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

• Question 171:

  Message hidden in unrelated text. Sender and receiver have pre-arranged to use a pattern to remove certain letters from the message which leaves only the true message behind.

  A. Caesar Cipher

  B. Null Ciphers

  C. Vigenere Cipher

  D. Playfair Cipher

  Correct Answer: B

  Null Ciphers https://en.wikipedia.org/wiki/Null_cipher A null cipher, also known as concealment cipher, is an ancient form of encryption where the plaintext is mixed with a large amount of non-cipher material. Today it is regarded as a simple form of steganography, which can be used to hide ciphertext.

• Question 172:

  Cryptographic hashes are often used for message integrity and password storage. It is important to understand the common properties of all cryptographic hashes. What is not true about a hash?

  A. Few collisions

  B. Reversible

  C. Variable length input

  D. Fixed length output

  Correct Answer: B

  Reversible https://en.wikipedia.org/wiki/Hash_function Hash functions are not reversible.

• Question 173:

  Which one of the following is an authentication method that sends the username and password in cleartext?

  A. PAP

  B. CHAP

  C. Kerberos

  D. SPAP

  Correct Answer: A

  PAP https://en.wikipedia.org/wiki/Password_Authentication_Protocol Password Authentication Protocol (PAP) is a password-based authentication protocol used by Point to Point Protocol (PPP) to validate users. Almost all network operating system remote servers support PAP. PAP is specified in RFC 1334. PAP is considered a weak authentication scheme (weak schemes are simple and have lighter computational overhead but are much more vulnerable to attack; while weak schemes may have limited application in some constrained environments, they are avoided in general). Among PAP's deficiencies is the fact that it transmits unencrypted passwords (i.e. in plain-text) over the network. PAP is therefore used only as a last resort when the remote server does not support a stronger scheme such as CHAP or EAP.

• Question 174:

  A real time protocol for verifying certificates (and a newer method than CRL).

  A. Online Certificate Status Protocol (OCSP)

  B. Server-based Certificate Validation Protocol (SCVP)

  C. Public Key Infrastructure (PKI)

  D. Registration Authority (RA)

  Correct Answer: A

  Online Certificate Status Protocol (OCSP)

  https://en.wikipedia.org/wiki/Online_Certificate_Status_Protocol The Online Certificate Status Protocol (OCSP) is an Internet protocol used for obtaining the revocation status of an X.509 digital certificate. It is described in RFC 6960 and is on

  the Internet standards track. It was created as an alternative to certificate revocation lists (CRL), specifically addressing certain problems associated with using CRLs in a public key infrastructure (PKI).

• Question 175:

  Manipulating individuals so that they will divulge confidential information, rather than by breaking in or using technical cracking techniques.

  A. Linear cryptanalysis

  B. Replay attack

  C. Side-channel attack

  D. Social engineering attack

  Correct Answer: D

  Social engineering attack https://en.wikipedia.org/wiki/Social_engineering_(security) Social engineering is the psychological manipulation of people into performing actions or divulging confidential information. This differs from social engineering within the social sciences, which does not concern the divulging of confidential information. A type of confidence trick for the purpose of information gathering, fraud, or system access, it differs from a traditional "con" in that it is often one of many steps in a more complex fraud scheme.

• Question 176:

  What is the solution to the equation 8 mod 3?

  A. 1

  B. 4

  C. 3

  D. 2

  Correct Answer: D

  https://en.wikipedia.org/wiki/Modulo_operation The modulo operation returns the remainder or signed remainder of a division, after one number is divided by another (called the modulus of the operation). Given two positive numbers a and n, a modulo n (abbreviated as a mod n) is the remainder of the Euclidean division of a by n, where a is the dividend and n is the divisor. The modulo operation is to be distinguished from the symbol mod, which refers to the modulus (or divisor) one is operating from. For example, the expression "5 mod 2" would evaluate to 1, because 5 divided by 2 has a quotient of 2 and a remainder of 1, while "9 mod 3" would evaluate to 0, because the division of 9 by 3 has a quotient of 3 and a remainder of 0; there is nothing to subtract from 9 after multiplying 3 times 3.

• Question 177:

  What is a TGS?

  A. The server that escrows keys

  B. A protocol for encryption

  C. A protocol for key exchange

  D. The server that grants Kerberos tickets

  Correct Answer: D

  The server that grants Kerberos tickets https://en.wikipedia.org/wiki/Kerberos_(protocol) The client authenticates itself to the Authentication Server (AS) which forwards the username to a key distribution center (KDC). The KDC issues a ticket-granting ticket (TGT), which is time stamped and encrypts it using the ticket-granting service's (TGS) secret key and returns the encrypted result to the user's workstation. This is done infrequently, typically at user logon; the TGT expires at some point although it may be transparently renewed by the user's session manager while they are logged in.

• Question 178:

  Storing private keys with a third party is referred to as what?

  A. Key caching

  B. Key storage

  C. Key banking

  D. Key escrow

  Correct Answer: D

  Key escrow https://en.wikipedia.org/wiki/Key_escrow Key escrow (also known as a "fair" cryptosystem) is an arrangement in which the keys needed to decrypt encrypted data are held in escrow so that, under certain circumstances, an authorized third party may gain access to those keys. These third parties may include businesses, who may want access to employees' secure business-related communications, or governments, who may wish to be able to view the contents of encrypted communications (also known as exceptional access).

• Question 179:

  You are explaining basic mathematics to beginning cryptography students. You are covering the basic math used in RSA. A prime number is defined as

  A. Odd numbers with no divisors

  B. Odd numbers

  C. Any number only divisible by odd numbers

  D. Any number only divisible by one and itself

  Correct Answer: C

  Any number only divisible by one and itself https://en.wikipedia.org/wiki/Prime_number A prime number (or a prime) is a natural number greater than 1 that is not a product of two smaller natural numbers. A natural number greater than 1 that is not prime is called a composite number. For example, 5 is prime because the only ways of writing it as a product, 1 ?5 or 5 ?1, involve 5 itself. However, 4 is composite because it is a product (2 ?2) in which both numbers are smaller than 4. Primes are central in number theory because of the fundamental theorem of arithmetic: every natural number greater than 1 is either a prime itself or can be factorized as a product of primes that is unique up to their order.

• Question 180:

  The next number is derived from adding together the prior two numbers (1, 1, 2, 3, 5, 8, 13, 21, 34, 55, 89).

  A. Odd numbers

  B. Fibonacci Sequence

  C. Fermat pseudoprime

  D. Prime numbers

  Correct Answer: B

  Fibonacci Sequence

  https://en.wikipedia.org/wiki/Fibonacci_number

  In mathematics, the Fibonacci numbers, commonly denoted Fn, form a sequence, called the Fibonacci sequence, such that each number is the sum of the two preceding ones, starting from 0 and 1. That is,

  F0 = 0, F1=1, Fn = Fn-1 + Fn-2; for n > 1.

  The beginning of the sequence is thus:

  0,1, 1, 2, 3, 5, 8, 13, 21, 34, 55, 89, 144...