### A Robust Approach for Mixed Technique of Data Encryption Between DES and RC4 Algorithm

#### Abstract

In this research, the well-known encryption algorithms in the encryption Systems, namely DES & RC4 and the advantages and disadvantages of each algorithm are reviewed and evaluated. These two algorithms are combined to produce of new algorithm which is more efficient unscrambling due to the increasing of the level of complexity that make it highly resistance to several attacks. The new algorithm is implemented to show its efficiency in term of time complexity, (i.e. Breaking the code will be much more complicated than if it would have been occurring through the use of each algorithm individually), this process can be achieved with a very small time difference (approximately neglected in the encryption process(. When this algorithm is applied and tested in practice the following result has been obtained:When a block is encrypted using the DES algorithm, the time spent may be (0.000034) milliseconds, but when using the new algorithm to encrypt the same block, the time taken will be about (0.000042) milliseconds. To encrypt 1024 blocks using the DES algorithm, it will take a time of (0.0406),while by using the new algorithm the time taken for encryption is only (0.051). This gives very little increase in time compared to increasing of complexity obtained. Since the new algorithm combining from the two previous, ones allows us to encrypt each block with a key differs from the other one (i.e. each block is encrypted with a different key depending on the preceding block), making it very difficult to break the code leading to an increase in security and information protection against decoding.

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