Recall that a MAC is given by the CBC residue, that is, the last ciphertext block when the data is encrypted in CBC mode. Given data X, key K, and an IV, define F(X) to be the MAC of X. a. Is F...

Recall that a MAC is given by the CBC residue, that is, the last ciphertext block when the data is encrypted in CBC mode. Given data X, key K, and an IV, define F(X) to be the MAC of X.

a. Is F one-way, that is, given F(X) is it possible to determine ΧΊ

b. Is F collision resistant, that is, given F(X) is it possible to find a value Y such that F(Y) = F(X)7