Special Edition for CSEDU
CSEDU Students

Students

TOUCH-N-PASS EXAM CRAM GUIDE SERIESCRYPTOGRAPHY

Prepared By

Sharafat Ibn Mollah Mosharraf
CSE, DU
12 Batch (20052005-2006)
2006)
thTable of Contents
CHAPTER 1: INTRODUCTION (STALLINGS) ......................................................................................................................... 1
CHAPTER 2: CLASSICAL ENCRYPTION TECHNIQUES (STALLINGS) ........................................................................... 1
CHAPTER 19: MALICIOUS SOFTWARE (STALLINGS) ........................................................................................................ 2
CHAPTER 30: CRYPTOGRAPHY (FOROUZAN) & CHAPTER 3 - DES, 5 – AES (STALLINGS)..................................... 2CHAPTER 31: NETWORK SECURITY (FOROUZAN)............................................................................................................. 3
CHAPTER 32: SECURITY IN THE INTERNET (FOROUZAN) .............................................................................................. 5

CHAPTER 1
INTRODUCTION
1.1

What is replay attack? Give some examples of replay attack? [2008. Marks: 1 + 1]

1.2

List and describe categories of Security Services. [2007. Marks: 5]

1.3

Distinguish between active and passive security attacks and name possible active and passivesecurity attacks. [In-course 06-07. Marks: 3]
ALSO, List the categories of active security attack and passive security attack and explain
any one active and any one passive security attack. [In-course 08-09. Marks: 2 + 3]

1.4

Illustrate and briefly explain any one of the following: [In-course 06-07. Marks: 2]
i.
ii.

1.5

Model for network security
Network access security model

Illustrate and explain the functions of each component of network security mode. [In-course08-09. Marks: 2 + 3]

CHAPTER 2
CLASSICAL ENCRYPTION TECHNIQUES
2.1

Explain Symmetric-Key cryptography model with its ingredients/elements. [2007. Marks: 4]

2.2

Briefly explain cryptanalysis and brute-force attack. [2007. Marks: 4]

2.3

What are substitution cipher and transposition cipher? Give example. [2007. Marks: 2]
ALSO, List as many substitution ciphers and as many transposition ciphers as you can andbriefly explain any one from each type. [In-course 08-09. Marks: 1 + 4]

2.4

Distinguish between stream cipher and block cipher and explain n-bit-n-bit block cipher.
[In-course 08-09. Marks: 2 + 3]

2.5

List and briefly define the types of cryptanalytic attacks based on what is known to theattacker. [In-course 08-09. Marks: 5]1

CHAPTER 19
MALICIOUS SOFTWARE
19.1

Explain the principle of operation of a compression virus, and illustrate its operation by theexecution of a virus affected program. [2006. Marks: 2 + 3]

19.2

How does a worm propagate? [2007. Marks: 2]

19.3

What is Logic Bomb? [In-course 06-07. Marks: 1]

19.4

What are the typical phases of operations of a virus? [In-course 06-07. Marks: 2]

19.5

How does Behavior Blocking Software work? [In-course 06-07. Marks: 1]

19.6

What is DDoS? Differentiate between Direct DDoS attack and Reflector DDoS attack. [2007.
Marks: 1 + 2]

19.7

What is Digital Immune System? Clearly describe the typical steps of Digital Immune
System operation. [2007. Marks: 1 + 4]

19.8

What is the difference between rule-based intrusion detection and statistical anomaly
detection? [2008. Marks: 2]

CHAPTER 30 (FOROUZAN), CHAPTERS 3, 5 (STALLINGS)CRYPTOGRAPHY, AES, DES
30.1

Explain the steps for generating keys for RSA algorithm, and generate any key-pair using
the primes 3 and 11. [2006. Marks: 2 + 2]

30.2

What is the basic purpose of Diffie-Hellman algorithm? Using this algorithm, how can Evefool two communicating partners Alice and Bob by creating two keys: one between Alice andherself, and another between herself and Bob? [2006. Marks: 1 + 5]

30.3

Compare / Distinguish between DES and AES. [2006. Marks: 2]

30.4

Explain generation technique of round keys for AES. [In-course 08-09. Marks: 3]

30.5

Illustrate the general structure of the 10-round AES and draw a flowchart showing theoperations of each round. [In-course 06-07. Marks: 2]
ALSO, Clearly state the operations of any round. [In-course 05-06. Marks: 3]
ALSO, Name different stages in a common round of AES and clearly explain the operationof any one round. [In-course 08-09. Marks: 1 + 4]
ALSO, Explain the encryption process of AES for any one key-size and list the operations ofits common round. [2006. Marks: 4]

30.6

Distinguish between Cipher Feedback Mode and Output Feedback Mode. [In-course 06-07.
Marks: 3]
ALSO, Clearly explain any one of them. [In-course 05-06. Marks: 3]

30.7

Illustrate one round of DES encryption and (using a flowchart) explain DES function. [Incourse 06-07, 05-06. Marks: 2 + 3]
ALSO, Illustrate the internal blocks of operations of one round of DES and explain theinternal operations of DES function. [In-course 08-09. Marks: 2 + 3]

30.8

What is the major advantage of public key cryptography over symmetric key cryptography?
[2008. Marks: 1]2

CHAPTER 31 (FOROUZAN)NETWORK SECURITY
31.1

What do you understand by message non-repudiation? Explain the role of a trusted center
for message non-repudiation. [2006. Marks: 1 + 3]

31.2

Illustrate the process of creation and verification of message authentication code. [2006.
Marks: 2]

31.3

What is digital signature? Explain the uses of hash functions for generating and verifying
digital signature. [2006. Marks: 1 + 4]

31.4

Discuss the relationship between digital signature, digital certificate authority and public
key infrastructure. [2006. Marks: 5]

31.5

Can you use a secret (symmetric) key to both sign and verify a digital signature? Justify
your answer. [2007. Marks: 3]

31.6

In Kerberos Protocol, what are the steps that Alice (user requesting service) should follow
to communicate/receive services from three different servers: Bob, Eve and Trudy? [2007.
Marks: 5]

31.7

What purpose does the authenticator in a Kerberos message serve? Detail one flaw Merritt
and Bellovin identified in its design. [2008. Marks: 1 + 2]

31.8

How does digital signature provide message non-repudiation? [2008, 2007. Marks: 3]

31.9

What is digital signature? State the requirements for digital signature. [2008, 2007. Marks:5]

31.10

What are the threats with direct digital signature scheme? [2008. Marks: 1]

31.11

Clearly describe the steps for generating any one RSA key-pair using the prime numbers 5and 11. [In-course 06-07. Marks: 3]

31.12

Suppose Bob chooses two prime numbers 7 and 11. How can he determine the RSA keys?
Show the procedure and determine a key pair. [In-course 05-06. Marks: 3 + 2]

31.13

Distinguish between message authentication code and message digest. [In-course 06-07.
Marks: 2]

31.14

Explain how a digital signature provides message integrity and message authentication
services. [In-course 08-09, 06-07. Marks: 3]

31.15How can a session key be created between Alice and Bob using any method? [In-course 0607. Marks: 2]

31.16

Explain the uses of different Kerberos servers. [In-course 06-07. Marks: 3]
ALSO, Using an illustration, explain the purpose of authentication server and ticket
granting server of Kerberos version 4. [In-course 08-09. Marks: 3]

31.17

31.18

Distinguish between message authentication and entity authentication. Explain entity
authentication using symmetric key cipher or asymmetric key cipher. [In-course 05-06. Marks:2 + 3]What do you understand by a trusted center? [In-course 05-06. Marks: 1]

31.19

Distinguish between modification detection code and message authentication code. [Incourse 08-09. Marks: 2]

31.20

Using an illustration explain the principle of operation of SHA-1 or any other hashalgorithm. [In-course 08-09. Marks: 3]

3

ALSO, How does SHA-1 create message digest? [2007. Marks: 3]
31.21

What do you understand by challenge-response method of entity authentication? Using anillustration, explain any one such method for entity authentication. [In-course 08-09. Marks: 1+ 2]

31.22

What is the purpose of a digital certificate? List at least five fields of a digital certificate
using X.509 standard. [In-course 08-09. Marks: 2]

31.23

List possible attacks on fixed passwords and explain salting a password. [2006. Marks: 1 +3]
ALSO, Explain dictionary attack on fixed passwords. [In-course 08-09. Marks: 2]
ALSO, How can a system prevent a guessing attack on a fixed password? [2007. Marks: 1]
ALSO, How does salted password make dictionary attack more difficult? [2007, In-course
08-09. Marks: 2]

31.24

What is Hash function? Mention the requirements for hash function. [2008. Marks: 5]

31.25

Briefly explain MD5 hash algorithm. [2008. Marks: 5]

31.26

In what order should the signature function and the confidentiality function be applied to amessage and why? [2008. Marks: 2]

4

CHAPTER 32 (FOROUZAN)SECURITY IN THE INTERNET
32.1

How does ESP of IPSec provide source authentication, data integrity and privacy services
for communication between two users? [2006. Marks: 6]

32.2

How does IPSec provide source authentication and data integrity for communication
between two users? [2007. Marks: 5]

32.3

What is a virtual private network? How can IPSec in the tunnel mode provide
authentication, integrity and privacy services for a virtual private network? [2006. Marks: 1 +3]

32.4

What are the techniques to achieve secure email transactions along with sender’s identity?
[2006. Marks: 5]

32.5

Differentiate between Transport mode and Tunnel mode of IPSec Protocol. [2007. Marks:2]

32.6

Differentiate between Authentication Header Protocol and Encapsulating Security Payload
Protocol in IPSec. [In-course 06-07. Marks: 3]
ALSO, Differentiate between authentication data of AH and ESP of IPSec. [In-course 0809. Marks: 2]

32.7

What is the purpose of firewall? Differentiate between packet filter and proxy firewall.
[2007. Marks: 1 + 3]

32.8

What is R64 conversion? Why is R64 conversion useful for an email application? [2008.
Marks: 1 + 1]

32.9

How does PGP use the concept of trust? [2008. Marks: 2]

32.10

What services are provided by SSL record protocol? [2008. Marks: 2]

32.11State any four services of SSL. [In-course 06-07. Marks: 2]

32.12

What is dual signature and what is its purpose? [2008. Marks: 1 + 1]

32.13

What is the purpose of Proxy Firewall? [In-course 06-07. Marks: 1]

32.14

What is VPN? Why is it needed? [In-course 06-07. Marks: 1 + 1]

32.15

What is the purpose of Handshake protocol in SSL? [In-course 06-07. Marks: 1]

32.16

How does SSL create Cryptographic Secret? [In-course 06-07. Marks: 2]

32.17

Explain the operation of any one of the following: [In-course 08-09. Marks: 3]i.
Authentication Header Protocol of IPSec in transport mode.
ii.
Encapsulating Security Protocol of IPSec in transport mode.

32.18
32.19

32.20
32.21
32.22
32.23

Point out the security services required when a customer shops online using WWW. [Incourse 08-09. Marks: 2]
Explain any one of the following: [In-course 08-09. Marks: 3]i.
Security association of IPSecii.
Security parameters of SSL
Using an appropriate illustration, explain how authentication and confidentiality services
are provided by PGP for secure email. [In-course 08-09. Marks: 5]
What is Hybrid Network? Why is it needed? [2007. Marks: 1 + 1]
Why should you include a message authentication code (MAC) with a message? What is thedifference between a MAC and an HMAC? [2008. Marks: 1 + 1]
Explain Hand-Shake protocol for web security approaches. [2008. Marks: 4]
5