XORByte-wise XOR with cycling key, output as hex or Base64.XOR is symmetric and offers no authentication—do not use for real secrecy; fine for CTFs, demos, or light obfuscation.EncryptPlaintext (UTF-8)helloKey (UTF-8, repeated)Output formatHexBase64XOR → ciphertextCiphertextDecryptCiphertext (Hex)XOR → plaintextPlaintext