Cryptographic Hash Functions: Message Authentication, Secure Hash Algorithm (SHA-512), Message authentication codes: Authentication requirements, HMAC, CMAC, Digital signatures, Elgamal Digital Signature Scheme. Key Management and Distribution: Symmetric Key Distribution Using Symmetric & Asymmetric Encryption, Distribution of Public Keys, Kerberos, X.509 Authentication Service, Public – Key Infrastructure

1. CRYPTOGRAPHY & NETWORK
SECURITY- Cryptographic Hash
Functions
Dr R Jegadeesan Prof-CSE
Jyothishmathi Institute of Technology and Science,
karimnagar

2. Cryptographic Hash Functions
Syllabus
➢UNIT – III: Cryptographic Hash Functions: Message Authentication, Secure
Hash Algorithm (SHA-512), Message authentication codes: Authentication
requirements, HMAC, CMAC, Digital signatures, Elgamal Digital Signature
Scheme. Key Management and Distribution: Symmetric Key Distribution Using
Symmetric & Asymmetric Encryption, Distribution of Public Keys, Kerberos,
X.509 Authentication Service, Public – Key Infrastructure
Security Introduction
2

3. Cryptographic Hash Functions
Aim & Objective :
➢ Our focus is on Internet Security
➢ Consists of message authentication code
➢UNIT – III: Cryptographic Hash Functions: Message Authentication, Secure
Hash Algorithm (SHA-512), Message authentication codes: Authentication
requirements, HMAC, CMAC, Digital signatures, Elgamal Digital Signature
Scheme. Key Management and Distribution: Symmetric Key Distribution Using
Symmetric & Asymmetric Encryption, Distribution of Public Keys, Kerberos,
X.509 Authentication Service, Public – Key Infrastructure
Security Introduction
3

4. Cryptographic Hash Functions

5. Message Authentication
It is a mechanism or service used to verify the
integrity of a message.
Procedure to verify that
- Received message is from alleged source.
- Message has not been altered.
- There is no change in message sequence.
- Message is not delayed or a replay.
Cryptographic Hash Functions

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8. Message Authentication Functions
• Any message authentication or digital signature
mechanism has two levels of functionality.
• At the lower level, there must be some sort of
function that produces an authenticator: a value to
be used to authenticate a message.
• This lower-level function is then used as a primitive
in a higher-level authentication protocol that
enables a receiver to verify the authenticity of a
message.
Cryptographic Hash Functions

9. Types of Message Authentication Functions
The types of functions that may be used to produce an
authenticator.
These may be grouped into three classes.
• Message encryption: The cipher text of the entire
message serves as its authenticator.
• Message authentication code (MAC): A function of
the message and a secret key that produces a fixed-
length value that serves as the authenticator.
• Hash function: A function that maps a message of
any length into a fixed length hash value, which
serves as the authenticator.
Cryptographic Hash Functions

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23. Hash Function courses
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courses available on <www.coursera.org>, and http://neat.aicte-india.org
https://www.coursera.org/
Course 1 : Introduction to Cyber Security
Cyber Security. An introduction to modern information and system protection technology and methods.
Course 2: Cyber security Specialization
-Cyber security Fundamentals. Construction of Secure Systems
Cryptographic Hash Functions

24. Security Tutorials
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Tutorial topic wise
➢Cryptography Tutorial – Tutorialspoint www.tutorialspoint.com › cryptography
➢Cryptography Introduction – GeeksforGeeks www.geeksforgeeks.org › cryptography-introduction
➢www.cse.iitm.ac.in › ~chester › courses › slides › 01_Introduction
Cryptographic Hash Functions

25. Network Security MCQs
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CNS – MCQs
1.ECB stands for
a. Electronic Control Book b. Electronic Code Book
c. Electronic Cipher Book d. Electronic Cryptography Book
2.The process of transforming plain text to unreadable text.
a. Decryption b. Encryption
c. Network Security d. Information Hiding
3.Plain text is the data after encryption is performed.
a. True b. False c. May be d. Can't say
4.Study of creating a d using encryption and decryption techniques.
a. Cipher b. Cryptography
b. c. Encryption d. Decryption
5. An attack in which the user receives unwanted amount of e-mails.
a. Smurfing b. Denial of service
c. E-mail bombing d. Ping storm
Cryptographic Hash Functions

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CNS –Tutorial Problems:
❑There are many businesses that don’t have a complete inventory of all of the IT assets that they have tied into
their network. This is a massive problem. If you don’t know what all of the assets are on your network, how can
you be sure your network is secure?
❑Many businesses are concerned with “zero day” exploits. These exploits are those unknown issues with security in
programs and systems that have yet to be used against anyone. However, zero day vulnerabilities aren’t the
problem—unpatched known vulnerabilities are the problem.
Cryptographic Hash Functions

27. CNS Questions
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Universities & Important Questions:
1. Differentiate MAC and Hash function.
2. Define hash function.
3. What is a Message Authentication Code (MAC)?
4. Define weak-collision resistance.
5. Define strong-collision resistance
6. Define digital Signature.
7. What is the difference between direct and arbitrated digital signature?
8. What is the role of a Key Distribution Centre (KDC) for user authentication?
9. What is the role of a nonce while using an authentication protocol?
10. What is called public key certificate?
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Thank you