Alice uses the OFB mode to encrypt her emails sent to Bob, but instead of using randomly generated IVs, she always uses the same IV to encrypt her emails. Charlie somehow gets the following data:
- The first 8 bits of the first ciphertext block: 0x11010101
- The first 8 bits of the first plaintext block: 0x01111001
- The first 8 bits of the second ciphertext block: 0x10100100
- The first 8 bits of the second plaintext block: 0x11001010
Charlie also get a copy of Alice’s newly encrypted message, the first 8 bits of the first two blocks are 0x01010010 and 0x01101001, respectively.
Please derive the first 8 bits of the first two blocks of the plaintext.