W4

 In 2-3 lines with references. Please complete below 

Do the following review questions:

• 4.1 List ways in which secret keys can be distributed to two communicating parties.
• 4.2 What is the difference between a session key and a master key?
• 4.3 What is a key distribution center?
• 4.4 What entities constitute a full-service Kerberos environment?
• 4.5 In the context of Kerberos, what is a realm?
• 4.6 What are the principal differences between version 4 and version 5 of Kerberos?
• 4.7 What is a nonce?
• 4.8 What are two different uses of public-key cryptography related to key distribution?
• 4.9 What are the essential ingredients of a public-key directory?
• 4.10 What is a public-key certificate?
• 4.11 What are the requirements for the use of a public-key certificate scheme?
• 4.12 What is the purpose of the X.509 standard?
• 4.13 What is a chain of certificates?
• 4.14 How is an X.509 certificate revoked?