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

EC-COUNCIL 212-81 Online Questions & Answers

• Question 81:

  Numbers that have no factors in common with another.

  A. Fibonacci Numbers
  B. Even Numbers
  C. Co-prime numbers
  D. Mersenne Primes
  C. Co-prime numbers

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  Explanation

  Correct answers: Co-prime numbers https://en.wikipedia.org/wiki/Coprime_integers Two integers a and b are said to be relatively prime, mutually prime, or coprime if the only positive integer (factor) that evenly 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. The numerator and denominator of a reduced fraction are coprime. The numbers 14 and 25 are coprime, since 1 is their only common divisor. On the other hand, 14 and 21 are not coprime, because they are both divisible by 7.

• Question 82:

  How does Kerberos generate the first secret key in the authentication process?

  A. By generating a random AES key
  B. By creating a hash of the user password
  C. By hashing the user ID, network ID. and salt
  D. By using the user's public key
  B. By creating a hash of the user password

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  Explanation

• Question 83:

  Which one of the following is an example of a symmetric key algorithm?

  A. ECC
  B. Diffie-Hellman
  C. RSA
  D. Rijndael
  D. Rijndael

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  Explanation

  Rijndael https://en.wikipedia.org/wiki/Advanced_Encryption_Standard The Advanced Encryption Standard (AES), also known by its original name Rijndael. The algorithm described by AES is a symmetric-key algorithm, meaning the same key is used for both encrypting and decrypting the data.

• Question 84:

  What is the name of the attack where the attacker obtains the ciphertexts corresponding to a set of plaintexts of his own choosing?

  A. Chosen plaintext
  B. Differential cryptanalysis
  C. Known-plaintext attack
  D. Kasiski examination
  A. Chosen plaintext

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  Explanation

  Chosen plaintext https://en.wikipedia.org/wiki/Chosen-plaintext_attack A chosen-plaintext attack (CPA) is an attack model for cryptanalysis which presumes that the attacker can obtain the ciphertexts for arbitrary plaintexts. The goal of the attack is to gain information that reduces the security of the encryption scheme.

• Question 85:

  Which of the following is required for a hash?

  A. Not vulnerable to a brute force attack
  B. Few collisions
  C. Must use SALT
  D. Not reversible
  E. Variable length input, fixed length output
  F. Minimum key length
  D. Not reversible
  E. Variable length input, fixed length output

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  Explanation

  Correct answers: Variable length input, fixed length output and Not reversible https://en.wikipedia.org/wiki/Hash_function A hash function is any function that can be used to map data of arbitrary size to fixed-size values. The values returned by a hash function are called hash values, hash codes, digests, or simply hashes. The values are used to index a fixed-size table called a hash table. Use of a hash function to index a hash table is called hashing or scatter storage addressing.

• Question 86:

  The most common way steganography is accomplished is via which one of the following?

  A. rsb
  B. Isb
  C. msb
  D. asb
  B. Isb

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  Explanation

  lbs

  https://en.wikipedia.org/wiki/Bit_numbering#:~:text=In%20computing%2C%20the%20least %20significant,number%20is%20even%20or%20odd.

  The least significant bit (LSB) is the bit position in a binary integer giving the units value, that is, determining whether the number is even or odd. The LSB is sometimes referred to as the low-order bit or right-most bit, due to the convention in

  positional notation of writing less significant digits further to the right. It is analogous to the least significant digit of a decimal integer, which is the digit in the ones (right-most) position.

• Question 87:

  A transposition cipher invented 1918 by Fritz Nebel, used a 36 letter alphabet and a modified Polybius square with a single columnar transposition.

  A. ADFVGX Cipher
  B. ROT13 Cipher
  C. Book Ciphers
  D. Cipher Disk
  A. ADFVGX Cipher

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  Explanation

  ADFVGX Cipher https://en.wikipedia.org/wiki/ADFGVX_cipher ADFGVX cipher was a field cipher used by the German Army on the Western Front during World War I. ADFGVX was in fact an extension of an earlier cipher called ADFGX. Invented by Lieutenant Fritz Nebel (1891?977) and introduced in March 1918, the cipher was a fractionating transposition cipher which combined a modified Polybius square with a single columnar transposition.

• Question 88:

  Which of the following is a substitution cipher used by ancient Hebrew scholars?

  A. Atbash
  B. Vigenere
  C. Caesar
  D. Scytale
  A. Atbash

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  Explanation

  Atbash 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.

• Question 89:

  Which of the following is a protocol for exchanging keys?

  A. DH
  B. EC
  C. AES
  D. RSA
  A. DH

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  Explanation

  DH https://en.wikipedia.org/wiki/Diffie%E2%80%93Hellman_key_exchange Diffie璈ellman key exchange is a method of securely exchanging cryptographic keys over a public channel and was one of the first public-key protocols as conceived by Ralph Merkle and named after Whitfield Diffie and Martin Hellman. DH is one of the earliest practical examples of public key exchange implemented within the field of cryptography. Published in 1976 by Diffie and Hellman, this is the earliest publicly known work that proposed the idea of a private key and a corresponding public key.

• Question 90:

  A ______ refers to a situation where two different inputs yield the same output.

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

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  Explanation

  Collision

  https://en.wikipedia.org/wiki/Collision_(computer_science) A collision or clash is a situation that occurs when two distinct pieces of data have the same hash value, checksum, fingerprint, or cryptographic digest.