(RC4 Encryption-Algorithm) – also known as “Rivest Cipher 4” is a form of stream cipher. It encrypts messages one byte at a time via an algorithm. Plenty of stream ciphers exist, but RC4 is among the most popular. It’s simple to apply, and it works quickly, even on very large pieces of data.
Here is an example of RC4 BASE64 encryptor script that uses Base64 encoding and RC4 encryption-algorithm. It uses symmetric passwords, so it is not suitable for encrypting web data from browser to server, but can be used from server to browser. It could be cracked using brute force, but accepts very long passwords (up-to 256 characters), making that difficult or time consuming to do. As an added benefit, it makes the output completely incomprehensible with even small variations in decryption keys.