We consider two possible notions of authenticity for symmetric encryption schemes, namely integrity of plaintexts and integrity
of ciphertexts, and relate them to the standard notions of privacy for symmetric encryption schemes by presenting implications
and separations between all notions considered. We then analyze the security of authenticated encryption schemes designed
by “generic composition,” meaning making black-box use of a given symmetric encryption scheme and a given MAC. Three composition
methods are considered, namely Encrypt-and-MAC plaintext, MAC-then-encrypt, and Encrypt-then- MAC. For each of these, and
for each notion of security, we indicate whether or not the resulting scheme meets the notion in question assuming the given
symmetric encryption scheme is secure against chosen-plaintext attack and the given MAC is unforgeable under chosen-message
attack. We provide proofs for the cases where the answer is “yes” and counter-examples for the cases where the answer is “no.”