The Helion ARC4 core implements the Alleged RC4 stream cipher algorithm. The RC4 algorithm itself was developed by Ron Rivest in 1987 and was originally a trade secret of RSA Security. However, a description of the algorithm became widely available on the Internet in 1994 and so the algorithm is no longer considered a trade secret, although the name RC4 itself is still trademarked. Legal third party implementations are therefore often referred to as Alleged RC4, which is usually abbreviated to ARC4.
The Helion ARC4 core generates a byte-wide keystream which is used to perform encryption and decryption when XOR’ed with either plaintext or ciphertext. It supports variable length key sizes of up to 16 bytes long. Applications include hardware implementations of the WEP and WPA 802.11i wireless security protocols, as well as TLS/SSL (Transport Layer Security, formerly Secure Sockets Layer) applications.