Encrypt given data using rc2-ofb cipher algo. RC2 in OFB (Output Feedback) mode, turning the block cipher into a stream cipher with feedback. OFB mode was introduced to RC2 to handle streams of data more efficiently, though it does not eliminate RC2's inherent weaknesses. RC2-OFB is considered insecure and not recommended for modern applications. Our encryption process prepends the IV string used during the encryption process in the encrypted data so that it can be used during decryption.