EC-COUNCIL 212-81 Online Practice Questions and Exam Preparation

EC-COUNCIL 212-81 Online Questions & Answers

• Question 11:

  A measure of the uncertainty associated with a random variable.

  A. Collision
  B. Whitening
  C. Diffusion
  D. Entropy
  D. Entropy

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  Explanation

  Entropy https://en.wikipedia.org/wiki/Entropy_(information_theory) In information theory, the entropy of a random variable is the average level of "information", "surprise", or "uncertainty" inherent in the variable's possible outcomes. The concept of information entropy was introduced by Claude Shannon in his 1948 paper "A Mathematical Theory of Communication".

• Question 12:

  The time and effort required to break a security measure.

  A. Session Key
  B. Work factor
  C. Non-repudiation
  D. Payload
  B. Work factor

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  Explanation

  Work factor

  Work factor - the time and effort required to break a security measure.

• Question 13:

  What is a salt?

  A. Key whitening
  B. Random bits intermixed with a symmetric cipher to increase randomness and make it more secure
  C. Key rotation
  D. Random bits intermixed with a hash to increase randomness and reduce collisions
  D. Random bits intermixed with a hash to increase randomness and reduce collisions

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  Explanation

  Random bits intermixed with a hash to increase randomness and reduce collisions https://en.wikipedia.org/wiki/Salt_(cryptography)

  Salt is random data that is used as an additional input to a one-way function that hashes data, a password or passphrase. Salts are used to safeguard passwords in storage. Historically a password was stored in plaintext on a system, but

  over time additional safeguards were developed to protect a user's password against being read from the system. A salt is one of those methods.

• Question 14:

  You are trying to find a modern method for security web traffic for use in your company's ecommerce web site. Which one of the following is used to encrypt web pages and uses bilateral authentication?

  A. AES
  B. SSL
  C. TLS
  D. 3DES
  C. TLS

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  Explanation

  TLS https://en.wikipedia.org/wiki/Mutual_authentication Mutual authentication or two-way authentication refers to two parties authenticating each other at the same time, being a default mode of authentication in some protocols (IKE, SSH) and optional in others (TLS). By default the TLS protocol only proves the identity of the server to the client using X.509 certificate and the authentication of the client to the server is left to the application layer. TLS also offers client-to-server authentication using client-side

  X.509 authentication. As it requires provisioning of the certificates to the clients and involves less user-friendly experience, it's rarely used in end-user applications.

• Question 15:

  If you use substitution alone, what weakness is present in the resulting cipher text?

  A. It is the same length as the original text
  B. It is easily broken with modern computers
  C. It maintains letter and word frequency
  D. It is too simple
  C. It maintains letter and word frequency

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  Explanation

  It maintains letter and word frequency https://en.wikipedia.org/wiki/Frequency_analysis Frequency analysis (also known as counting letters) is the study of the frequency of letters or groups of letters in a ciphertext. The method is used as an aid to breaking classical ciphers. Frequency analysis is based on the fact that, in any given stretch of written language, certain letters and combinations of letters occur with varying frequencies. Moreover, there is a characteristic distribution of letters that is roughly the same for almost all samples of that language. For instance, given a section of English language, E, T, A and O are the most common, while Z, Q, X and J are rare. Likewise, TH, ER, ON, and AN are the most common pairs of letters (termed bigrams or digraphs), and SS, EE, TT, and FF are the most common repeats. The nonsense phrase "ETAOIN SHRDLU" represents the 12 most frequent letters in typical English language text. In some ciphers, such properties of the natural language plaintext are preserved in the ciphertext, and these patterns have the potential to be exploited in a ciphertext-only attack.

• Question 16:

  Fred is using an operating system that stores all passwords as an MD5 hash. What size is an MD5 message digest (hash)?

  A. 160
  B. 512
  C. 256
  D. 128
  D. 128

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  Explanation

  https://en.wikipedia.org/wiki/MD5

  The MD5 message-digest algorithm is a widely used hash function producing a 128-bit hash value.

• Question 17:

  Which of the following algorithms uses three different keys to encrypt the plain text?

  A. Skipjack
  B. AES
  C. Blowfish
  D. 3DES
  D. 3DES

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  Explanation

  3DES https://en.wikipedia.org/wiki/Triple_DES Triple DES (3DES) has a three different keys with same size (56-bit).

• Question 18:

  John is trying to select the appropriate authentication protocol for his company. Which of the following types of authentication solutions use tickets to provide access to various resources from a central location?

  A. Kerberos
  B. EAP
  C. Radius
  D. CHAP
  A. Kerberos

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  Explanation

• Question 19:

  In order to understand RSA. you must understand the key generation algorithm as well as the encryption and decryption algorithms. Which one of the following equations describes the encryption process for RSA?

  A. Me mod n
  B. Ce mod n
  C. y2 = x3 + Ax + B
  D. P = Cd mod n
  B. Ce mod n

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  Explanation

• Question 20:

  A _______ product refers to an NSA-endorsed classified or controlled cryptographic item for classified or sensitive U. S. government information, including cryptographic equipment, assembly, or component classified or certified by NSA for encrypting and decrypting classified and sensitive national security information when appropriately keyed

  A. 1
  B. 4
  C. 2
  D. 3
  A. 1

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  Explanation

  Type 1 https://en.wikipedia.org/wiki/NSA_cryptography#Type_1_Product A Type 1 Product refers to an NSA endorsed classified or controlled cryptographic item for classified or sensitive U.S. government information, including cryptographic equipment, assembly or component classified or certified by NSA for encrypting and decrypting classified and sensitive national security information when appropriately keyed.