Suppose we have a block cipher with block size and 3-bit keys .  Encryption is as follows:

where is binary bitwise addition.  (So , where , .  For example, . )

Alice wishes to send a message to Bob with data origin authentication, where 

Suppose Alice and Bob agreed to use the above block cipher to compute CBC-MACs without the optional processing and truncating, and suppose they agree on the key .

What is the message authentication code MAC on Alice's message?