EC-COUNCIL EC-COUNCIL Certifications 212-81 Questions & Answers

• Question 81:

  What size block does FORK256 use?

  A. 64

  B. 512

  C. 256

  D. 128

  Correct Answer: B

  https://en.wikipedia.org/wiki/FORK-256 FORK-256 was introduced at the 2005 NIST Hash workshop and published the following year.[6] FORK-256 uses 512-bit blocks and implements preset constants that change after each repetition. Each block is hashed into a 256-bit block through four branches that divides each 512 block into sixteen 32-bit words that are further encrypted and rearranged

• Question 82:

  MD5 can best be described as which one of the following?

  A. Asymmetric algorithm

  B. Hashing algorithm

  C. Digital signature

  D. Symmetric algorithm

  Correct Answer: B

  Hashing algorithm 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.

• Question 83:

  Which of the following is a fundamental principle of cryptography that holds that the algorithm can be publicly disclosed without damaging security?

  A. Vigenere's principle

  B. Shamir's principle

  C. Kerkchoff's principle

  D. Babbage's principle

  Correct Answer: C

  Kerkchoff's principle https://en.wikipedia.org/wiki/Kerckhoffs%27s_principle Kerckhoffs's principle (also called Kerckhoffs's desideratum, assumption, axiom, doctrine or law) of cryptography was stated by Netherlands born cryptographer Auguste Kerckhoffs in the 19th century: A cryptosystem should be secure even if everything about the system, except the key, is public knowledge. Kerckhoffs's principle was reformulated (or possibly independently formulated) by American mathematician Claude Shannon as "the enemy knows the system", i.e., "one ought to design systems under the assumption that the enemy will immediately gain full familiarity with them". In that form, it is called Shannon's maxim. This concept is widely embraced by cryptographers, in contrast to "security through obscurity", which is not.

• Question 84:

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

  A. Confidentiality

  B. Availability

  C. Authentication

  D. Integrity

  Correct Answer: D

  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.

• Question 85:

  Algorithm that was chosen for the Data Encryption Standard, which was altered and renamed Data Encryption Algorithm.

  A. Blowfish

  B. Rijndael

  C. Lucifer

  D. El Gamal

  Correct Answer: C

  Lucifer

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

  Lucifer was a direct precursor to the Data Encryption Standard. One version, alternatively named DTD-1.

• Question 86:

  A measure of the uncertainty associated with a random variable.

  A. Collision

  B. Whitening

  C. Diffusion

  D. Entropy

  Correct Answer: D

  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 87:

  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

  Correct Answer: B

  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 88:

  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

  Correct Answer: A

  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 89:

  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

  Correct Answer: D

  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 90:

  In steganography, ________ is the data to be covertly communicated (in other words, it is the message you wish to hide).

  A. Carrier

  B. Signal

  C. Payload

  D. Channel

  Correct Answer: C

  Payload https://en.wikipedia.org/wiki/Steganography The payload is the data covertly communicated. The carrier is the signal, stream, or data file that hides the payload, which differs from the channel, which typically means the type of input, such as a JPEG image. The resulting signal, stream, or data file with the encoded payload is sometimes called the package, stego file, or covert message. The proportion of bytes, samples, or other signal elements modified to encode the payload is called the encoding density and is typically expressed as a number between 0 and 1.