Mảnh bí kíp CRY302

21. Verifying that users are who they say they are and that each input arriving at the system came from a trusted source is _________ . A) authenticity B) credibility C) accountability D) Integrity

A

22. A __________ is any action that compromises the security of information owned by an organization. A) security attack B) security service C) security alert D) security mechanism

A

27. A(n) __________ is a potential for violation of security, which exists when there is a circumstance, capability, action or event that could breach security and cause harm. A) threat B) attack C) risk D) attack vector

A

3. Authentication protocols and encryption algorithms are examples of security mechanisms. A) True B) False

A

30. Symmetric encryption remains by far the most widely used of the two types of encryption. A) True B) False

A

97. An area of ongoing research is the development of efficient algorithms for determining if a randomly chosen large integer is a prime number. A) True B) False

A

99. The number 37 is prime so therefore all of the positive integers from 1 to 36 are relatively prime to 37. A) True B) False

A

the multiplication operation is associative and is distributive over the addition operation. A) True B) False

A

16. __________ is the most common method used to conceal small blocks of data, such as encryption keys and hash function values, which are used in digital signatures.

A) Symmetric encryption B) Data integrity algorithms C) Asymmetric encryption D) Authentication protocols C

66. The vast majority of network-based symmetric cryptographic applications make use of ________ ciphers.

A) linear B) block C) permutation D) Stream B

108. A public-key encryption scheme is not vulnerable to a brute-force attack. A) True B) False

B

110. Timing attacks are ciphertext attacks that are only applicable to RSA. A) True B) False

B

112. The Playfair algorithm encrypts three letters at a time. A) True B) False

B

20. A loss of __________ is the unauthorized disclosure of information. A) authenticity B) confidentiality C) reliability D) Integrity

B

122. In AES, how many bytes in State are affected by ShiftRows? A) 4 B) 8 C) 12 D) 14 E) None of the responses above is correct.

C

80. A _________ is a field with a finite number of elements. A) finite group B) finite order C) finite field D) finite ring

C

1. The OSI security architecture provides a systematic framework for defining security attacks, mechanisms, and services. A) True B) False

A

100. The Miller-Rabin test can determine if a number is not prime but cannot determine if a number is prime. A) True B) False

A

107. A trap-door one-way function is easy to calculate in one direction and infeasible to calculate in the other direction unless certain additional information is known. A) True B) False

A

109. Before the application of the public-key cryptosystem each participant must generate a pair of keys. A) True B) False

A

11. The connection-oriented integrity service addresses both message stream modification and denial of service. A) True B) False

A

111. The Playfair algorithm is based on the use of a 5 × 5 matrix of letters constructed using a keyword. A) True B) False

A

115. A group is a set of elements that is closed under a binary operation and that is associative and that includes an identity element and an inverse element. A) True B) False

A

117. A field is a ring in which the multiplication operation is commutative, has no zero divisors, and includes an identity element and an inverse element. A) True B) False

A

12. All the techniques for providing security have two components: a security- related transformation on the information to be sent and some secret information shared by the two principals. A) True B) False

A

121. Within GF(2n), a polynomial m(x) is called irreducible if and only if it cannot be expressed a product of two polynomials, both of degree lower than that of m(x). A) True B) False

A

123. The ___________ allows for block lengths of 128, 192 or 256 bits. A) Rijndael cipher B) DES algorithm C) AES algorithm D) All of these responses are correct.

A

13. Information access threats intercept or modify data on behalf of users who should not have access to that data. A) True B) False

A

15. Symmetric encryption is used to conceal the contents of blocks or streams of data of any size, including messages, files, encryption keys, and passwords. A) True B) False

A

19. The three concepts that form what is often referred to as the CIA triad are ________ . These three concepts embody the fundamental security objectives for both data and for information and computing services. A) confidentiality, integrity and availability B) communication, integrity and authentication C) confidentiality, integrity, access control D) communication, information and authenticity

A

31. Rotor machines are sophisticated precomputer hardware devices that use substitution techniques. A) True B) False

A

33. With the use of symmetric encryption, the principal security problem is maintaining the secrecy of the key. A) True B) False

A

35. The encryption/decryption algorithm will produce a different output depending on the specific secret key being used at the time. The exact substitutions and transformations performed by the algorithm depend on the key. A) True B) False

A

37. On average, half of all possible keys must be tried to achieve success with a brute-force attack. A) True B) False

A

39. Monoalphabetic ciphers are easy to break because they reflect the frequency data of the original alphabet. A) True B) False

A

4. The more critical a component or service, the higher the level of required availability. A) True B) False

A

40. As with Playfair, the strength of the Hill cipher is that it completely hides single letter frequencies. A) True B) False

A

43. The most widely used cipher is the Data Encryption Standard. A) True B) False

A

47. A __________ attack involves trying every possible key until an intelligible translation of the ciphertext is obtained. A) brute-force B) Caesar attack C) ciphertext only D) chosen plaintext

A

50. The __________ attack is the easiest to defend against because the opponent has the least amount of information to work with. A) ciphertext-only B) chosen ciphertext C) known plaintext D) chosen plaintext

A

53. A technique referred to as a __________ is a mapping achieved by performing some sort of permutation on the plaintext letters. A) transposition cipher B) polyalphabetic cipher C) Caesar cipher D) monoalphabetic cipher

A

54. The methods of __________ conceal the existence of the message in a graphic image. A) steganography B) decryptology C) cryptology D) Cryptography

A

56. The Feistel cipher structure, based on Shannon's proposal of 1945, dates back over a quarter of a century and is the structure used by many significant symmetric block ciphers currently in use. A) True B) False

A

6. The field of network and Internet security consists of measures to deter, prevent, detect and correct security violations that involve the transmission of information. A) True B) False

A

60. Greater complexity in the subkey generation algorithm should lead to greater difficulty of cryptanalysis. A) True B) False

A

61. A prime concern with DES has been its vulnerability to brute-force attack because of its relatively short key length. A) True B) False

A

63. DES exhibits the classic __________ block cipher structure, which consists of a number of identical rounds of processing. A) Feistel B) SAC C) Shannon D) Rendell

A

64. A sequence of plaintext elements is replaced by a __________ of that sequence which means that no elements are added, deleted or replaced in the sequence, but rather the order in which the elements appear in the sequence is changed. A) permutation B) diffusion C) stream D) Substitution

A

68. Finite fields play a crucial role in several areas of cryptography. A) True B) False

A

7. Patient allergy information is an example of an asset with a high requirement for integrity. A) True B) False

A

70. Two integers a and b are said to be congruent modulo n, if (a mod n) = (b mod n). A) True B) False

A

71. Finite fields of order p can be defined using arithmetic mod p. A) True B) False

A

73. The rules for ordinary arithmetic involving addition, subtraction, and multiplication carry over into modular arithmetic. A) True B) False

A

74. A field is a set in which we can do addition, subtraction, multiplication and division without leaving the set. A) True B) False

A

76. Polynomial arithmetic includes the operations of addition, subtraction and multiplication. A) True B) False

A

77. Two integers are __________ if their only common positive integer factor is 1. A) relatively prime B) congruent modulo C) polynomials D) Residual

A

78. The __________ of two numbers is the largest integer that divides both numbers. A) greatest common divisor B) prime polynomial C) lowest common divisor D) integral divisor

A

81. The principle requirement of random or pseudorandom number generation is that the generated number stream be unpredictable. A) True B) False

A

84. With true random sequences each number is statistically independent of other numbers in the sequence and therefore unpredictable. A) True B) False

A

85. The true random number generator may simply involve conversion of an analog source to a binary output. A) True B) False

A

87. If the PRF does not generate effectively random 128-bit output values it may be possible for an adversary to narrow the possibilities and successfully use a brute force attack. A) True B) False

A

88. The seed that serves as input to the PRNG must be secure for cryptographic applications. A) True B) False

A

89. Three broad categories of cryptographic algorithms are commonly used to create PRNGs: symmetric block ciphers, asymmetric ciphers, and hash functions and message authentication codes. A) True B) False

A

9. Data origin authentication does not provide protection against the modification of data units. A) True B) False

A

91. A __________ is used to produce a pseudorandom string of bits of some fixed length. A) PRF B) PRNG C) OFB PRNG D) TRNG

A

93. The best that can be done to determine if a PRNG generates numbers that have the characteristic of randomness is on the basis of multiple tests. These tests should seek to establish uniformity, scalability, and __________ . A) consistency B) authentication C) frequency D) Sequencing

A

94. The __________ test is the most basic test of randomness and must be included in any test suite. A) frequency B) runs C) unpredictability D) Maurer

A

95. One of the useful features of the Chinese remainder theorem is that it provides a way to manipulate potentially very large numbers mod M in terms of tuples of smaller numbers. A) True B) False

A

10. The emphasis in dealing with active attacks is on prevention rather than detection. A) True B) False

B

102. Discrete logarithms are fundamental to the ____________ . A) Euler algorithm B) digital signature algorithm C) Miller-Rabin algorithm D) Rijndael algorithm

B

104. Asymmetric encryption can be used for confidentiality but not for authentication. A) True B) False

B

105. Public-key encryption is more secure from cryptanalysis than symmetric encryption. A) True B) False

B

118. The multiplicative inverse of 3, modulo 5, is __________ . A) 1 B) 2 C) 3 D) 4 E) None of the responses above is correct.

B

119. The additive inverse of 3, modulo 5, is __________ . A) 1 B) 2 C) 3 D) 4 E) None of the responses above is correct.

B

125. A time-varying value that has at most a negligible chance of repeating is called a ___________ . A) temporal key B) nonce C) cipher D) None of these responses is correct.

B

126. The minimum number of distinct keys used in triple encryption is ___________ . A) 1 B) 2 C) 3 D) None of these responses is correct.

B

128. A group G is said to be _________ if it satisfies the condition a*b = b*a for all a,b in G. A) abelian B) commutative C) cyclic D) Infinite

B

14. The data integrity service inserts bits into gaps in a data stream to frustrate traffic analysis attempts. A) True B) False

B

17. A common technique for masking contents of messages or other information traffic so that opponents can not extract the information from the message is __________ . A) integrity B) encryption C) analysis D) Masquerade

B

18. __________ involves the passive capture of a data unit and its subsequent retransmission to produce an unauthorized effect. A) Disruption B) Replay C) Service denial D) Masquerade

B

2. Security attacks are classified as either passive or aggressive. A) True B) False

B

23. A __________ takes place when one entity pretends to be a different entity. A) replay B) masquerade C) service denial D) passive attack

B

25. A(n) __________ service is one that protects a system to ensure its availability and addresses the security concerns raised by denial- of- service attacks. A) replay B) availability C) masquerade D) Integrity

B

29. Data appended to, or a cryptographic transformation of, a data unit that allows a recipient of the data unit to prove the source and integrity of the data unit and protect against forgery is a(n) ___________ . A) security audit trail B) digital signature C) encipherment D) authentication exchange

B

32. Symmetric encryption is a form of cryptosystem in which encryption and decryption are performed using different keys. It is also known as non-conventional encryption. A) True B) False

B

34. The process of converting from plaintext to ciphertext is known as deciphering or decryption. A) True B) False

B

36. When using symmetric encryption it is very important to keep the algorithm secret. A) True B) False

B

38. Ciphertext generated using a computationally secure encryption scheme is impossible for an opponent to decrypt simply because the required information is not there. A) True B) False

B

42. The one-time pad has unlimited utility and is useful primarily for high-bandwidth channels requiring low security. A) True B) False

B

44. Steganography renders the message unintelligible to outsiders by various transformations of the text. A) True B) False

B

45. __________ techniques map plaintext elements (characters, bits) into ciphertext elements. A) Transposition B) Substitution C) Traditional D) Symmetric

B

114. The avalanche effect is a property of any encryption algorithm such that a small change in ___________ produces a significant change in the ciphertext. A) the plaintext B) the key C) Both A and B responses are correct. D) None of the responses above are correct.

C

127. If r and n are relatively prime integers with n > 0. and if φ(n) is the least positive exponent m such that am ≡ 1 mod n, then r is called a _________ modulo n. A) simple factor B) relative prime C) primitive root D) None of these responses is correct.

C

28. The protection of the information that might be derived from observation of traffic flows is _________ . A) connectionless confidentiality B) connection confidentiality C) traffic- flow confidentiality D) selective- field confidentiality

C

48. Techniques used for deciphering a message without any knowledge of the enciphering details is ___________ . A) blind deciphering B) steganography C) cryptanalysis D) Transposition

C

51. _________ refer(s) to common two-letter combinations in the English language. A) Streaming B) Transposition C) Digrams D) Polyalphabetic cipher

C

52. A way to improve on the simple monoalphabetic technique is to use different monoalphabetic substitutions as one proceeds through the plaintext message. The general name for this approach is ___________ . A) rail fence cipher B) cryptanalysis C) polyalphabetic substitution cipher D) polyanalysis cipher

C

90. A secret key for symmetric encryption that is generated for use for a short period of time is called a _________ . A) strategic key B) sequence key C) session key D) stream key

C

________ and ________ . A) Shift rows and Mix columns B) Mix rows and Shift columns C) Shift rows, Mix columns and Add round key D) Shift rows, Mix columns and Expand key E) None of the responses above is correct.

C

46. Joseph Mauborgne proposed an improvement to the Vernam cipher that uses a random key that is as long as the message so that the key does not need to be repeated. The key is used to encrypt and decrypt a single message and then is discarded. Each new message requires a new key of the same length as the new message. This scheme is known as a(n) __________ . A) pascaline B) one-time pad C) polycipher D) Enigma

B

49. __________ attacks exploit the characteristics of the algorithm to attempt to deduce a specific plaintext or to deduce the key being used. A) Brute-force B) Cryptanalytic C) Block cipher D) Transposition

B

5. Security services include access control, data confidentiality and data integrity, but do not include authentication. A) True B) False

B

55. The vast majority of network based symmetric cryptographic applications make use of stream ciphers. A) True B) False

B

57. DES uses a 56-bit block and a 64-bit key. A) True B) False

B

57. DES uses a 64-bit block and a 56-bit key. A) True B) False

B

58. Confusion seeks to make the statistical relationship between the plaintext and ciphertext as complex as possible in order to thwart attempts to deduce the key. A) True B) False

B

59. All other things being equal, smaller block sizes mean greater security. A) True B) False

B

62. The strict avalanche criterion and the bit independence criterion appear to weaken the effectiveness of the confusion function. A) True B) False

B

69. Unlike ordinary addition, there is not an additive inverse to each integer in modular arithmetic. A) True B) False

B

72. The Advanced Encryption Standard uses infinite fields. A) True B) False

B

75. It is easy to find the multiplicative inverse of an element in g(p) for large values of p by constructing a multiplication table, however for small values of p this approach is not practical. A) True B) False

B

8. The OSI security architecture was not developed as an international standard, therefore causing an obstacle for computer and communication vendors when developing security features. A) True B) False

B

83. There are well-defined tests for determining uniform distribution and independence to validate that a sequence of numbers is random. A) True B) False

B

86. Examples of a pseudorandom function are decryption keys and nonces. A) True B) False

B

92. A source that is effectively random is referred to as a(n) __________ . A) open source B) entropy source C) keystream D) Seed

B

96. All integers have primitive roots. A) True B) False

B

98. Discrete logarithms are not fundamental to public-key algorithms. A) True B) False

B

101. An important quantity in number theory referred to as __________ , is defined as the number of positive integers less than n and relatively prime to n. A) CRT B) Miller-Rabin C) Euler's totient function D) Fermat's theorem

C

103. Discrete logarithms are fundamental to a number of public-key algorithms including __________ key exchange and the DSA. A) Rijndael-Fadiman B) Miller-Rabin C) Diffie-Hellman D) Fermat-Euler

C

113. An encryption scheme is said to be computationally secure if __________ . A) the cost of breaking the cipher exceeds the value of the encrypted information B) the time required to break the cipher exceeds the useful lifetime of the information C) the amount of time required to break the cipher is greater than the fastest CPUs D) Both A and B responses are correct.

D

124. To apply a block cipher in a variety of applications, five modes of operation have been defined by NIST, including modes _________ . A) DES and AES B) CBC and CTR C) ECB and OFB D) Both B and C responses are correct.

D

24. __________ is the protection of transmitted data from passive attacks. A) Access control B) Data control C) Nonrepudiation D) Confidentiality

D

26. __________ threats exploit service flaws in computers to inhibit use by legitimate users. A) Information access B) Reliability C) Passive D) Service

D

65. A __________ cipher is one that encrypts a digital data stream one bit or one byte at a time. A) product B) block C) key D) Stream

D

67. The greater the number of rounds, the __________ it is to perform cryptanalysis. A) easier B) less difficult C) equally difficult D) Harder

D

79. A _________ is a set of elements on which two arithmetic operations have been defined and which has the properties of ordinary arithmetic, such as closure, associativity, commutativity, distributivity, and having both additive and multiplicative inverses. A) modulus B) ring C) group D) Field

D