Cryptanalysis of the RC4 Stream Cipher using Evolutionary ...

As has become apparent, the RC4 stream cipher is very well designed to combat cryptanalysis.
Conversely, its security appears to rely on the lack of computer power of modern
computers to remain secure.
3.2 Review of Evolutionary Algorithms Literature
Since evolutionary algorithms help to reduce a search space through the use of fitness
functions and methods relating to areas such as physics and biology, they have long been
explored as a viable alternative to brute-force methods for finding a cryptographic system
key. Many of these keys have vast search spaces that these cryptosystems rely on to make
key derivation impractical with modern computing power and the computing power of
future generations. Any methods that can help direct a search for a key over an extremely
vast search space is one worth investigating. In Section 3.2.1 various cryptanalysis methods
pertaining to GAs will be examined. This will be followed by a review of cryptanalysis
methods that utilize PSOs in Section 3.2.2.
3.2.1 Cryptanalysis Using Genetic Algorithms
One of the first uses of soft computing to aid in the cryptanalysis of a cipher was in 1993 by
Richard Spillman. He chose to attack the Knapsack cipher using a genetic algorithm. His
research utilized a GA to decrypt cipher text letter by letter with an average decryption
time of 84 seconds making the attack a practical use of soft computing methods [36]. Yaseen
and Sahasrabuddhe used a genetic algorithm to attack the Chor-Rivest Knapsack public key
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