a) Describe the function of Public Key Encryption and Symmetric Encryption. In your answer, you should explain why SSL/TLS uses a combination of public key encryption and symmetric encryption.

b) Describe what is meant by a digital signature and its role in a digital certificate, explaining also the function of the digital certificate.

c) What is the purpose of the message digest or hash function used in digital signatures, and what risks might be associated with Hash Collisions?