In Sect. 10.1.3 we state that sender (or message) authentication always implies data integrity. Why? Is the opposite true too, i.e., does data integrity imply sender authentication? Justify both answers.

In this exercise, we want to consider some basic aspects of security services.

1. Does privacy always guarantee integrity? Justify your answer.

2. In which order should confidentiality and integrity be assured (should the entire message be encrypted first or last)? Give the rationale for your answer.