Security models

Question 1

How can the security of a distributed system be achieved?

Answer 1

Securing the processes and channels used for their interactions and protecting the objects that they encapsulate against unauthorised access

Question 2

Describe how objects are protected

Answer 2

The server is responsible for enforcing access rights associated with each object and verifying the identity of the principal behind each request
The client may check the identity of the principal behind the server (server authentication)

Question 3

Describe how processes and communication is secured

Answer 3

Making sure the processes are free of bugs and malicious code
Making sure the processes are protected from direct interference from other processes on that machine

Question 4

How can security threats be modelled?

Answer 4

Postulate an enemy that is capable of sending any messages to any process, reading or copying any message sent between a pair of processes, perhaps also modifying or replacing any message