QUESTION: 33

If you wished to see a list of revoked certificates from a CA, where would you look?

Answer(s): C

Explanation:

CRL
https://ru.wikipedia.org/wiki/Certificate_Revocation_List
Certificate Revocation List (or CRL) is "a list of digital certificates that have been revoked by the issuing certificate authority (CA) before their scheduled expiration date and should no longer be trusted".

Incorrect answers:
RA - Used to proxy the certificate requests on behalf of the user and validate whether or not they are legitimate instead of having the user go directly to the CA. The RA talks to the subordinate CA on behalf of the user, which makes it harder for the actor to get directly to the certificate authority and do harm.
RFC – Request for Comments (RFC) is a publication from the Internet Society (ISOC) and its associated bodies, most prominently the Internet Engineering Task Force (IETF), the principal technical development and standards-setting bodies for the Internet.
CA - certificate authority or certification authority is an entity that issues digital certificates

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QUESTION: 34

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

Answer(s): A,C,D

Explanation:

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.

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QUESTION: 35

A cipher is defined as what

The algorithm(s) needed to encrypt and decrypt a message
Encrypted text
The key used to encrypt a message
Any algorithm used in cryptography

Answer(s): A

Explanation:

The algorithm(s) needed to encrypt and decrypt a message https://en.wikipedia.org/wiki/Cipher
In cryptography, a cipher (or cypher) is an algorithm for performing encryption or decryption—a series of well-defined steps that can be followed as a procedure. An alternative, less common term is encipherment. To encipher or encode is to convert information into cipher or code. In common parlance, "cipher" is synonymous with "code", as they are both a set of steps that encrypt a message; however, the concepts are distinct in cryptography, especially classical cryptography.

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QUESTION: 36

A measure of the uncertainty associated with a random variable.

Collision
Whitening
Diffusion
Entropy

Answer(s): D

Explanation:

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".

Incorrect answers:
Diffusion - transposition processes used in encryption functions to increase randomness.
Whitening - technique intended to increase the security of an iterated block cipher. It consists of steps that combine the data with portions of the key.
Collision - situation where two different inputs yield the same output.

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QUESTION: 33

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