COMPUTER SECURITY
(CS3801)
Lecture1.2 (Chapter 1)
Prepared by Dr. Lamiaa M. Elshenawy
1
CHAPTER1- OVERVIEW
OUTLINES
Computer Security Concepts
 The OSI Security Architecture
 Security Attacks
 Security Services
 Security Mechanisms

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CHAPTER1- OVERVIEW
SECURITY ATTACKS

1.
2.

1.
2.
3.
4.
Passive Attacks
Release of message contents
Traffic analysis
Active Attacks
Masquerade
Replay
Modification of messages
Denial of service
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CHAPTER1- OVERVIEW
PASSIVE ATTACKS
4
CHAPTER1- OVERVIEW
PASSIVE ATTACKS
5
CHAPTER1- OVERVIEW
ACTIVE ATTACKS
6
CHAPTER1- OVERVIEW
ACTIVE ATTACKS
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CHAPTER1- OVERVIEW
ACTIVE ATTACKS
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CHAPTER1- OVERVIEW
ACTIVE ATTACKS
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CHAPTER1- OVERVIEW
SECURITY SERVICES

RFC 2828 defines security service:
A processing or communication service that is provided by a
system to give a specific kind of protection to system resources;
security services implement security policies and are implemented
by security mechanisms.

X.800 divides these services into five
categories and fourteen specific services
X.800: ITU-T standard for security services
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CHAPTER1- OVERVIEW
SECURITY SERVICES
Authentication
1. Peer Entity Authentication
2. Data-Origin Authentication
 ACCESS CONTROL
Ability to limit and control the access to host
systems and applications via communications
links

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CHAPTER1- OVERVIEW
SECURITY SERVICES
Data Confidentiality
1. Connection Confidentiality
2. Connectionless Confidentiality
3. Selective-Field Confidentiality
4. Traffic-Flow Confidentiality

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CHAPTER1- OVERVIEW
SECURITY SERVICES
Data Integrity
1. Connection Integrity with Recovery
2. Connection Integrity without Recovery
3. Selective-Field Connection Integrity
4. Connectionless Integrity
5. Selective-Field Connectionless Integrity

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CHAPTER1- OVERVIEW
SECURITY SERVICES
Nonrepudiation
1. Nonrepudiation, Origin
2. Nonrepudiation, Destination

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CHAPTER1- OVERVIEW
SECURITY MECHANISMS
Encipherment
 Digital Signature
 Access Control
 Data Integrity
 Authentication Exchange
 Traffic Padding
 Notarization

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CHAPTER1- OVERVIEW
SECURITY MECHANISMS
Service
Enciph
erment
Digital
Signature
Peer Entity
Authentication
√
√
Data Origin
Authentication
√
√
Data
Integrity
Authentication
Exchange
Traffic
Padding
Notarization
√
√
Access Control
Confidentiality
√
Traffic Flow
Confidentiality
√
Data Integrity
√
Nonrepudiation
Access
Control
√
√
√
√
√
√
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