Problem 2 Your colleague knew that EncryptandMac does not always yield a secure authen+ ticated encryption scheme, even if the base encryption and MAC schemes are so cure. For example, if a deterministic MAC is used, then two encryptions of equal messages will have equal parts. Therefore, he proposed to encrypt and MAC the message concatenated with a random string. Namely, a ciphertext is computed as 5a.. [M||R)]|Tgm (MHR) for random R (picked at random for each message). We as sume that the message spaces for encryption and MAC can easily accommodate extra strings. Verication is dened accordingly. Convince your manager that your col~ league's generic composition proposal is not good securitymwise. Your argument does not have to be formal1 but it has to he convincing