNR) are computed and compared with the original AES cryptosystem, the original and the proposed algorithms. The proposed algorithm results in reasonable findings under several evaluation metrics. For instance, the complexity of our proposed algorithm is higher than the basic AES while decreases the time execution. The experimental results show that the suggested algorithm provides an efficient and secure way for image encryption. The suggested algorithm leads to leverage the complexity of cipher process as well as to make the linear and differential cryptanalysis harder by pre-process the input image initial step of the proposed AES.