Say CBC- mode is used with a block cipher having a 256-bit key and 128-bit block length to encrypt a 1024-bit message. What is the length of the resulting ciphertext? (Assume a padding scheme that appends to the message a 1 and as many Os as needed.) Say CBC- mode is used with a block cipher having a 256-bit key and 128-bit block length to encrypt a 1024-bit message. What is the length of the resulting ciphertext? (Assume a padding scheme that appends to the message a 1 and as many Os as needed.)