This library implements the Alleged RC4 cipher, which is described for
example in Applied Cryptography. It is believed to be compatible
with RC4[TM], a proprietary cipher of RSA Security Inc.
RC4 is a stream cipher with variable key length. Typically, 128 bit
(16 byte) keys are used for strong encryption, but shorter insecure
key sizes have been widely used due to export restrictions.
RC4 consists of a key setup phase and the actual encryption or
RC4_set_key() sets up the RC4_KEY key using the len bytes long
key at data.
RC4() encrypts or decrypts the len bytes of data at indata using
key and places the result at outdata. Repeated RC4() calls with
the same key yield a continuous key stream.
Since RC4 is a stream cipher (the input is XORed with a pseudo-random
key stream to produce the output), decryption uses the same function
calls as encryption.
Applications should use the higher level functions
etc. instead of calling the RC4 functions directly.