Overview over protocols:

Authenticated Encryption (AE)

This combines the logic of Message Authentication Codes (MAC), which provides integrity and the Symmetric Encryption (AE), which provides Confidentiality.

There are three generic composition methods to ensure integrity and confidentiality in messages:

Encrypt-then-MAC (EtM)

Encrypt-and-MAC (E&M)

MAC-then-Encrypt (MtE)

Authenticated Encryption with Associated Data (AEAD)

Is a variant of AE in which some data is left unencrypted, but we can still provide integrity on the data.

AES Galois Counter Mode (GCM)

Is an example of an AEAD.

It uses CTR (Counter Mode, which is a block cipher) and additionally uses MAC, which in our case is a GMAC (Galois MAC).