I have been trying to get my head around the MAC part of the TLS connection as both the key exchange and cipher seem to make sense.
As far as I understand the MAC is used to ensure that the information that is received is authentic, but here are my questions:
Is a MAC sent only during the handshake (the async bit) or is one sent with each piece of transferred information (both the async and sync bits)?
When a client talks to a server, does it always send a MAC?
When a server talks to a client, does it always a send a MAC?
In regards to TLS, is a MAC created via EtM, E&M or MtE? In short, is the MAC sent as plaintext?
If a MAC doesn't match-up is the connection terminated? Does the whole handshake process have to begin again?