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- Cryptography And Network Security - CNS
- 2018
- PYQ
**Biju Patnaik University of Technology BPUT - BPUT**- Electronics and Communication Engineering
- B.Tech
**6906 Views**- 155 Offline Downloads
- Uploaded 11 months ago

Registration No : Total Number of Pages : 02 B.Tech. PET6J009 6th Semester Regular Examination 2017-18 CRYPTOGRAPHY & NETWORK SECURITY BRANCH : ECE, ETC Time : 3 Hours Max Marks : 100 Q.CODE : C442 Answer Part-A which is compulsory and any four from Part-B. The figures in the right hand margin indicate marks. Q1 a) b) c) d) e) f) g) h) i) j) Part – A (Answer all the questions) Answer the following questions : IDEA stands for (a) Initial Data encryption algorithm (b) International digital encryption algorithm (c) International data entity authentication (d) None of the above ECB stands for (a) Electronic code book (c) Electronic Chaining Block (b) Encrypted code book (d) Encrypted Chaining Block RSA involves very large --------- numbers. (a) Primary (c) Even (b) Odd (d) Any number Diffie- Hellman key exchange is vulnerable to -------------(a) Discrete algorithm (c) Elliptic curve cryptography (b) Man in the middle attack (d) None of these A straight permutation cipher or a straight P-box has same number of inputs as (a) Cipher (c) Frames (b) Outputs (d) Bits The first step of MD5 is __________. (a) Add padding bits to original messsge. (b) Adding append length bits. (c) Divide the input into 512 bit blocks. (d) Compression. AES encrypts data in block size of __________ bits each. (a) 64 (c) 128 (b) 32 (d) 56 __________ refers more to asymmetric key cryptography. (a) Timing attack (c) Meet in middle attack (b) Virus attack (d) Worms attack The encryption of an original message can be done __________ (a) Only once (c) twice (b) Thrice (d) many times If a document is encrypted with private key of the sender, then it can be decrypted by ____________ key. (a) Public Key of sender (c) Private key of sender (b) Private key of receiver (d) Public key of receiver (2 x 10)

Q2 a) b) c) d) e) f) g) h) i) j) Answer the following questions : Short answer type : Define Data Integrity and system integrity. What is the Second Birthday Problem?. Differentiate between passive attack and active attack. Name tow Substitution and Transposition techniques each. Define Reversible mapping Use Caesar cipher with key =12 to encrypt the message “Hello”. Solve the congruence =7 mod 11. What is meant by IP Spoofing? Define the classes of message authentication function. What you meant by MAC? Q3 a) b) Part – B (Answer any four questions) Explain the security mechanisms described in X.800. Distinguish between cryptography and steganography. Q4 a) (2 x 10) (10) (5) What are the services provided by IP Security? Describe the architecture of IP security architecture. Write briefly the categories of attacks. What are the X.800 listed attacks? (10) Differentiate between Differential cryptanalysis and Linear cryptanalysis with suitable examples. What is digital signature? Explain the RSA digital signature standard. (10) Explain the Chinese remainder theorem. Find the value of x for the congruence equations: x≡ 2 mod 7 and x≡ 3 mod 9. How do you convert a block cipher into a stream cipher by using the Cipher Feedback (CFB) mode? Explain (10) (10) b) Explain about Diffie-Hellman key exchange algorithm with one suitable example. What are the attacks that are possible on RSA? Q8 a) b) Explain the compression function used in Secure Hash Algorithm. What are the requirements of hash functions? (10) (5) Q9 a) b) Explain the four protocols defined by Secure Socket Layer. What is the need for security services at transport layer of Internet Protocol? (10) (5) b) Q5 a) b) Q6 a) b) Q7 a) (5) (5) (5) (5)

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