Encrypt given data using camellia-256-ofb cipher algo. Camellia in 256-bit key size with OFB mode, converting a block cipher into a stream cipher using a feedback loop. OFB mode is part of Camellia's broad suite of secure modes developed by Mitsubishi Electric and NTT. OFB is secure but may still be susceptible to key reuse and error propagation issues. Our encryption process prepends the IV string used during the encryption process in the encrypted data so that it can be used during decryption.