1. Data Security and Encryption (CSE348) 1

2. Dr. Basit Raza Assistant Professor Comsats Institute of Information Technology, Islamabad 2

3. Course Outline In this course we will follow the mentioned book Cryptography and Network Security”, 5 th Edition by William Stallings. The book is organized into seven parts: 3

4. 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. 4

5. Course Outline Part Two: Asymmetric Ciphers: Provides a survey of public-key algorithms, including RSA (Rivest-Shamir-Adelman) and elliptic curve. 5

6. 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. 6

7. Course Outline Part Four: Mutual Trust: Covers key management and key distribution topics and then covers user authentication techniques. 7

8. 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. 8

9. 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. 9

10. Course Outline Part Seven: Legal and Ethical Issues: Deals with the legal and ethical issues related to computer and network security. 10

11. 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 11

12. 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 12

13. 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 13

14. 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 14

15. 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 15

16. 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 16

17. 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 17

18. 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 18

19. 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 19

20. 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 20

21. 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 21

22. 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 22

23. 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 23

24. 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 24

25. 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 25

26. 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 26

27. 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 27

28. 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 28

29. 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 29

30. 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 30

31. Roadmap Cryptographic algorithms Mutual Trust Network Security Computer Security 31

32. 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. 32

33. 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. 33

34. 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. 34

35. Standards Organizations National Institute of Standards & Technology (NIST) Internet Society (ISOC) International Telecommunication Union Telecommunication Standardization Sector (ITU-T) International Organization for Standardization (ISO) 35

36. 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 36

37. 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) 37

38. Key Security Concepts 38

39. CIA Triad 39 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.

40. CIA Triad 40 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.

41. CIA Triad 41 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.

42. CIA Triad 42 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:

43. CIA Triad 43 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.

44. CIA Triad 44 Accountability: The security goal that generates the requirement for actions of an entity to be traced uniquely to that entity.

45. Levels of Impact can define 3 levels of impact from a security breach – Low – Moderate – High 45

46. 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. 46

47. 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. 47

48. 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 48

49. 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, life- threatening injuries. 49

50. 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 50

51. 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. 51

52. Examples of Security Requirements confidentiality – student grades integrity – patient information availability – authentication service 52

53. Examples of Security Requirements confidentiality – student grades integrity – patient information availability – authentication service 53

54. 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. 54

55. 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. 55

56. 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. 56

57. 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. 57

58. 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. 58

59. Computer Security Challenges 1. 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 59

60. 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 60

61. 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 61

62. Aspects of Security Security attack: Any action that compromises the security of information owned by an organization. 62

63. 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. 63

64. 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. 64

65. Passive Attacks 65

66. Passive Attacks 66 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.

67. Passive Attacks 67 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

68. Active Attacks 68

69. Active Attacks 69 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

70. Active Attacks 70 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.

71. 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 71

72. 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” 72

73. 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 73

74. 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 74

75. 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 75

76. Model for Network Security 76

77. 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 77

78. Model for Network Access Security 78

79. 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 79

80. 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 80