A basic RC4 encryption and decryption implementation in C#
RC4 is a symmetric key cryptographic algorithm that was widely used in the past for secure communication. It is a stream cipher, which means that it encrypts data one bit or byte at a time. The algorithm uses a variable-length key to initialize a pseudorandom number generator, which is then used to generate a stream of pseudorandom numbers. These numbers are then combined with the plaintext to produce the ciphertext. Because the key is used to initialize the pseudorandom number generator, the same key must be used for both encryption and decryption.
RC4 was widely used in the past for secure communication, particularly in protocols such as Secure Sockets Layer (SSL) and Wi-Fi Protected Access (WPA). However, it has since been replaced by more secure algorithms in most cases due to vulnerabilities that have been discovered in the algorithm. It is not recommended to use RC4 in any new systems, and it should only be used in legacy systems where it is necessary for compatibility reasons.