On a network, an attacker intercepts a message consisting of a header and a body. Describe (using one sentence each) what the attacker does to the message header and/or body, if the attacker performs a 1) replay attack 2) masquerade attack 3) modification attack with or on the message, separately.

Describe, in one sentence, what the sender of the message does to protect the message against the masquerade and modification attacks together using a single method.