AANSWERSNSWERS TOTO Q QUESTIONSUESTIONS1.1 The OSI Security Architecture is a framework that provides a systematic way of defining the requirements for security and characterizing the approaches to satisfying those requirements。 The document defines security attacks, mechanisms， and services, and the relationships among these categories。1。2 Passive attacks have to do with eavesdropping on， or monitoring, transmissions. Electronic mail, file transfers， and client/server exchanges are examples of transmissions that can be monitored。 Active attacks include the modification of transmitted data and attempts to gain unauthorized access to computer systems。1.3Passive attacks： release of message contents and traffic analysis. Active attacks： masquerade, replay， modification of messages， and denial of service。1。4Authentication: The assurance that the communicating entity is the one that it claims to be。 Access control： The prevention of unauthorized use of a resource （i.e。, this service controls who can have access to a resource, under what conditions access can occur, and what those accessing the resource are allowed to do）。 Data confidentiality： The protection of data from unauthorized disclosure。 Data integrity： The assurance that data received are exactly as sent by an authorized entity (i.e., contain no modification， insertion， deletion, or replay）。 Nonrepudiation： Provides protection against denial by one of the entities involved in a communication of having participated in all or part of the communication。 Chapter 1：Introduction..................................................................................................5Chapter 2：Classical Encryption Techniques............................................................
