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

EC-COUNCIL 212-81 Online Questions & Answers

• Question 181:

  A part of understanding symmetric cryptography understands the modes in which it can be used. You are explaining those modes to a group of cryptography students. The most basic encryption mode is____________.

  The message is divided into blocks, and each block is encrypted separately with no modification to the process.

  A. Cipher block chaining (CBC)
  B. Cipher feedback (CFB)
  C. Output feedback (OFB)
  D. Electronic codebook (ECB)
  D. Electronic codebook (ECB)

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  Explanation

• Question 182:

  A symmetric Stream Cipher published by the German engineering firm Seimans in 1993. A software based stream cipher that uses a Lagged Fibonacci generator along with concepts borrowed from shrinking generator ciphers.

  A. DESX
  B. FISH
  C. Twofish
  D. IDEA
  B. FISH

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  Explanation

  FISH

  https://en.wikipedia.org/wiki/FISH_(cipher)

  The FISH (FIbonacci SHrinking) stream cipher is a fast software based stream cipher using Lagged Fibonacci generators, plus a concept from the shrinking generator cipher. It was published by Siemens in 1993. FISH is quite fast in software

  and has a huge key length. However, in the same paper where he proposed Pike, Ross Anderson showed that FISH can be broken with just a few thousand bits of known plaintext.

  Incorrect answers:

  Twofish - symmetric algorithm. Designed by Bruce Schneier, John Kelsey, Doug Whiting, David Wagner, Chris Hall, and Niels Ferguson. Uses a block size of 128 bits and key sizes of 128, 192, or 256 bits. It is a Feistel cipher.

  IDEA - symmetric algorithm. Designed by James Massey and Xuejia Lai. Operates on 64 bit blocks and has a 128 bit key. Consists of 8 identical transformations each round and an output transformation.

  DESX - symmetric algorithm. 64 bit key is appended to data, XOR it, and then apply the DES algorithm.

• Question 183:

  The most widely used asymmetric encryption algorithm is what?

  A. Vigenere
  B. Caesar Cipher
  C. RSA
  D. DES
  C. RSA

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  Explanation

  RSA The RSA encryption algorithm is one of the most widely used public key encryption algorithms that have ever been invented. It was created by the three scientists Ronald Rivest, Adi Shamir, and Leonard Adleman in 1977, and today it is increasingly being used in the network area.

• Question 184:

  Which service in a PKI will vouch for the identity of an individual or company?

  A. CA
  B. CR
  C. KDC
  D. CBC
  A. CA

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  Explanation

  CA

  https://en.wikipedia.org/wiki/Certificate_authority A certificate authority or certification authority (CA) is an entity that issues digital certificates. A digital certificate certifies the ownership of a public key by the named subject of the certificate.

  This allows others (relying parties) to rely upon signatures or on assertions made about the private key that corresponds to the certified public key. A CA acts as a trusted third party--trusted both by the subject (owner) of the certificate and by

  the party relying upon the certificate. The format of these certificates is specified by the X.509 or EMV standard.

• Question 185:

  John is trying to explain the basics of cryptography to a group of young, novice, security students. Which one of the following most accurately defines encryption?

  A. Changing a message using complex mathematics
  B. Applying keys to a message to conceal it
  C. Complex mathematics to conceal a message
  D. Changing a message so it can only be easily read by the intended recipient
  D. Changing a message so it can only be easily read by the intended recipient

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  Explanation

  Changing a message so it can only be easily read by the intended recipient https://en.wikipedia.org/wiki/Encryption Encryption is the process of encoding information. This process converts the original representation of the information, known as plaintext, into an alternative form known as ciphertext. Ideally, only authorized parties can decipher a ciphertext back to plaintext and access the original information. Encryption does not itself prevent interference but denies the intelligible content to a would-be interceptor.

• Question 186:

  Which of the following equations is related to EC?

  A. P = Cd%n
  B. Me%n
  C. y^2 = x^3 + Ax + B
  D. Let m = (p-1)(q-1)
  C. y^2 = x^3 + Ax + B

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  Explanation

  y^2 = x^3 + Ax + B

  https://en.wikipedia.org/wiki/Elliptic-curve_cryptography For current cryptographic purposes, an elliptic curve is a plane curve over a finite field (rather than the real numbers) which consists of the points satisfying the equation:

• Question 187:

  Software for maintaining an on-the-fly-encrypted volume. Data is automatically encrypted right before it is saved, then decrypted right after it is loaded, all w/o user intervention.

  A. VPN
  B. PGP
  C. Cryptool
  D. VeraCrypt
  D. VeraCrypt

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  Explanation

  VeraCrypt https://en.wikipedia.org/wiki/VeraCrypt VeraCrypt is a source-available freeware utility used for on-the-fly encryption (OTFE). It can create a virtual encrypted disk within a file or encrypt a partition or (in Windows) the entire storage device with pre-boot authentication.

• Question 188:

  RFC 1321 describes what hash?

  A. RIPEMD
  B. GOST
  C. SHA1
  D. MD5
  D. MD5

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  Explanation

  MD5 https://en.wikipedia.org/wiki/MD5 MD5 was designed by Ronald Rivest in 1991 to replace an earlier hash function MD4, and was specified in 1992 as RFC 1321.

• Question 189:

  With Cipher feedback (CFB) what happens?

  A. The key is reapplied
  B. The ciphertext block is encrypted then the ciphertext produced is XOR'd back with the plaintext to produce the current ciphertext block
  C. The block cipher is turned into a stream cipher
  D. The message is divided into blocks and each block is encrypted separately. This is the most basic mode for symmetric encryption
  B. The ciphertext block is encrypted then the ciphertext produced is XOR'd back with the plaintext to produce the current ciphertext block

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  Explanation

  The ciphertext block is encrypted then the ciphertext produced is XOR'd back with the plaintext to produce the current ciphertext block https://en.wikipedia.org/wiki/Block_cipher_mode_of_operation#Cipher_feedback_(CFB) The cipher feedback (CFB) mode, a close relative of CBC, makes a block cipher into a self- synchronizing stream cipher.

• Question 190:

  The ATBASH cipher is best described as what type of cipher?

  A. Asymmetric
  B. Symmetric
  C. Substitution
  D. Transposition
  C. Substitution

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  Explanation

  Substitution https://en.wikipedia.org/wiki/Atbash Atbash is a monoalphabetic substitution cipher originally used to encrypt the Hebrew alphabet. It can be modified for use with any known writing system with a standard collating order.