The Rivest Cipher 4 (RC4) encryption algorithm is a symmetric encryption method in which the key is generated by a random number generator. RC4 works with a secret key that is known to the sender and the receiver and whose algorithm is used for both encryption and decryption. The variable key length can be up to 2,048 bits long. Each character is encrypted individually. RC4 is considered very secure, although it is relatively simple.
This method, named after its developer Ronald L. Rivest, is a stream cipher and is suitable for encrypting continuous data streams and is much faster than RSA encryption.