RC4
RC4 stream cipher - encrypt and decrypt with a key. Legacy/educational use only.
Example
Plaintext: "Hello, World!" · Key: "mysecretkey"
How it works
RC4 (Rivest Cipher 4) is a stream cipher that generates a pseudorandom keystream using the Key-Scheduling Algorithm (KSA) and Pseudo-Random Generation Algorithm (PRGA). The keystream is XORed with the plaintext to produce ciphertext.
RC4 uses a 256-byte state array initialized with the key, then generates one byte of keystream per input byte. Because RC4 is symmetric, the same operation encrypts and decrypts.
Output is encoded as Base64 for transport. Reference: RFC 7465 (prohibition on RC4 in TLS)