Transcript L1 Introduction to Data Security and Encryption.ppt

Data Security and Encryption
(CSE348)
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Dr. Basit Raza
Assistant Professor
Comsats Institute of Information
Technology, Islamabad
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Course Outline
In this course we will follow the mentioned book
Cryptography and Network Security”,
5th Edition by William Stallings.
The book is organized into seven parts:
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Course Outline
Part One: Symmetric Ciphers:
Provides a survey of symmetric encryption,
including classical and modern algorithms. The
emphasis is on the two most important algorithms,
the Data Encryption Standard (DES) and the
Advanced Encryption Standard (AES).This part
also covers the most important stream encryption
algorithm,RC4,and the important topic of
pseudorandom number generation.
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Course Outline
Part Two: Asymmetric Ciphers:
Provides a survey of public-key algorithms,
including RSA (Rivest-Shamir-Adelman) and
elliptic curve.
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Course Outline
Part Three: Cryptographic Data Integrity
Algorithms:
Begins with a survey of cryptographic
hash functions. This part then covers two
approaches to data integrity that rely on
cryptographic hash functions: message
authentication codes and digital signatures.
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Course Outline
Part Four: Mutual Trust:
Covers key management and key distribution
topics and then covers user authentication
techniques.
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Course Outline
Part Five: Network Security and Internet
Security:
Examines the use of cryptographic
algorithms and security protocols to provide
security over networks and the Internet. Topics
covered include transport-level security, wireless
network security, e-mail security, and IP security.
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Course Outline
Part Six: System Security:
Deals with security facilities designed to protect a
computer system from security threats, including
intruders, viruses, and worms. This part also looks
at firewall technology.
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Course Outline
Part Seven: Legal and Ethical Issues:
Deals with the legal and ethical issues related
to computer and network security.
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Course Outline
Chapter 1 Overview
1.1 Computer Security Concepts
1.2 The OSI Security Architecture
1.3 Security Attacks
1.4 Security Services
1.5 Security Mechanisms
1.6 A Model for Network Security
1.7 Recommended Reading and Web Sites
1.8 Key Terms and Review Questions
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Course Outline
PART ONE SYMMETRIC CIPHERS
Chapter 2 Classical Encryption Techniques
2.1 Symmetric Cipher Model
2.2 Substitution Techniques
2.3 Transposition Techniques
2.4 Rotor Machines
2.5 Steganography
2.6 Recommended Reading and Web Sites
2.7 Key Terms and Review Questions
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Course Outline
Chapter 3 Block Ciphers and the Data Encryption
Standard
3.1 Block Cipher Principles
3.2 The Data Encryption Standard (DES)
3.3 A DES Example
3.4 The Strength of DES
3.5 Differential and Linear Cryptanalysis
3.6 Block Cipher Design Principles
3.7 Recommended Reading and Web Site
3.8 Key Terms and Review Questions
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Course Outline
Chapter 4 Basic Concepts in Number Theory and
Finite Fields
4.1 Divisibility and the Division Algorithm
4.2 The Euclidean Algorithm
4.3 Modular Arithmetic
4.4 Groups, Rings, and Fields
4.5 Finite Fields of the Form GF(p)
4.6 Polynomial Arithmetic
4.7 Finite Fields of the Form GF(2n)
4.8 Recommended Reading and Web Sites
4.9 Key Terms and Review Questions
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Course Outline
Chapter 5 Advanced Encryption Standard
5.1 The Origins AES
5.2 AES Structure
5.3 AES Round Functions
5.4 AES Key Expansion
5.5 An AES Example
5.6 AES Implementation
5.7 Recommended Reading and Web Sites
5.8 Key Terms and Review Questions
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Course Outline
Chapter 6 Block Cipher Operation
6.1 Multiple Encryption and Triple DES
6.2 Electronic Codebook Mode
6.3 Cipher Block Chaining Mode
6.4 Cipher Feedback Mode
6.5 Output Feedback Mode
6.6 Counter Mode
6.7 XTS Mode for Block-Oriented Storage Devices
6.8 Recommended Web Site
6.9 Key Terms and Review Questions
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Course Outline
Chapter 7 Pseudorandom Number Generation and
Stream Ciphers
7.1 Principles of Pseudorandom Number Generation
7.2 Pseudorandom Number Generators
7.3 Pseudorandom Number Generation Using a Block
Cipher
7.4 Stream Ciphers
7.5 RC4
7.6 True Random Numbers
7.7 Recommended Reading
7.8 Key Terms and Review Questions
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Course Outline
PART TWO ASYMMETRIC CIPHERS
Chapter 8 More Number Theory
8.1 Prime Numbers
8.2 Fermat’s and Euler’s Theorems
8.3 Testing for Primality
8.4 The Chinese Remainder Theorem
8.5 Discrete Logarithms
8.6 Recommended Reading and Web Sites
8.7 Key Terms and Review Questions
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Course Outline
Chapter 9 Public-Key Cryptography and RSA
9.1 Principles of Public-Key Cryptosystems
9.2 The RSA Algorithm
9.3 Recommended Reading and Web Sites
9.4 Key Terms and Review Questions
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Course Outline
Chapter 10 Other Public-Key Cryptosystems
10.1 Diffie-Hellman Key Exchange
10.2 ElGamal Cryptosystem
10.3 Elliptic Curve Arithmetic
10.4 Elliptic Curve Cryptography
10.5 Pseudorandom Number Generation Based on an
Asymmetric Cipher
10.6 Recommended Reading and Web Sites
10.7 Key Terms and Review Questions
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Course Outline
PART THREE CRYPTOGRAPHIC DATA
INTEGRITY ALGORITHMS
Chapter 11 Cryptographic Hash Functions
11.1 Applications of Cryptographic Hash Functions
11.2 Two Simple Hash Functions
11.3 Requirements and Security
11.4 Hash Functions Based on Cipher Block Chaining
11.5 Secure Hash Algorithm (SHA)
11.6 SHA-3
11.7 Recommended Reading and Web Sites
11.8 Key Terms and Review Questions
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Course Outline
Chapter 12 Message Authentication Codes
12.1 Message Authentication Requirements
12.2 Message Authentication Functions
12.3 Message Authentication Codes
12.4 Security of MACs
12.5 MACs Based on Hash Functions:HMAC
12.6 MACs Based on Block Ciphers: DAA and CMAC
12.7 Authenticated Encryption: CCM and GCM
12.8 Pseudorandom Number Generation Using Hash
Functions and MACs
12.9 Recommended Reading
12.10 Key Terms and Review Questions
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Course Outline
Chapter 13 Digital Signatures
13.1 Digital Signatures
13.2 ElGamal Digital Signature Scheme
13.3 Schnorr Digital Signature Scheme
13.4 Digital Signature Standard (DSS)
13.5 Recommended Reading and Web Sites
13.6 Key Terms and Review Questions
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Course Outline
PART FOUR MUTUAL TRUST
Chapter 14 Key Management and Distribution
14.1 Symmetric Key Distribution Using Symmetric
Encryption
14.2 Symmetric Key Distribution Using Asymmetric
Encryption
14.3 Distribution of Public Keys
14.4 X.509 Certificates
14.5 Public Key Infrastructure
14.6 Recommended Reading and Web Sites
14.7 Key Terms and Review Questions
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Course Outline
Chapter 15 User Authentication Protocols
15.1 Remote User Authentication Principles
15.2 Remote User Authentication Using Symmetric
Encryption
15.3 Kerberos
15.4 Remote User Authentication Using Asymmetric
Encryption
15.5 Federated Identity Management
15.6 Recommended Reading and Web Sites
15.7 Key Terms and Review Questions
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Course Outline
PART FIVE NETWORK AND INTERNET
SECURITY
Chapter 16 Transport-Level Security
16.1 Web Security Issues
16.2 Secure Sockets Layer (SSL)
16.3 Transport Layer Security (TLS)
16.4 HTTPS
16.5 Secure Shell (SSH)
16.6 Recommended Reading and Web Sites
16.7 Key Terms and Review Questions
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Course Outline
Chapter 17 Wireless Network Security
17.1 IEEE 802.11 Wireless LAN Overview
17.2 IEEE 802.11i Wireless LAN Security
17.3 Wireless Application Protocol Overview
17.4 Wireless Transport Layer Security
17.5 WAP End-to-End Security
17.6 Recommended Reading and Web Sites
17.7 Key Terms and Review Questions
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Course Outline
Chapter 18 Electronic Mail Security
18.1 Pretty Good Privacy (PGP)
18.2 S/MIME
18.3 Domain Keys Identified Mail (DKIM)
18.4 Recommended Web Sites
18.5 Key Terms and Review Questions
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Course Outline
Chapter 19 IP Security
19.1 IP Security Overview
19.2 IP Security Policy
19.3 Encapsulating Security Payload
19.4 Combining Security Associations
19.5 Internet Key Exchange
19.6 Cryptographic Suites
19.7 Recommended Reading and Web Sites
19.8 Key Terms and Review Questions
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Chapter 0 – Reader’s Guide
The art of war teaches us to rely not on the
likelihood of the enemy's not coming, but on
our own readiness to receive him; not on the
chance of his not attacking, but rather on the
fact that we have made our position
unassailable.
—The Art of War, Sun Tzu
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Roadmap
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Cryptographic algorithms
Mutual Trust
Network Security
Computer Security
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Roadmap
• Cryptographic algorithms: Study of
techniques for ensuring the secrecy and/or
authenticity of information
• Three main areas of study in this category are:
1. symmetric encryption,
2. asymmetric encryption,
3. cryptographic hash functions, with the
related topics of message authentication codes
and digital signatures.
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Roadmap
• Mutual trust: Study of techniques and
algorithms for providing mutual trust in two
main areas.
• First, key management and distribution deals
with establishing trust in the encryption keys
used between two communicating entities.
• Second, user authentication deals with
establish trust in the identity of a
communicating partner.
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Roadmap
• Network security: Covers the use of
cryptographic algorithms in network protocols
and network applications.
• Computer security: The term refer to the
security of computers against intruders (e.g.,
hackers) and malicious software (e.g., viruses).
• Typically, the computer to be secured is
attached to a network and the bulk of the
threats arise from the network.
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Standards Organizations
• National Institute of Standards & Technology
(NIST)
• Internet Society (ISOC)
• International Telecommunication Union
Telecommunication Standardization Sector
(ITU-T)
• International Organization for Standardization
(ISO)
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Chapter 1 – Introduction
• The combination of space, time, and strength
that must be considered as the basic elements
of this theory of defense makes this a fairly
complicated matter. Consequently, it is not
easy to find a fixed point of departure..
— On War, Carl Von Clausewitz
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Computer Security
• the protection afforded to an automated
information system in order to attain the
applicable objectives of preserving the
integrity, availability and confidentiality of
information system resources (includes
hardware, software, firmware,
information/data, and telecommunications)
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Key Security Concepts
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CIA Triad
• These three concepts form what is often
referred to as the CIA triad Figure above.
• The three concepts embody the fundamental
security objectives for both data and for
information and computing services.
• FIPS PUB 199 provides a useful
characterization of these three objectives in
terms of requirements and the definition of a
loss of security in each category.
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CIA Triad
• Confidentiality (covers both data
confidentiality and privacy):
• preserving authorized restrictions on
information access and disclosure, including
means for protecting personal privacy and
proprietary information.
• A loss of confidentiality is the unauthorized
disclosure of information.
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CIA Triad
• Integrity (covers both data and system
integrity):
• Guarding against improper information
modification or destruction, and includes
ensuring information non-repudiation and
authenticity.
• A loss of integrity is the unauthorized
modification or destruction of information.
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CIA Triad
• Availability: Ensuring timely and reliable
access to and use of information. A loss of
availability is the disruption of access to or use
of information or an information system.
• Although the use of the CIA triad to define
security objectives is well established, some in
the security field feel that additional concepts
are needed to present a complete picture.
• Two of the most commonly mentioned are:
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CIA Triad
• Authenticity: The property of being genuine
and being able to be verified and trusted;
confidence in the validity of a transmission, a
message, or message originator.
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CIA Triad
• Accountability: The security goal that
generates the requirement for actions of an
entity to be traced uniquely to that entity.
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Levels of Impact
• can define 3 levels of impact from a security
breach
– Low
– Moderate
– High
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Levels of Impact
• Low: The loss could be expected to have a
limited adverse effect on organizational
operations, organizational assets, or
individuals.
• A limited adverse effect means that, for
example, the loss of confidentiality, integrity,
or availability might causes effect.
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Levels of Impact
• degradation in mission capability to an extent
and duration that the organization is able to
perform its primary functions, but the
effectiveness of the functions is noticeably
reduced;
• result in minor damage to organizational
assets;
• result in minor financial loss; or
• result in minor harm to individuals.
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Levels of Impact
• Moderate: The loss could be expected to have
a serious adverse effect on organizational
operations, organizational assets, or
individuals. A serious adverse effect means
that, for example, the loss might
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Levels of Impact
• cause a significant degradation in mission
capability and effectiveness of the functions is
significantly reduced;
• result in significant damage to oganizational
assets;
• result in significant financial loss; or
• result in significant harm to individuals that
does not involve loss of life or serious, lifethreatening injuries.
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Levels of Impact
• High: The loss could be expected to have a
severe or catastrophic adverse effect on
organizational operations, organizational
assets, or individuals. A severe or catastrophic
adverse effect means that, for example, the
loss might
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Levels of Impact
• cause a severe degradation in or loss of
mission capability to an extent and duration
that the organization is not able to perform one
or more of its primary functions;
• result in major damage to organizational
assets;
• result in major financial loss; or
• result in severe or catastrophic harm to
individuals involving loss of life or serious life
threatening injuries.
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Examples of Security
Requirements
• confidentiality – student grades
• integrity – patient information
• availability – authentication service
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Examples of Security
Requirements
• confidentiality – student grades
• integrity – patient information
• availability – authentication service
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Confidentiality Example
• Student grade information is an asset whose
confidentiality is considered to be highly
important by students.
• Grade information should only be available to
students, their parents, and employees that
require the information to do their job.
• Student enrollment information may have a
moderate confidentiality rating.
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Confidentiality Example
• While still covered by FERPA, this
information is seen by more people on a daily
basis, is less likely to be targeted than grade
information, and results in less damage if
disclosed.
• Directory information, such as lists of students
or faculty or departmental lists, may be
assigned a low confidentiality rating.
• Freely available to the public and published on
a school's Web site.
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Integrity Example
• Consider a hospital patient's allergy
information stored in a database.
• The doctor should be able to trust that the
information is correct and current.
• Now suppose that an employee (e.g., a nurse)
who is authorized to view and update this
information deliberately falsifies the data to
cause harm to the hospital.
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Integrity Example
• The database needs to be restored to a trusted
basis quickly, and it should be possible to trace
the error back to the person responsible.
• Patient allergy information is an example of an
asset with a high requirement for integrity.
• Inaccurate information could result in serious
harm or death to a patient and expose the
hospital to massive liability.
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Availability Example
• The more critical a component or service, the
higher is the level of availability required.
• Consider a system that provides authentication
services
• An interruption of service results in the
inability for customers to access computing
resources.
• loss of service translates into a large financial
loss productivity and potential customer loss.
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Computer Security Challenges
not simple
2. must consider potential attacks
3. procedures used counter-intuitive
4. involve algorithms and secret info
5. must decide where to deploy mechanisms
6. battle of wits between attacker / admin
7. not perceived on benefit until fails
8. requires regular monitoring
9. too often an after-thought
10. regarded as impediment to using system
1.
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OSI Security Architecture
• ITU-T X.800 “Security Architecture for OSI”
• defines a systematic way of defining and
providing security requirements
• for us it provides a useful, if abstract, overview
of concepts we will study
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Aspects of Security
• consider 3 aspects of information security:
– security attack
– security mechanism
– security service
• note terms
– threat – a potential for violation of security
– attack – an assault on system security, a deliberate
attempt to evade security services
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Aspects of Security
• Security attack: Any action that compromises
the security of information owned by an
organization.
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Aspects of Security
• Security mechanism: A process (or a device
incorporating such a process) that is designed
to detect, prevent, or recover from a security
attack.
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Aspects of Security
• Security service: A processing or
communication service that enhances the
security of the data processing systems and the
information transfers of an organization.
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Passive Attacks
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Passive Attacks
• A useful means of classifying security attacks, used both
in X.800 and RFC 2828, is in terms of passive attacks
and active attacks.
• A passive attack attempts to learn or make use of
information from the system but does not affect system
resources.
• Passive attacks are in the nature of eavesdropping on, or
monitoring of, transmissions. The goal of the opponent is
to obtain information that is being transmitted.
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Passive Attacks
• Two types of passive attacks are:
+ release of message contents
+ traffic analysis - monitor traffic flow to determine location
and identity of communicating hosts and could observe the
frequency and length of messages being exchanged
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Active Attacks
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Active Attacks
• Active attacks involve some modification of
the data stream or the creation of a false stream
• can be subdivided into four categories:
• masquerade of one entity as some other
• replay previous messages
• modify/alter (part of) messages in transit to
produce an unauthorized effect
• denial of service - prevents or inhibits the
normal use or management of
communications facilities
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Active Attacks
• Active attacks present the opposite characteristics
of passive attacks.
• Whereas passive attacks are difficult to detect,
measures are available to prevent their success.
• Quite difficult to prevent active attacks absolutely,
because of the wide variety of potential physical,
software, and network vulnerabilities.
• Instead, the goal is to detect active attacks and to
recover from any disruption/or delays caused by
them.
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Security Service
– enhance security of data processing systems and
information transfers of an organization
– intended to counter security attacks
– using one or more security mechanisms
– often replicates functions normally associated with
physical documents
• which, for example, have signatures, dates; need
protection from disclosure, tampering, or destruction; be
notarized or witnessed; be recorded or licensed
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Security Services
• X.800:
“a service provided by a protocol layer of
communicating open systems, which ensures
adequate security of the systems or of data
transfers”
• RFC 2828:
“a processing or communication service provided by
a system to give a specific kind of protection to
system resources”
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Security Services (X.800)
• Authentication - assurance that communicating
entity is the one claimed
– have both peer-entity & data origin authentication
• Access Control - prevention of the unauthorized use
of a resource
• Data Confidentiality –protection of data from
unauthorized disclosure
• Data Integrity - assurance that data received is as
sent by an authorized entity
• Non-Repudiation - protection against denial by one
of the parties in a communication
• Availability – resource accessible/usable
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Security Mechanism
• feature designed to detect, prevent, or recover
from a security attack
• no single mechanism that will support all
services required
• however one particular element underlies
many of the security mechanisms in use:
– cryptographic techniques
• hence our focus on this topic
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Security Mechanisms (X.800)
• specific security mechanisms:
– encipherment, digital signatures, access controls,
data integrity, authentication exchange, traffic
padding, routing control, notarization
• pervasive security mechanisms:
– trusted functionality, security labels, event
detection, security audit trails, security recovery
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Model for Network Security
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Model for Network Security
•
using this model requires us to:
1. design a suitable algorithm for the security
transformation
2. generate the secret information (keys) used by
the algorithm
3. develop methods to distribute and share the
secret information
4. specify a protocol enabling the principals to use
the transformation and secret information for a
security service
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Model for Network Access Security
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Model for Network Access Security
•
using this model requires us to:
1. select appropriate gatekeeper functions to
identify users
2. implement security controls to ensure only
authorised users access designated information or
resources
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Summary
• Outline of the course is discussed
• topic roadmap & standards organizations
• security concepts:
– confidentiality, integrity, availability
• X.800 security architecture
• security attacks, services, mechanisms
• models for network (access) security
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