I was reading about Encrypt-then-MAC and everywhere I go it seems people include the IV with the ciphertext generated for each message then MAC that and send all the information concatenated. Why do ...
A fixed length CBC-MAC uses an all-zero block as the initialization vector. Suppose that we used a randomized IV instead, and sent the IV along with the tag. So if the message $m$ will be $m = b_1 || ...