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

EC-COUNCIL 212-81 Online Questions & Answers

• Question 21:

  The reverse process from encoding - converting the encoded message back into its plaintext format.

  A. Substitution
  B. Whitening
  C. Encoding
  D. Decoding
  D. Decoding

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  Explanation

  Decoding

  Decoding - reverse process from encoding,converting the encoded message back into its plaintext format.

• Question 22:

  Which one of the following terms describes two numbers that have no common factors?

  A. Coprime
  B. Fermat's number
  C. Euler's totient
  D. Convergent
  A. Coprime

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  Explanation

  Coprime https://en.wikipedia.org/wiki/Coprime_integers In number theory, two integers a and b are said to be relatively prime, mutually prime, or coprime if the only positive integer (factor) that divides both of them is 1. Consequently, any prime number that divides one of a or b does not divide the other. This is equivalent to their greatest common divisor (gcd) being 1.

• Question 23:

  What is a variation of DES that uses a technique called Key Whitening?

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

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  Explanation

  DESX https://en.wikipedia.org/wiki/DES-X In cryptography, DES-X (or DESX) is a variant on the DES (Data Encryption Standard) symmetric-key block cipher intended to increase the complexity of a brute-force attack using a technique called key whitening.

• Question 24:

  Which one of the following is an authentication method that sends the username and password in cleartext?

  A. PAP
  B. CHAP
  C. Kerberos
  D. SPAP
  A. PAP

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  Explanation

  PAP https://en.wikipedia.org/wiki/Password_Authentication_Protocol Password Authentication Protocol (PAP) is a password-based authentication protocol used by Point to Point Protocol (PPP) to validate users. Almost all network operating system remote servers support PAP. PAP is specified in RFC 1334. PAP is considered a weak authentication scheme (weak schemes are simple and have lighter computational overhead but are much more vulnerable to attack; while weak schemes may have limited application in some constrained environments, they are avoided in general). Among PAP's deficiencies is the fact that it transmits unencrypted passwords (i.e. in plain-text) over the network. PAP is therefore used only as a last resort when the remote server does not support a stronger scheme such as CHAP or EAP.

• Question 25:

  Which of the following is the successor of SSL?

  A. GRE
  B. RSA
  C. IPSec
  D. TLS
  D. TLS

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  Explanation

  TLS

  https://en.wikipedia.org/wiki/Transport_Layer_Security#History_and_development TLS 1.0 was first defined in RFC 2246 in January 1999 as an upgrade of SSL Version 3.0, and written by Christopher Allen and Tim Dierks of Consensus

  Development. As stated in the RFC, "the differences between this protocol and SSL 3.0 are not dramatic, but they are significant enough to preclude interoperability between TLS 1.0 and SSL 3.0". Tim Dierks later wrote that these changes,

  and the renaming from "SSL" to "TLS", were a face-saving gesture to Microsoft, "so it wouldn't look [like] the IETF was just rubberstamping Netscape's protocol".

• Question 26:

  This is a 128 bit hash that is specified by RFC 1321. It was designed by Ron Rivest in 1991 to replace an earlier hash function.

  A. SHA1
  B. SHA-256
  C. RSA
  D. MD5
  D. MD5

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  Explanation

  MD5 https://en.wikipedia.org/wiki/MD5 The MD5 message-digest algorithm is a widely used hash function producing a 128-bit hash value. Although MD5 was initially designed to be used as a cryptographic hash function, it has been found to suffer from extensive vulnerabilities. It can still be used as a checksum to verify data integrity, but only against unintentional corruption. It remains suitable for other non-cryptographic purposes, for example for determining the partition for a particular key in a partitioned database.

  MD5 was designed by Ronald Rivest in 1991 to replace an earlier hash function MD4, and was specified in 1992 as RFC 1321.

• Question 27:

  John is responsible for VPNs at his company. He is using IPSec because it has two different modes. He can choose the mode appropriate for a given situation. What are the two modes of IPSec? (Choose two)

  A. Encrypt mode
  B. Transport mode
  C. Tunnel mode
  D. Decrypt mode
  B. Transport mode
  C. Tunnel mode

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  Explanation

  Correct answers: Transport mode and Tunnel mode

  https://en.wikipedia.org/wiki/IPsec#Modes_of_operation The IPsec protocols AH and ESP can be implemented in a host-to-host transport mode, as well as in a network tunneling mode.

• Question 28:

  Which of the following is an asymmetric algorithm that was first publically described in 1977?

  A. Elliptic Curve
  B. Twofish
  C. DESX
  D. RSA
  D. RSA

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  Explanation

  RSA

  https://en.wikipedia.org/wiki/RSA_(cryptosystem)

  RSA (Rivest璖hamir瑼dleman) is a public-key cryptosystem that is widely used for secure data transmission. It is also one of the oldest. The acronym RSA comes from the surnames of Ron Rivest, Adi Shamir, and Leonard Adleman, who

  publicly described the algorithm in 1977.

• Question 29:

  Changing some part of the plain text for some matching part of cipher text. Historical algorithms typically use this.

  A. Decoding
  B. Substitution
  C. Transposition
  D. Collision
  B. Substitution

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  Explanation

  Substitution

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

  In cryptography, a substitution cipher is a method of encrypting by which units of plaintext are replaced with ciphertext, according to a fixed system; the "units" may be single letters (the most common), pairs of letters, triplets of letters,

  mixtures of the above, and so forth. The receiver deciphers the text by performing the inverse substitution.

• Question 30:

  Which of the following is assured by the use of a hash?

  A. Confidentiality
  B. Availability
  C. Authentication
  D. Integrity
  D. Integrity

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  Explanation

  Integrity https://en.wikipedia.org/wiki/Cryptographic_hash_function#Verifying_the_integrity_of_mess ages_and_files An important application of secure hashes is verification of message integrity. Comparing message digests (hash digests over the message) calculated before, and after, transmission can determine whether any changes have been made to the message or file.