Date : 16.02.2015

1. Subject Name: NETWORK SECURITY Subject Code: 10EC832 Prepared By: SHAIK KAREEMULLA & BENJAMIN I Department: ELECTRONICS AND COMMUNICATION ENGINEERING Engineered for Tomorrow Prepared by : Kareemulla & Benjamin Department : Electronics and Communication Engg Date : 16.02.2015

2. UNIT I 1/2/2020

3. TOPICS TO BE COVERED: Services, Mechanisms, Mechanism Attacks, The OSI security architecture, A model for network security. (6 Hrs)

4. 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)

5. Key Security Concepts

6. Three Key Objectives • Confidentiality • Data confidentiality • Privacy • Integrity • Data integrity • System integrity • Availability • Additional concepts • Authenticity • Accountability

7. Levels of Impact • 3 levels of impact from a security breach • Low • Moderate • High

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

9. Computer Security Challenges not simple must consider potential attacks procedures used counter-intuitive involve algorithms and secret info must decide where to deploy mechanisms battle of wits between attacker / admin not perceived on benefit until fails requires regular monitoring too often an after-thought regarded as impediment to using system

10. 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

11. Aspects of Security • 3 aspects of information security: • security attack • security mechanism: detect, prevent, recover • security service • terms • threat – a potential for violation of security • attack – an assault on system security, a deliberate attempt to evade security services

12. Passive Attacks (1)Release of Message Contents

13. Passive Attacks (2)Traffic Analysis

14. Passive attacks do not affect system resources • Eavesdropping, monitoring • Two types of passive attacks • Release of message contents • Traffic analysis • Passive attacks are very difficult to detect • Message transmission apparently normal • No alteration of the data • Emphasis on prevention rather than detection • By means of encryption

15. Active Attacks (1)Masquerade

16. Active Attacks (2)Replay

17. Active Attacks (3)Modification of Messages

18. Active Attacks (4)Denial of Service

19. Active attacks try to alter system resources or affect their operation • Modification of data, or creation of false data • Four categories • Masquerade • Replay • Modification of messages • Denial of service: preventing normal use • A specific target or entire network • Difficult to prevent • The goal is to detect and recover

20. 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

21. 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”

22. 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

23. 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

24. Security Mechanisms • 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

26. Model for Network Security

27. Model for Network Security • using this model requires us to: • design a suitable algorithm for the security transformation • generate the secret information (keys) used by the algorithm • develop methods to distribute and share the secret information • specify a protocol enabling the principals to use the transformation and secret information for a security service

28. Model for Network Access Security

29. Model for Network Access Security • using this model requires us to: • select appropriate gatekeeper functions to identify users • implement security controls to ensure only authorised users access designated information or resources

30. Standards • NIST: National Institute of Standards and Technology • FIPS: Federal Information Processing Standards • SP: Special Publications • ISOC: Internet Society • Home for IETF (Internet Engineering Task Force) and IAB (Internet Architecture Board) • RFCs: Requests for Comments

31. Summary • topic roadmap & standards organizations • security concepts: • confidentiality, integrity, availability • security architecture • security attacks, services, mechanisms • models for network (access) security

32. Exercise 1. Write a note on security Services. 2. Explain Security Mechanisms. 3. What are the types of security attacks? Explain in details. 4. What are things on which OSI security model focuses? 5. With a block diagram explain network security model in detail.

33. UNIT -2SYMMETRIC CIPHER MODEL

34. Contents • INTRODUCTION • CRYPTOGRAPHY • NEED FOR SECURITY • SYMMETRIC CIPHER MODEL • MODEL OF CONVENTIONAL CRYPTOSYSTEM • THE DATA ENCRYPTION STANDARD • DES ENCRYPTION ALGORITHM • (DES3) TRIPLE DATA ENCRYPTION STANDARD • APPLICATIONS • CONCLUSION (7 Hrs)

35. INTRODUCTION • Power analysis attacks have attracted significant attention within the cryptographic community. So far, they have been successfully applied to different kinds of (unprotected) symmetric and public-key encryption schemes. • In Boolean Masking has been successfully applied to smart card implementations of the DES and the AES . • The protected algorithms usually have much higher memory requirements than the unmasked ones. For this reason, it is often assumed that masking is not a practical solution for the protection of hardware implementations.

36. CRYPTOGRAPHY • Cryptography is the study of mathematical techniques related to aspects of information security such as confidentiality, data integrity, entity authentication, and origin authentication. • There are two kinds of cryptosystems: 1.symmetric 2.asymmetric • Symmetric cryptosystems use the same key (the secret key) to encrypt and decrypt a message. • Asymmetric cryptosystems use one key (the public key) to encrypt a message and a different key (the private key) to decrypt it. Asymmetric cryptosystems are also called public key cryptosystems.

37. Need for security • Steps involved in secured communication: 1. Design an algorithm for performing the security related transformation such that the opponent cannot defeat its purpose. 2. Generate the secret information to be used with the algorithm. 3. Specify the protocol to be used by the two principles that make use of the security algorithm. Threats in communication • Information access threat: Modification of the data without the knowledge of sender and then transmit the data. • Service threat: Exploit this flaws in the services available in computer to inhibit the use by legitimate users.

38. Decryption Process Encryption Process SYMMETRIC CIPHER MODEL Secret key shared by Secret key shared by sender and recipient sender and recipient Transmitted Cipher text Plaintext input Encryption Algorithm e.g.: TDES Decryption Algorithm Plaintext output (reverse of Encryption Algorithm) Simplified Model of Conventional Encryption

39. MODEL OF CONVENTIONAL CRYPTOSYSTEM

40. THE DATA ENCRYPTION STANDARD • DES is the most widely used symmetric algorithm in the world, because the key length is too short. Since DES was first announced, controversy has raged about whether 56 bits is long enough to guarantee security. • Just applying DES twice, double DES, is ineffective. Using two 56-bit keys gives 112 total key bits, so a brute force attack needs 2111 encryptions. However, brute force is not the best attack. • Advanced Encryption Standard (AES) will be at least as strong as Triple DES and probably much faster.

42. Limitations of DES • Generating the per-round keys that the key is subjected to an a initial permutation to generate two 28 – bit quantities C0 and D0. The sixteen suspect keys are ones for which , C0 and D0 are one of the four values : all ones , all zeroes , alternating ones and zeroes , alternating zeroes and ones . Since there are four possible values for each half , there are sixteen possibilities in all. • The four weak keys are the ones for which each of , C0 and D0 are all ones or all zeroes. Weak keys are their own inverses. The remaining twelve keys are the semi- weak keys. Each is the inverse of one of the others.

43. Applications of DES The DES core can be utilized for a variety of encryption applications including: • Secure File/Data transfer • Electronic Funds Transfer • Encrypted Storage Data • Secure communications Features of DES • Encryption/Decryption performed in 16 cycles (ECB mode) • 56 bits of security • For use in FPGA designs • Verilog IP Core

44. (DES3) Triple Data Encryption Standard • The DES3 core is a block cipher, working on 64 bits of data at a time. It is built upon the Data Encryption Standard (DES) core. Key length is 64 bits of which only 56 bits are used. • The DES3 Low Gate version is implemented to minimize gate • count or FPGA resources. The design does not use any memories such as SRAM.  • The DES3 Pipelined version is implemented to maximize performance by pipelining the DES algorithm through three DES-PL instantiations. 

45. TDES Encryption TDES Decryption

46. DES ENCRYPTION ALGORITHM

47. INPUT 64 BIT BLOCK DIAG FOR INPUT DATA KEY 48 BITS INITIAL PERMUTATION LEFT 32 BITS RIGHT 32 BITS S-BOX 32 bits EXPANSION PERMUTATION 48 bits 48 bits XOR 32 bits XOR PERMUTATION BOX 32 bits 32 bits 32 bits Ri Li

48. 8 BITS FOR PARITY 56 BITS INPUT 64 BIT PERMUTATION CHOICE(PC1) BLOCK DIAGRAM FOR KEY GENERATION 56 BITS 48 BIT KEY PERMUTATION CHOICE(PC2) 48 bits S-BOX EXPANSION PERMUTATION 48 bits 48 bits XOR

49. Single Round of DES

50. Initial permutation (IP) Table- Initial permutation