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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**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 P _{r}[xly]= P_{r}[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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**7. Consider one bit encryption C = P┬оK 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.

### COURSE LAYOUT

**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.

**CRITERIA TO GET A CERTIFICATE**

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.**