NPTEL Cryptography And Network Security Assignment 1 Answers 2022:- In this post, We have provided answers of NPTEL Cryptography And Network Security Assignment 1. We provided answers here only for reference. Plz, do your assignment at your own knowledge.

## NPTEL Cryptography And Network Security Assignment 1 Answers 2022 [July-Dec]

Q1. A traditional cryptosystem consists of.

(a) three tuple.

(b) four tuple.

(c) five tuple.

(d) six tuple.

Answer:-c

**2. Let P,C, K denote plaintext space, ciphertext space and key space re- spectively. In Shift Cipher, P = C = K = Z26. If the key for Shift Cipher is k = 12 and plaintext is 21 then ciphertext is **

(a) 6

(b) 7

(c) 8

(d) 9

Answer:-b

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**3. Caesar Cipher is an example of **

(a) Poly-alphabetic Cipher

(b) Mono0-alphabetic Cipher

(c) both (a) and (b)

(d) neither (a) nor (b)

Answer:-b

**4. Shift cipher is secure. The above statement is ... **

(a) True

(b) False

Answer:-b

**5. The key-space for vigenere cipher of length m (mn is a positive integer) S **

(a) (Z2n)

(b) (Z)”

(c) Z

(d) None of the above

Answer:-a

**6. Which are the most frequently found letters in the English language ? **

(a) e,a

(b) e,o

(c) e,t

(d) ei

Answer:-c

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**7. If the sender and receiver use different keys, the system is referred to as **

(a) symmetric system.

(b) asymmetric system.

(c) none of these.

Answer:-b

8. ……………………………….. is the concept that tells us about the replacement of every alphabet and the entire series gets ‘shifted’ by some fixed quantity.

(a) Block cipher.

(b) Playfair cipher.

(c) Vegenere cipher

(d) Shift cipher.

Answer:-d

9. Suppose the ciphertext for caeser cipher is “SDUWB”. Which of the following is the corresponding plaintext?

(a) parti

(b) block

(c) party

(d) none of these.

Answer:-c

10. Cryptography works for

(a) only Entity authentication

(b) only Non repudiation of message

(c) only Confidentiality

(d) All of them.

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.**

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