Cryptography

Trojan Horse

31. Decipher the message IAIWWT using the Hill cipher with the inverse key .

ONALLY

32.Decipher the message YITJPG using the Hill cipher with the inverse key
Take the indices of letters according to the given table.

DIFFIC

33.A form of cryptosystem in which encryption and decryption are performed using the same key. Also known as conventional encryption.

Symmetric encryption

34.______________ is the science and art of transforming messages to make them secure and immune to attacks.

Cryptography

35.Decipher the ciphertext QMHXIVQ using Caesar Cipher with the key=4.
MIDTERM

36.Encrypt the message "HELLO" using the Hill cipher with the key Take the indices of letters according to the given table.

BLNCKX

38.Encrypt the message WELCOME! using Caesar Cipher with the key = 5.

BJQHTRJ!

39.Encrypt the message WELCOME! using Caesar Cipher with the key = 34

EMTKWUM!

40.Embedded in a computer program that checks for a certain set of conditions to be present on the system. When these conditions are met, it executes some function resulting in unauthorized actions.

Logic Bomb

41.Find d using the RSA algorithm, if p = 3; q = 11, e = 7; M = 5.

42.Find d using the RSA algorithm, if p = 5; q = 11, e = 3; M = 9.

43.Free from mistake or error and having the value that the end-user expects.

Accuracy

44.How does the Social Engineering work?

People write passwords in different places and disclose passwords naively to others

45.How does the Dictionary attack work?

Hacker tries all words in dictionary to crack password

46.How does the Dumpster Diving work?

People dump their trash papers in garbage which may contain information to crack passwords

47.How does the Brute Force attack work?

Try all permutations of the letters and symbols in the alphabet

48.How can we protect the system?

Setup IDS

Encrypt important data

Setup firewall

49.If a key is 8 bits long, how many possible numbers that the key can generate?

Ответ: 256

50If a wrong key is entered to decrypt a message, what will happen?

The output will be gibberish

51.If the encrypted message is XBPG and deciphered text is QUIZ using Caesar Cipher, what is the value of key?

52.DMZ What is one advantage of setting up a DMZ with two firewalls?

You can control where traffic goes in the three networks

53.In an RSA system, the public key of a given user is e = 31, n = 3599. What is the value of p and q?

p = 61, q = 59

54.In an RSA system, the public key of a given user is e = 31, n = 3599. What is the φ(n)?

φ(n) = 3480

55.In a public-key system using RSA, you intercept the ciphertext C = 10 sent to a user whose public key is e = 5, n = 35. What is the value of p and q?

p=5, q=7

56.In a public-key system using RSA, you intercept the ciphertext C = 10 sent to a user whose public key is e = 5, n = 35. What is the plaintext M?

57.In a public-key system using RSA, you intercept the plaintext M = 13 sent to a user whose public key is e = 5, n = 35. What will be the ciphertext C?

58.In a public-key system using RSA, you intercept the plaintext M = 25 sent to a user whose public key is e = 5, n = 35. What will be the ciphertext C?

59.In a public-key system using RSA, you intercept the ciphertext C = 10 sent to a user whose public key is e = 5, n = 35. What is the value of p and q?

q=7, p = 5

60.In a public-key system using RSA, you intercept the ciphertext C = 10 sent to a user whose public key is e = 5, n = 35. What is the φ ?

61.In a public-key system using RSA, you intercept the ciphertext C = 10 sent to a user whose public key is e = 5, n = 35. What is the value of d?

62.Malicious attempts by a single person or a group of people to cause the victim, site, or node to deny service to its customers

Denial of Service Attack

63.Match each term according to their meanings in Public-Key Cryptosystem

Ciphertext: this is the scrambled message produced as output
Encryption algorithm: the algorithm performs various transformations on the plaintext
Decryption algorithm: this algorithms accepts the ciphertext and the matching key and produces the original plaintext
Plaintext: this is the readable message or data that is fed into algorithm as the input
Public and private keys: this is the pair of keys

64.Weaknesses of a system that could be accidentally or intentionally exploited to damage assets.

Vulnerability

65.One objective of cryptography is keeping information secret from all but those who are authorised to see it. The term referring to this is:

Confidentiality

66.One objective of cryptography is property of being accessible and useable upon demand by an authorized entity.

Availability

67.One objective of cryptography is conveyance, to another entity, of official sanction to do or be something. The term referring to this is:

Authorisation

68One objective of cryptography is ensuring information has not been altered by unauthorised or unknown means. The term referring to this is:

Data integrity

69.One objective of cryptography is identifying and acknowledging the identity of entity. The term referring to this is:

Identification

70.One objective of cryptography is prevention of authorized access to resources or the delaying of time-critical operations.

Denial of service

71.One of the two keys used in an asymmetric encryption system. For secure communication, the ___________ should only be known to its creator.

private key

72.One of the two keys used in an asymmetric encryption system. The ____key is made ________, to be used in conjunction with a corresponding ______________key

Public, public, private

73.One of the most famous documented DDoS attacks Back. How does the Back work?

Attack is launched against an apache Web server, which is flooded with requests containing a large number of front-slash (/) characters in the URL.

74.One of the most famous documented DDoS attacks Mailbomb. How does the Mailbomb work?

The victim's mail queue is flooded by an abundance of messages, causing system failure.

75.One of the most famous documented DDoS attacks Land. How does the Land work?

The attacker sends the victim a TCP SYN packet that contains the same IP address as the source and destination addresses. Such a packet completely locks the victim's system

76.One of the most famous documented DDoS attacks CrashIIS. How does the CrashIIS work?

The attacker sends the victim a malformed GET request, which can crash the Web server

76.One of the most famous documented DDoS attacks Apache2. How does the Apache2work?

The client asks for a service by sending a request with many HTTP headers resulting Apache Web server to crash

77.Perform encryption using the RSA algorithm, if p = 3; q = 11, e = 7; M = 5.

78.Perform decryption using the RSA algorithm, if p = 5; q = 11, e = 3; C = 14.

79.Provides a user with protection against discovery and misuse of his or her identity by other users.

Privacy

80.Program that can replicate itself and send copies from computer to computer across network connections. Usually performs some unwanted function.

Worm

81.Program that consumes system resources by replicating itself.

Bacteria

82.Possibility of an incident or attack to cause damage to your enterprise

Risk

83.Set of hacker tools used after attacker has broken into a computer system and gained root-level access.

Rootkits

84.Secret undocumented entry point into a program, used to grant access without normal methods of access authentication.

Trapdoor

85.The translation of encrypted text or data (called ciphertext) into original text or data (called plaintext). Also called deciphering.

Decryption

86.The key used in a symmetric encryption system. Both participants must share the same key, and this key must remain secret to protect the communication.

Secret key

87.The quality or state of being genuine or original, rather than a reproduction or fabrication.

Authenticity

88.The quality or state of having ownership or control of some object or item.

Possession

89.The process of verifying and identity claimed by or for a system entity.

Authentication

90.The Vigenere cipher is which of the following types:

Polyaplhabetic

91.The Caesar cipher is a __________ cipher that has a key of 3.

Shift

92.The best-known multiple-letter encryption cipher, which treats digrams in the plaintext as single units and translates these units into ciphertext digrams

Playfair cipher

93.The word "asymmetric" in public-key cryptography means:

The key to encrypt is different from the key to decrypt

94.The_______________ is a widely used cryptographic hash function that produces a 128 –bit (16byte) hash value

MD5 Message Digest alghorithm

95.The _______________ is a number or a set of numbers on which the cipher operates.

Key

96.Use the Playfair cipher with the keyword "PLAYFAIR" to decrypt the message "YPYQ".

AFAS

96.Use the Playfair cipher with the keyword "PLAYFAIR" to encrypt the message "GOTO".

OVNQ

97.Using this Playfair matrix decipher the message: UZTB

MUST

98.A process of identifying, analyzing and controlling critical information.

OPSEC

99.Which of the following statements is the definition of IP Spoofing - Source Routing?

Attacker spoofs the IP address of another machine and inserts itself between the attacked machine and the spoofed machine to intercept replies.

100.Using this Playfair matrix encrypt the message: Cadogans

TG TU ER VF

101.Using Magic square cipher decipher the message “..S….NS…IE…O.S..” with the key 5 and generated magic square

SEESSION

102.Using Magic square cipher encrypt the message “MAJOR” with the given key 3

.M..RJA.O

104.Using Feistel Cipher some information was encrypted, as the ciphertext scrambled message with the length 4n bits was outputted. What is the bit length of initial plaintext?

105.Weakness of a system that could be accidentally or intentionally exploited to damage assets

Vulnerabilities

106.What is Encryption algorithm?

Performs various substitutions and transformations on the plaintext

107.What is Data integrity?

Ensuring information has not be altered

108.What is Decryption algorithm?

takes the ciphertext and the secret key and produces the original plaintext

109.What is Hacking?

Hacking refers to an array of activities which are done to intrude some one else's personal information space so as to use for malicious, unwanted purposes

110.What is Cracking?

All of the statements

111.What is Phreaking?

Phreaking is basically hacking with a telephone. Using different "boxes" and "tricks" to manipulate the phone companies and their phones, you gain many things.

112.What is plaintext?

The original intelligible message or data that is fed into the algorithm as input

113.What does a firewall do?

Protects your computer from Internet intrusion

114.What should do after hacked?

All of the statements

115.What will be the value of key in Caser Cipher if initially key=65?

116.Which attack takes advantage of the way in which information is stored by computer programs?

Buffer overflow attacks

117.Which one of the statement is a formula to find cipher in RSA?

c = m^e (mod n).

118.Which one of the statement is a formula to find plain in RSA?