Cryptography And Network Security Assignment 2 Answers 2022

NPTEL Cryptography And Network Security Assignment 2 Answers 2022:- In this post, We have provided answers of NPTEL Cryptography And Network Security Assignment 2. We provided answers here only for reference. Plz, do your assignment at your own knowledge.

NPTEL Cryptography And Network Security Assignment 2 Answers 2022 [July-Dec]

Q1. What is the size of plaintext in Data Encryption Standard(DES)?

(a) 28
(b) 54
(c) 64
(d) 92

Answer:- c

Q2. DES is a rOund Feistel cipher having block length ..

(a) 16,64
(b) 8,56
(c) 16,16
(d) 16,32

Answer:- a

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Cryptography And Network Security Assignment 2 Answers 2022

3. What kind of cipher DES is ?

(a) block cipher
(b) stream cipher
(c) bit cipher
(d) permutation cipher

Answer:- a

4. A cryptosystem has perfect secrecy if Pr[xly]= Pr[x] for all X E P, y E C, where P and C are the plaintext space and ciphertext space respectively. The above statement is ..

(a) True
(b) False

Answer:- a 

5. For a stream cipher, the plaintext and the key are given by 1000 and 0100, respectively. Then the ciphertext is .

(a) 1111
(b) 0000
(c) 1100
(d) 0011

Answer:- c

6. What is the size of output produced by each S-box in DES algorithm?

(a) 8
(b) 4
(c) 2
(d) 16

Answer:- b

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Cryptography And Network Security Assignment 2 Answers 2022

7. Consider one bit encryption C = P®K and Pr(K = 0) = Pr(K = 1) = 0.5, Pr(P = 0) = 0.6, Pr(P = 1) = 0.4. Then Pr(P= 0|C = 1) 1S ….

(a) 0.5
(b) 0.4
(c) 0.6
(d) None of these

Answer:- c

8. How many rounds a Data Encryption Standard (DES) system has with an initial and final permutation block?

(a) 16
(b) 8
(c) 32
(d) None of these

Answer:- a

9. One-time pad possesses perfect secrecy. The above statement is…

(a) True
(b) False

Answer:- a

10. The key size of DES is ..

(a) 48
(b) 32
(c) 64
(d) 56

Answer:- d

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About Cryptography And Network Security

The aim of this course is to introduce the student to the areas of cryptography and cryptanalysis. This course develops a basic understanding of the algorithms used to protect users online and to understand some of the design choices behind these algorithms. Our aim is to develop a workable knowledge of the mathematics used in cryptology in this course. The course emphasizes to give a basic understanding of previous attacks on cryptosystems with the aim of preventing future attacks. A wide variety of basic cryptographic primitives will be discussed along with recent developments in some advanced topics like identity-based encryption, attribute-based encryption, functional encryption, two-party/multi-party computation, bitcoin and crypto-currency and postquantum cryptography. The cryptanalysis part will help us understanding challenges for cybersecurity that includes network security, data security, mobile security, cloud security and endpoint security. 


  • Week 1: Introduction to cryptography, Classical Cryptosystem, Block Cipher. 
  • Week 2: Data Encryption Standard (DES), Triple DES, Modes of Operation, Stream Cipher. 
  • Week 3: LFSR based Stream Cipher, Mathematical background, Abstract algebra, Number Theory. 
  • Week 4: Modular Inverse, Extended Euclid Algorithm, Fermat’s Little Theorem, Euler Phi-Function, Euler’s theorem. 
  • Week 5: Advanced Encryption Standard (AES), Introduction to Public Key Cryptosystem, Diffie-Hellman Key Exchange, Knapsack Cryptosystem, RSA Cryptosystem. 
  • Week 6: Primarily Testing, ElGamal Cryptosystem, Elliptic Curve over the Reals, Elliptic curve Modulo a Prime. 
  • Week 7: Generalized ElGamal Public Key Cryptosystem, Rabin Cryptosystem. 
  • Week 8 : Message Authentication, Digital Signature, Key Management, Key Exchange, Hash Function. 
  • Week 9 : Cryptographic Hash Function, Secure Hash Algorithm (SHA), Digital Signature Standard (DSS). 
  • Week 10: Cryptanalysis, Time-Memory Trade-off Attack, Differential and Linear Cryptanalysis. 
  • Week 11: Cryptanalysis on Stream Cipher, Modern Stream Ciphers, Shamir’s secret sharing and BE, Identity-based Encryption (IBE), Attribute-based Encryption (ABE). 
  • Week 12: Side-channel attack, The Secure Sockets Layer (SSL), Pretty Good Privacy (PGP), Introduction to Quantum Cryptography, Blockchain, Bitcoin and Cryptocurrency.  


Average assignment score = 25% of average of best 8 assignments out of the total 12 assignments given in the course.
Exam score = 75% of the proctored certification exam score out of 100

Final score = Average assignment score + Exam score

YOU WILL BE ELIGIBLE FOR A CERTIFICATE ONLY IF AVERAGE ASSIGNMENT SCORE >=10/25 AND EXAM SCORE >= 30/75. If one of the 2 criteria is not met, you will not get the certificate even if the Final score >= 40/100.

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