Chapter 8 - Security and protection. Security and protection measures together ensure that only authorized users can access a file. This chapter discusses different kinds of security and protection threats in an operating system, measures used to thwart these threats, and the role played by the encryption technique in implementing these measures. | PROPRIETARY MATERIAL. © 2007 The McGraw-Hill Companies, Inc. All rights reserved. No part of this PowerPoint slide may be displayed, reproduced or distributed in any form or by any means, without the prior written permission of the publisher, or used beyond the limited distribution to teachers and educators permitted by McGraw-Hill for their individual course preparation. If you are a student using this PowerPoint slide, you are using it without permission. Security and Protection Security Guarding users’ data and programs against interference by external entities such as non-users or programs outside an OS Key technique: Authentication of users Protection Guarding users’ data and programs against interference by internal entities such as users of the system and their programs Key technique: Authorization of users Terminology used in security and protection Authentication Verifying the identity of a user Operating systems tend to perform authentication by knowledge A person is the . | PROPRIETARY MATERIAL. © 2007 The McGraw-Hill Companies, Inc. All rights reserved. No part of this PowerPoint slide may be displayed, reproduced or distributed in any form or by any means, without the prior written permission of the publisher, or used beyond the limited distribution to teachers and educators permitted by McGraw-Hill for their individual course preparation. If you are a student using this PowerPoint slide, you are using it without permission. Security and Protection Security Guarding users’ data and programs against interference by external entities such as non-users or programs outside an OS Key technique: Authentication of users Protection Guarding users’ data and programs against interference by internal entities such as users of the system and their programs Key technique: Authorization of users Terminology used in security and protection Authentication Verifying the identity of a user Operating systems tend to perform authentication by knowledge A person is the user she claims to be if she can exhibit some requisite knowledge, such as a password Authorization Verifying a user’s right to access a resource in a specific manner Generic security and protection set-ups in an OS The authentication service generates an authentication token It is passed to the service & resource manager with each request Authorization service uses it to check whether user has access privileges Policies and mechanisms of security and protection Security Policy Whether a person can become a user of a system (implemented by system administrator) Mechanism Add or delete users, perform authentication, encrypt data Protection Policy Which user can access a file in what manner (set by a file owner) Mechanism Set or change authorization information, check whether a request conforms to a user’s privileges Goals of security and protection Computer security and protection has four goals Secrecy (also called confidentiality) Only authorized users should be able to access .
