The RC4 encryption algorithm

The RC4 encryption algorithm was developed by Ronald Rivest of RSA. This is a shared key stream cipher algorithm which requires a secure exchange of a shared key which is outside the specification of the RC4 algorithm. The RC4 algorithm is used identically for encryption and decryption as the data stream is simply XORed with the generated key sequence. The algorithm is serial as it requires successive exchanges of state entries based on the key sequence. Hence implementations can be very computationally intensive. This algorithm has been released to the public and is implemented by many programmers. This encryption algorithm is used by standards such as IEEE 802.11 within WEP (Wireless Encryption Protocol) using a 40 and 128-bit keys. Published procedures exist for cracking the security measures as implemented in WEP.