Analysis Methods for (Alleged) RC4

The security of the alleged RC4 stream cipher and some variants is investigated. Cryptanalytic algorithms are developed for a known plaintext attack where only a small segment of plaintext is assumed to be known. The analysis methods reveal intrinsic properties of alleged RC4 which are independent of the key scheduling and the key size. The complexity of one of the attacks is estimated to be less than the time of searching through the square root of all possible initial states. However, this still poses no threat to alleged RC4 in practical applications.