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

• Question 181:

  Which of the following statements is most true regarding binary operations and encryption?

  A. They can provide secure encryption

  B. They are only useful as a teaching method

  C. They can form a part of viable encryption methods

  D. They are completely useless

  Correct Answer: C

  They can form a part of viable encryption methods for example - https://en.wikipedia.org/wiki/XOR_cipher The XOR operator is extremely common as a component in more complex ciphers. By itself, using a constant repeating key, a simple XOR cipher can trivially be broken using frequency analysis. If the content of any message can be guessed or otherwise known then the key can be revealed. Its primary merit is that it is simple to implement, and that the XOR operation is computationally inexpensive. A simple repeating XOR

  (i.e. using the same key for xor operation on the whole data) cipher is therefore sometimes used for hiding information in cases where no particular security is required. The XOR cipher is often used in computer malware to make reverse engineering more difficult.

• Question 182:

  A _____ is a function is not reversible.

  A. Stream cipher

  B. Asymmetric cipher

  C. Hash

  D. Block Cipher

  Correct Answer: C

  Hash https://en.wikipedia.org/wiki/Hash_function Hash functions are irreversible. This is actually required for them to fulfill their function of determining whether someone possesses an uncorrupted copy of the hashed data. This brings susceptibility to brute force attacks, which are quite powerful these days, particularly against MD5.

• Question 183:

  Which of the following would be the weakest encryption algorithm?

  A. DES

  B. AES

  C. RSA

  D. EC

  Correct Answer: A

  DES https://en.wikipedia.org/wiki/Data_Encryption_Standard DES is insecure due to the relatively short 56-bit key size. In January 1999, distributed.net and the Electronic Frontier Foundation collaborated to publicly break a DES key in 22 hours and 15 minutes.

• Question 184:

  A disk you rotated to encrypt/decrypt. Created by Leon Alberti. Similar technologies were used in the Enigma machine. Considered the forefather of modern encryption.

  A. Chi Square

  B. Enigma Machine

  C. Cipher Disks

  D. Scytale Cipher

  Correct Answer: C

  Cipher disks https://en.wikipedia.org/wiki/Cipher_disk A cipher disk is an enciphering and deciphering tool developed in 1470 by the Italian architect and author Leon Battista Alberti. He constructed a device, (eponymously called the Alberti cipher disk) consisting of two concentric circular plates mounted one on top of the other. The larger plate is called the "stationary" and the smaller one the "moveable" since the smaller one could move on top of the "stationary".

• Question 185:

  All of the following are key exchange protocols except for____

  A. MQV

  B. AES

  C. ECDH

  D. DH

  Correct Answer: B

• Question 186:

  Ferris has been assigned the task of selecting security for his company's wireless network. It is important that he pick the strongest form of wireless security. Which one of the following is the strongest wireless security?

  A. WEP

  B. WPA

  C. WPA2

  D. TKIP

  Correct Answer: C

  WPA2 https://en.wikipedia.org/wiki/Wi-Fi_Protected_Access WPA (sometimes referred to as the draft IEEE 802.11i standard) became available in 2003. The Wi-Fi Alliance intended it as an intermediate measure in anticipation of the availability of the more secure and complex WPA2, which became available in 2004 and is a common shorthand for the full IEEE 802.11i (or IEEE 802.11i-2004) standard.

• Question 187:

  Electromechanical rotor-based cipher used in World War II

  A. ROT13 Cipher

  B. Cipher Disk

  C. Enigma Machine

  D. Rail Fence Cipher

  Correct Answer: C

  Enigma Machine https://en.wikipedia.org/wiki/Enigma_machine The Enigma machine is an encryption device developed and used in the early- to mid-20th century to protect commercial, diplomatic and military communication. It was employed extensively by Nazi Germany during World War II, in all branches of the German military. Enigma has an electromechanical rotor mechanism that scrambles the 26 letters of the alphabet.

• Question 188:

  Which of the following is used to encrypt email and create digital signatures?

  A. DES

  B. SHA1

  C. AES

  D. RSA

  Correct Answer: D

  RSA https://en.wikipedia.org/wiki/RSA_(cryptosystem) RSA use for encryption email and create digital signatures

• Question 189:

  The time and effort required to break a security measure.

  A. Session Key

  B. Work factor

  C. Non-repudiation

  D. Payload

  Correct Answer: B

  Work factor

  Work factor - the time and effort required to break a security measure.

• Question 190:

  Which of the following uses an 80 bit key on 64 bit blocks?

  A. Skipjack

  B. Twofish

  C. DES

  D. AES

  Correct Answer: A

  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.