Download AKTU B-Tech 8th Sem 2015-16 ECS 084 Cryptography Network Security Question Paper

Download AKTU (Dr. A.P.J. Abdul Kalam Technical University (AKTU), formerly Uttar Pradesh Technical University (UPTU) B-Tech 8th Semester (Eight Semester) 2015-16 ECS 084 Cryptography Network Security Question Paper

Printed Pages: 4 ECS-084
(Following Paper ID and Roll No. to be ?lled in your
Answer Books)
PaperID:110854 RollN0.| | | | | | I | I I
B.TECH.
Theory Examination (Semester?VIII) 2015-16
CRYPTOGRAPHY & NETWORK SECURITY
T ime : 3 Hours Max. Marks : 100
Note : Attempt questions from all Sections as per directions.
Section-A
Attempt all parts of this section. Answer in brief.
(2X10=20)
Q1. (a) Find gcd (1970, 1066) using Euclid?s algorithm?
(b) Using Row Transposition technique & given key as
"2 5 4 1 3" generate the Cipher Text for the following
plain text "a convenient way to express the transpo-
sition".
(0) Perform encryption and decryption using RSA Algo-
rithm for the following.
P=7; q=11; e=17; M=8.
(1) P.T.O.
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(d)
(f)
(g)
(h)
(i)
What are the design parameters of Feistel cipher net-
work?
Using Playfair technique, encrypt the following message
"send more money" using the key - "tarun".
What is the difference between Shift Rows and Rot
Word?
Brie?y describe Add Round Key.
What are the two problems with one-time pad?
Deline the classes of message authentication function.
Explain in brief Symmetric and Asymmetric cryptogra-
phy-
Section-B
2. Attempt any ?ve questions from this section. (10X5=50)
(a) If n is composite and passes the Miller?Rabin (MR) piimarily
test for the base a. then 11 is called strong pseudo prime t0 the
base a. Show that 2047 is strong pseudo prime t0 the base 2.
(2)
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(b)
(C)
(d)
(6)
(f)
(g)
(11)
What do you mean by Security Association? Specify the pa-
rameters that identify the Security Association? Explain man in
the middle attack?
What is the key algorithms used in S/MIME? What are the
headers ?elds de?ne in MME?
Differentiate MAC and Hash function. Assume the client C
wants to communicate server S using Kerberos procedure.
How can it be achieved?
What is message authentication code? How it differs ?om hash
function? What are the requirements of hash function? Suggest
at least one scheme to show that symmetric encryption algo-
rithm can also be used to generate message authentication
code.
Compare and contrast a conventional ink based signature and
a digital signature. Describe the Elgamal scheme of digital sig-
nature generation and veri?cation. Why do signatures of the
same message, signed on different occasions differ?
(1) Explain the Chinese Remainder Theorem. Use it to
solve: X=2 mod 3, X=3 mod 5 and X=2 mod 7.
(ii) State and prove Fermat's theorem.
Why do we use X509 authentication over PKC based au-
thentication. Also explain the format of X509 and how is an
X509 certi?cate revoked?
(3 P.T.O.
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Section-C
Attempt any two questions from this section. (15X2=30)
3. Discuss symmetric key distnbution. Also descnbe Di?ie?Hellman
Key exchange algorithm. Consider the Dif?e-Hellman scheme
with common prime number q=71 and primitive root a=7 :
(a) If user A has a private key Xa=5, what is A?s public
key.
(b) If the user A has private key Xb=9 then what is B?s
public key?
(c) What is shared key?
4. What is DSS? Explain the two approaches of DSS. Also dif-
ferentiate between ink based signature and digital signature.
Explain DSA algorithm.
5. Explain the following:
(i) ICMP
(ii) IGMP
(iii) ARP
(iv) FDDI
(4)
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