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

EC-COUNCIL 212-81 Online Questions & Answers

• Question 51:

  Why is quantum computing a threat to RSA?

  A. The processing speed will brute force algorithms
  B. Quantum computers can solve the discrete logarithm problem
  C. Quantum computers can solve the birthday paradox
  D. Quantum computers can factor large integers in polynomial time
  D. Quantum computers can factor large integers in polynomial time

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  Explanation

• Question 52:

  A method for cracking modern cryptography. The attacker obtains the cipher texts corresponding to a set of plain texts of own choosing. Allows the attacker to attempt to derive the key. Difficult but not impossible.

  A. Chosen Plaintext Attack
  B. Steganography
  C. Rainbow Tables
  D. Transposition
  A. Chosen Plaintext Attack

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  Explanation

  Chosen Plaintext Attack 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 53:

  ____________cryptography uses one key to encrypt a message and a different key to decrypt it.

  A. Secure
  B. Asymmetric
  C. Stream
  D. Symmetric
  B. Asymmetric

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  Explanation

  Asymmetric https://en.wikipedia.org/wiki/Public-key_cryptography Public-key cryptography, or asymmetric cryptography, is a cryptographic system that uses pairs of keys: public keys, which may be disseminated widely, and private keys, which are known only to the owner. The generation of such keys depends on cryptographic algorithms based on mathematical problems to produce one-way functions. Effective security only requires keeping the private key private; the public key can be openly distributed without compromising security.

• Question 54:

  Which of the following is an asymmetric algorithm related to the equation y^2 = x^3 + Ax + B?

  A. Blowfish
  B. Elliptic Curve
  C. AES
  D. RSA
  B. Elliptic Curve

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  Explanation

  Elliptic Curve

  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 55:

  Which one of the following attempts to hide data in plain view?

  A. Cryptography
  B. Substitution
  C. Steganography
  D. Asymmetric cryptography
  C. Steganography

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  Explanation

  Steganography https://en.wikipedia.org/wiki/Steganography Steganography is the practice of concealing a file, message, image, or video within another file, message, image, or video. The word steganography comes from Greek steganographia, which combines the words stegan髎 , meaning "covered or concealed", and -graphia meaning "writing".

• Question 56:

  What must occur in order for a cipher to be considered `broken'?

  A. Uncovering the algorithm used
  B. Decoding the key
  C. Finding any method that is more efficient than brute force
  D. Rendering the cipher no longer useable
  C. Finding any method that is more efficient than brute force

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  Explanation

  Finding any method that is more efficient than brute force https://en.wikipedia.org/wiki/Cryptanalysis

  Bruce Schneier notes that even computationally impractical attacks can be considered breaks: "Breaking a cipher simply means finding a weakness in the cipher that can be exploited with a complexity less than brute force."

• Question 57:

  Which algorithm implements an unbalanced Feistel cipher?

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

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  Explanation

  Skipjack

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

  Skipjack uses an 80-bit key to encrypt or decrypt 64-bit data blocks. It is an unbalanced Feistel network with 32 rounds.

• Question 58:

  Juanita is attempting to hide some text into a jpeg file. Hiding messages inside another medium is referred to as which one of the following?

  A. Cryptography
  B. Steganalysis
  C. Cryptology
  D. Steganography
  D. Steganography

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  Explanation

  Steganography https://en.wikipedia.org/wiki/Steganography Steganography is the practice of concealing a file, message, image, or video within another file, message, image, or video. The word steganography comes from Greek steganographia, which combines the words stegan髎, meaning "covered or concealed", and -graphia meaning "writing".

• Question 59:

  What is the basis for the FISH algorithm?

  A. The Lagged Fibonacci generator
  B. Prime number theory
  C. Equations that describe an ellipse
  D. The difficulty in factoring numbers
  A. The Lagged Fibonacci generator

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  Explanation

  The Lagged Fibonacci generator

  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.

• Question 60:

  During the process of encryption and decryption, what keys are shared?

  A. Public keys
  B. Public and private keys
  C. User passwords
  D. Private keys
  A. Public keys

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  Explanation

  Public keys https://en.wikipedia.org/wiki/Public-key_cryptography Public-key cryptography, or asymmetric cryptography, is a cryptographic system that uses pairs of keys: public keys, which may be disseminated widely, and private keys, which are known only to the owner. The generation of such keys depends on cryptographic algorithms based on mathematical problems to produce one-way functions. Effective security only requires keeping the private key private; the public key can be openly distributed without compromising security. In such a system, any person can encrypt a message using the receiver's public key, but that encrypted message can only be decrypted with the receiver's private key.

  Alice and Bob have two keys of their own -- just to be clear, that's four keys total. Each party has their own public key, which they share with the world, and their own private key which they well, which they keep private, of course but, more than that, which they keep as a closely guarded secret. The magic of public key cryptography is that a message encrypted with the public key can only be decrypted with the private key. Alice will encrypt her message with Bob's public key, and even though Eve knows she used Bob's public key, and even though Eve knows Bob's public key herself, she is unable to decrypt the message. Only Bob, using his secret key, can decrypt the message assuming he's kept it secret, of course.

  Alice and Bob do not need to plan anything ahead of time to communicate securely: they generate their public-private key pairs independently, and happily broadcast their public keys to the world at large. Alice can rest assured that only Bob can decrypt the message she sends because she has encrypted it with his public key.