Public-Key Cryptography and Message Authentication

 3.1 List three approaches to message authentication.

3.2 What is a message authentication code?

3.3 What properties must a hash function have to be useful for message authentication?

3.4 In the context of a hash function, what is a compression function?

3.5 What are the principal ingredients of a public-key cryptosystem?

3.6 List and briefly define three uses of a public-key cryptosystem.

3.7 What is the difference between a private key and a secret key?

3.8 What is a digital signature?

 Answer the above questions and please find the attached reference file for the answers.