Encrypt given data using des-ofb cipher algo. DES in OFB (Output Feedback) mode, turning the block cipher into a stream cipher using a feedback mechanism. OFB mode was used to improve the flexibility of DES by enabling it to encrypt smaller blocks of data while minimizing error propagation. DES in OFB is still insecure due to the inherent weaknesses of the DES algorithm, especially the 56-bit key length. Our encryption process prepends the IV string used during the encryption process in the encrypted data so that it can be used during decryption.