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

• Question 71:

  Which of the following algorithms uses three different keys to encrypt the plain text?

  A. Skipjack

  B. AES

  C. Blowfish

  D. 3DES

  Correct Answer: D

  3DES https://en.wikipedia.org/wiki/Triple_DES Triple DES (3DES) has a three different keys with same size (56-bit).

• Question 72:

  Encryption of the same plain text with the same key results in the same cipher text. Use of an IV that is XORed with the first block of plain text solves this problem.

  A. CFB

  B. GOST

  C. ECB

  D. RC4

  Correct Answer: C

  ECB https://en.wikipedia.org/wiki/Block_cipher_mode_of_operation The simplest of the encryption modes is the electronic codebook (ECB) mode (named after conventional physical codebooks). The message is divided into blocks, and each block is encrypted separately. The disadvantage of this method is a lack of diffusion. Because ECB encrypts identical plaintext blocks into identical ciphertext blocks, it does not hide data patterns well. ECB is not recommended for use in cryptographic protocols. ECB mode can also make protocols without integrity protection even more susceptible to replay attacks, since each block gets decrypted in exactly the same way.

• Question 73:

  A non-secret binary vector used as the initializing input algorithm for encryption of a plaintext block sequence to increase security by introducing additional cryptographic variance.

  A. IV

  B. Salt

  C. L2TP

  D. Nonce

  Correct Answer: A

  IV https://en.wikipedia.org/wiki/Initialization_vector In cryptography, an initialization vector (IV) or starting variable (SV) is a fixed-size input to a cryptographic primitive that is typically required to be random or pseudorandom. Randomization is crucial for encryption schemes to achieve semantic security, a property whereby repeated usage of the scheme under the same key does not allow an attacker to infer relationships between segments of the encrypted message. For block ciphers, the use of an IV is described by the modes of operation. Randomization is also required for other primitives, such as universal hash functions and message authentication codes based thereon.

• Question 74:

  What is Kerchoff's principle?

  A. A minimum of 15 rounds is needed for a Feistel cipher to be secure

  B. Only the key needs to be secret, not the actual algorithm

  C. Both algorithm and key should be kept secret

  D. A minimum key size of 256 bits is necessary for security

  Correct Answer: B

  Only the key needs to be secret, not the actual algorithm https://en.wikipedia.org/wiki/Kerckhoffs%27s_principle Kerckhoffs's principle 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.

• Question 75:

  What size block does AES work on?

  A. 64

  B. 128

  C. 192

  D. 256

  Correct Answer: B

  https://en.wikipedia.org/wiki/Advanced_Encryption_Standard Rijndael is a family of ciphers with different key and block sizes. For AES, NIST selected three members of the Rijndael family, each with a block size of 128 bits, but three different key lengths: 128, 192 and 256 bits.

• Question 76:

  Which of the following is a type of encryption that has two different keys. One key can encrypt the message and the other key can only decrypt it?

  A. Block cipher

  B. Asymmetric

  C. Symmetric

  D. Stream cipher

  Correct Answer: B

  Asymmetric 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 77:

  The reverse process from encoding - converting the encoded message back into its plaintext format.

  A. Substitution

  B. Whitening

  C. Encoding

  D. Decoding

  Correct Answer: D

  Decoding

  Decoding - reverse process from encoding,converting the encoded message back into its plaintext format.

• Question 78:

  Which of the following are valid key sizes for AES (Choose three)?

  A. 192

  B. 56

  C. 256

  D. 128

  E. 512

  F. 64

  Correct Answer: ACD

  Correct answers: 128, 192, 256 https://en.wikipedia.org/wiki/Advanced_Encryption_Standard The Advanced Encryption Standard (AES), also known by its original name Rijndael, is a specification for the encryption of electronic data established by the U.S. National Institute of Standards and Technology (NIST) in 2001. AES is a subset of the Rijndael block cipher developed by two Belgian cryptographers, Vincent Rijmen and Joan Daemen, who submitted a proposal to NIST during the AES selection process. Rijndael is a family of ciphers with different key and block sizes. For AES, NIST selected three members of the Rijndael family, each with a block size of 128 bits, but three different key lengths: 128, 192 and 256 bits.

• Question 79:

  In 2007, this wireless security algorithm was rendered useless by capturing packets and discovering the passkey in a matter of seconds. This security flaw led to a network invasion of TJ Maxx and data theft through a technique known as wardriving.

  Which Algorithm is this referring to?

  A. Wired Equivalent Privacy (WEP)

  B. Wi-Fi Protected Access 2 (WPA2)

  C. Wi-Fi Protected Access (WPA)

  D. Temporal Key Integrity Protocol (TKIP)

  Correct Answer: A

  Wired Equivalent Privacy (WEP) https://en.wikipedia.org/wiki/Wired_Equivalent_Privacy#Weak_security In 2007, Erik Tews, Andrei Pychkine, and Ralf-Philipp Weinmann were able to extend Klein's 2005 attack and optimize it for usage against WEP. With the new attack it is possible to recover a 104-bit WEP key with probability 50% using only 40,000 captured packets. For 60,000 available data packets, the success probability is about 80% and for 85,000 data packets about 95%. Using active techniques like deauth and ARP re-injection, 40,000 packets can be captured in less than one minute under good conditions. The actual computation takes about 3 seconds and 3 MB of main memory on a Pentium-M 1.7 GHz and can additionally be optimized for devices with slower CPUs. The same attack can be used for 40-bit keys with an even higher success probability.

• Question 80:

  Used to take the burden off of a CA by handling verification prior to certificates being issued. Acts as a proxy between user and CA. Receives request, authenticates it and forwards it to the CA.

  A. PKI (Public Key Infrastructure)

  B. TTP (Trusted Third Party)

  C. RA (Registration Authority)

  D. CP (Certificate Policy)

  Correct Answer: C

  RA (Registration Authority)

  https://en.wikipedia.org/wiki/Registration_authority Registration authorities exist for many standards organizations, such as ANNA (Association of National Numbering Agencies for ISIN), the Object Management Group, W3C, IEEE and others.

  In general, registration authorities all perform a similar function, in promoting the use of a particular standard through facilitating its use. This may be by applying the standard, where appropriate, or by verifying that a particular application

  satisfies the standard's tenants. Maintenance agencies, in contrast, may change an element in a standard based on set rules ?such as the creation or change of a currency code when a currency is created or revalued (i.e. TRL to TRY for

  Turkish lira). The Object Management Group has an additional concept of certified provider, which is deemed an entity permitted to perform some functions on behalf of the registration authority, under specific processes and procedures

  documented within the standard for such a role.