Encrypt given data using seed-cfb cipher algo. SEED in CFB (Cipher Feedback) mode, converting the block cipher into a stream cipher. CFB mode was introduced for SEED to handle streams of data more effectively while maintaining the security of the algorithm. SEED-CFB is secure but slower than modern alternatives like AES. Our encryption process prepends the IV string used during the encryption process in the encrypted data so that it can be used during decryption.