What is RC4 Encryption?
RC4 was developed by Ron Rivest in 1987. It is a variable-key-size stream cipher. The details of the algorithm have not been officially published. However, the algorithm’s internals have been posted on the Internet, and the book Applied Cryptography contains its detailed description. The algorithm is extremely easy to describe and program.
Just like RC2, 40-bit RC4 is supported by the Microsoft Base Cryptographic provider, and the Enhanced provider allows keys in the range of 40 to 128 bits in 8-bit increments.