This chapter includes contents: To discuss security threats and attacks; to explain the fundamentals of encryption, authentication, and hashing; to examine the uses of cryptography in computing; to describe the various countermeasures to security attacks. | Chapter 15: Security Operating System Concepts – 9th Edition Silberschatz, Galvin and Gagne ©2013 Chapter 15: Security The Security Problem Program Threats System and Network Threats Cryptography as a Security Tool User Authentication Implementing Security Defenses Firewalling to Protect Systems and Networks Computer-Security Classifications An Example: Windows 7 Operating System Concepts – 9th Edition Silberschatz, Galvin and Gagne ©2013 Objectives To discuss security threats and attacks To explain the fundamentals of encryption, authentication, and hashing To examine the uses of cryptography in computing To describe the various countermeasures to security attacks Operating System Concepts – 9th Edition Silberschatz, Galvin and Gagne ©2013 The Security Problem System secure if resources used and accessed as intended under all circumstances Unachievable Intruders (crackers) attempt to breach security Threat is potential security violation Attack is attempt to breach security Attack can be accidental or malicious Easier to protect against accidental than malicious misuse Operating System Concepts – 9th Edition Silberschatz, Galvin and Gagne ©2013 Security Violation Categories Breach of confidentiality Unauthorized reading of data Breach of integrity Unauthorized modification of data Breach of availability Unauthorized destruction of data Theft of service Unauthorized use of resources Denial of service (DOS) Prevention of legitimate use Operating System Concepts – 9th Edition Silberschatz, Galvin and Gagne .