Pure-JS RC4 stream cipher — KSA + PRGA implemented by hand. Output as hex or Base64. For learning and legacy compatibility only.
Pick Encrypt or Decrypt, choose output format (Hex or Base64), type your input and a key, then click Run. RC4 key scheduling (KSA) and the keystream generator (PRGA) are both implemented from scratch. Encryption is symmetric: encrypting the ciphertext back with the same key returns the original plaintext. Note: RC4 is broken and forbidden in modern protocols (TLS, WPA2) — this tool is for study and reading legacy data only.