RC4  Software
RC4 is a stream cipher designed by Rivest for RSA Data Security (now RSA
Security). It is a variable keysize stream cipher with byteoriented operations. The algorithm is based on the use of a random permutation. Analysis shows that the period of time to crack the cipher is overwhelmingly likely to be greater than 10^{100} seconds. Eight to sixteen machine operations are required per output byte, and the cipher can be expected to run very quickly in software. Independent analysts have scrutinized the algorithm and it is considered secure.
