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Updated Oct-2022 Pass 212-81 Exam - Real Practice Test Questions
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NEW QUESTION 35
Juanita is attempting to hide some text into a jpeg file. Hiding messages inside another medium is referred to as which one of the following?
- A. Cryptography
- B. Cryptology
- C. Steganalysis
- D. Steganography
Answer: D
Explanation:
Steganography
https://en.wikipedia.org/wiki/Steganography
Steganography is the practice of concealing a file, message, image, or video within another file, message, image, or video. The word steganography comes from Greek steganographia, which combines the words steganos, meaning "covered or concealed", and -graphia meaning "writing".
Incorrect answers:
Cryptography, or cryptology, is the practice and study of techniques for secure communication in the presence of third parties called adversaries.
Steganalysis - is the study of detecting messages hidden using steganography; this is analogous to cryptanalysis applied to cryptography.
NEW QUESTION 36
Numbers that have no factors in common with another.
- A. Even Numbers
- B. Co-prime numbers
- C. Mersenne Primes
- D. Fibonacci Numbers
Answer: B
Explanation:
Correct answers: Co-prime numbers
https://en.wikipedia.org/wiki/Coprime_integers
Two integers a and b are said to be relatively prime, mutually prime, or coprime if the only positive integer (factor) that evenly divides both of them is 1. Consequently, any prime number that divides one of a or b does not divide the other. This is equivalent to their greatest common divisor (gcd) being 1.
The numerator and denominator of a reduced fraction are coprime. The numbers 14 and 25 are coprime, since 1 is their only common divisor. On the other hand, 14 and 21 are not coprime, because they are both divisible by 7.
Incorrect answers:
Even Numbers - A formal definition of an even number is that it is an integer of the form n = 2k, where k is an integer; it can then be shown that an odd number is an integer of the form n = 2k + 1 (or alternately, 2k - 1). It is important to realize that the above definition of parity applies only to integer numbers, hence it cannot be applied to numbers like 1/2 or 4.201. See the section "Higher mathematics" below for some extensions of the notion of parity to a larger class of "numbers" or in other more general settings.
Fibonacci Numbers - commonly denoted F_n, form a sequence, called the Fibonacci sequence, such that each number is the sum of the two preceding ones, starting from 0 and 1.
Mersenne Primes - is a prime number that is one less than a power of two. That is, it is a prime number of the form M_n = 2^n - 1 for some integer n. They are named after Marin Mersenne, a French Minim friar, who studied them in the early 17th century. If n is a composite number then so is 2^n - 1. Therefore, an equivalent definition of the Mersenne primes is that they are the prime numbers of the form M_p = 2^p - 1 for some prime p.
NEW QUESTION 37
This algorithm was published by the German engineering firm Seimans in 1993. It is a software based stream cipher using Lagged Fibonacci generator along with a concept borrowed from the shrinking generator ciphers.
- A. Twofish
- B. FISH
- C. Blowfish
- D. RC4
Answer: B
Explanation:
FISH
https://en.wikipedia.org/wiki/FISH_(cipher)
The FISH (FIbonacci SHrinking) stream cipher is a fast software based stream cipher using Lagged Fibonacci generators, plus a concept from the shrinking generator cipher. It was published by Siemens in 1993. FISH is quite fast in software and has a huge key length. However, in the same paper where he proposed Pike, Ross Anderson showed that FISH can be broken with just a few thousand bits of known plaintext.
NEW QUESTION 38
Protocol suite provides a method of setting up a secure channel for protected data exchange between two devices.
- A. OCSP
- B. CLR
- C. IPSec
- D. TLS
Answer: C
Explanation:
IPSec
https://en.wikipedia.org/wiki/IPsec
Internet Protocol Security (IPsec) is a secure network protocol suite that authenticates and encrypts the packets of data to provide secure encrypted communication between two computers over an Internet Protocol network. It is used in virtual private networks (VPNs).
Incorrect answers:
OCSP - Online Certificate Status Protocol (OCSP) is an Internet protocol used for obtaining the revocation status of an X.509 digital certificate.
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.
TLS - Transport Layer Security, and its now-deprecated predecessor, Secure Sockets Layer (SSL), are cryptographic protocols designed to provide communications security over a computer network. Several versions of the protocols find widespread use in applications such as web browsing, email, instant messaging, and voice over IP (VoIP). Websites can use TLS to secure all communications between their servers and web browsers.
NEW QUESTION 39
The most widely used digital certificate standard. First issued July 3, 1988. It is a digital document that contains a public key signed by the trusted third party, which is known as a Certificate Authority, or CA.
Relied on by S/MIME. Contains your name, info about you, and a signature of a person who issued the certificate.
- A. X.509
- B. RSA
- C. 0
- D. PAP
- E. ElGamal
Answer: A
Explanation:
https://en.wikipedia.org/wiki/X.509
In cryptography, X.509 is a standard defining the format of public key certificates. X.509 certificates are used in many Internet protocols, including TLS/SSL, which is the basis for HTTPS, the secure protocol for browsing the web. They are also used in offline applications, like electronic signatures. An X.509 certificate contains a public key and an identity (a hostname, or an organization, or an individual), and is either signed by a certificate authority or self-signed. When a certificate is signed by a trusted certificate authority, or validated by other means, someone holding that certificate can rely on the public key it contains to establish secure communications with another party, or validate documents digitally signed by the corresponding private key.
Incorrect answers:
RSA - (Rivest-Shamir-Adleman) is a public-key cryptosystem that is widely used for secure data transmission.
ElGamal - asymmetric key encryption algorithm for public-key cryptography which is based on the Diffie-Hellman key exchange. It was described by Taher Elgamal in 1985.
PAP - used to authenticate users, but is no longer used because the information was sent in cleartext.
NEW QUESTION 40
Which of the following are valid key sizes for AES (choose three)?
- A. 0
- B. 1
- C. 2
- D. 3
- E. 4
- F. 5
Answer: A,B,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.
NEW QUESTION 41
Asymmetric encryption method developed in 1984. It is used in PGP implementations and GNU Privacy Guard Software. Consists of 3 parts: key generator, encryption algorithm, and decryption algorithm.
- A. ElGamal
- B. Tiger
- C. RIPEMD
- D. GOST
Answer: A
Explanation:
ElGamal
https://en.wikipedia.org/wiki/ElGamal_encryption
the ElGamal encryption system is an asymmetric key encryption algorithm for public-key cryptography which is based on the Diffie-Hellman key exchange. It was described by Taher Elgamal in 1985. ElGamal encryption is used in the free GNU Privacy Guard software, recent versions of PGP, and other cryptosystems. The Digital Signature Algorithm (DSA) is a variant of the ElGamal signature scheme, which should not be confused with ElGamal encryption.
Incorrect answers:
Tiger - is a cryptographic hash function designed by Ross Anderson and Eli Biham in 1995 for efficiency on 64-bit platforms. The size of a Tiger hash value is 192 bits. Truncated versions (known as Tiger/128 and Tiger/160) can be used for compatibility with protocols assuming a particular hash size. Unlike the SHA-2 family, no distinguishing initialization values are defined; they are simply prefixes of the full Tiger/192 hash value.
GOST - hash function, defined in the standards GOST R 34.11-94 and GOST 34.311-95 is a 256-bit cryptographic hash function. It was initially defined in the Russian national standard GOST R 34.11-94 Information Technology - Cryptographic Information Security - Hash Function. The equivalent standard used by other member-states of the CIS is GOST 34.311-95.
RIPEMD - is a family of cryptographic hash functions developed in 1992 (the original RIPEMD) and 1996 (other variants). There are five functions in the family: RIPEMD, RIPEMD-128, RIPEMD-160, RIPEMD-256, and RIPEMD-320, of which RIPEMD-160 is the most common.
NEW QUESTION 42
Represents the total number of possible values of keys in a cryptographic algorithm or other security measure, such as a password.
- A. Key Schedule
- B. Key Clustering
- C. Key Exchange
- D. Key Space
Answer: D
Explanation:
Key Space
https://en.wikipedia.org/wiki/Key_space_(cryptography)
Algorithm's key space refers to the set of all possible permutations of a key.
To prevent an adversary from using a brute-force attack to find the key used to encrypt a message, the key space is usually designed to be large enough to make such a search infeasible. On average, half the key space must be searched to find the solution.
Another desirable attribute is that the key must be selected truly randomly from all possible key permutations. Should this not be the case, and the attacker is able to determine some factor that may influence how the key was selected, the search space (and hence also the search time) can be significantly reduced. Humans do not select passwords randomly, therefore attackers frequently try a dictionary attack before a brute force attack, as this approach can often produce the correct answer in far less time than a systematic brute force search of all possible character combinations.
NEW QUESTION 43
Which of the following is a fundamental principle of cryptography that holds that the algorithm can be publicly disclosed without damaging security?
- A. Kerkchoff's principle
- B. Babbage's principle
- C. Shamir's principle
- D. Vigenere's principle
Answer: A
Explanation:
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.
NEW QUESTION 44
The mode makes a block cipher into a synchronous stream cipher. It generates keystream blocks, which are then XORed with the plaintext blocks to get the ciphertext.
- A. Cipher feedback (CFB)
- B. Electronic codebook (ECB)
- C. Output feedback (OFB)
- D. Cipher-block chaining (CBC)
Answer: C
Explanation:
Output feedback (OFB)
https://en.wikipedia.org/wiki/Block_cipher_mode_of_operation#Output_feedback_(OFB) The output feedback (OFB) mode makes a block cipher into a synchronous stream cipher. It generates keystream blocks, which are then XORed with the plaintext blocks to get the ciphertext. Just as with other stream ciphers, flipping a bit in the ciphertext produces a flipped bit in the plaintext at the same location. This property allows many error-correcting codes to function normally even when applied before encryption.
Incorrect answers:
Cipher feedback (CFB) - mode, a close relative of CBC, makes a block cipher into a self-synchronizing stream cipher.
Electronic codebook (ECB) - the simplest of the encryption modes (named after conventional physical codebooks). The message is divided into blocks, and each block is encrypted separately.
Cipher-block chaining (CBC) - Ehrsam, Meyer, Smith and Tuchman invented the cipher block chaining (CBC) mode of operation in 1976. In CBC mode, each block of plaintext is XORed with the previous ciphertext block before being encrypted. This way, each ciphertext block depends on all plaintext blocks processed up to that point. To make each message unique, an initialization vector must be used in the first block.
NEW QUESTION 45
Which of the following is a substitution cipher used by ancient Hebrew scholars?
- A. Vigenere
- B. Scytale
- C. Atbash
- D. Caesar
Answer: C
Explanation:
Atbash
https://en.wikipedia.org/wiki/Atbash
Atbash is a monoalphabetic substitution cipher originally used to encrypt the Hebrew alphabet. It can be modified for use with any known writing system with a standard collating order.
Incorrect answers:
Scytale - Transposition cipher. A staff with papyrus or letter wrapped around it so edges would line up. There would be a stream of characters which would show you your message. When unwound it would be a random string of characters. Would need an identical size staff on other end for other individuals to decode message.
Vigenere - method of encrypting alphabetic text by using a series of interwoven Caesar ciphers, based on the letters of a keyword. It employs a form of polyalphabetic substitution.
Caesar Cipher - Monoalphabetic cipher where letters are shifted one or more letters in either direction. The method is named after Julius Caesar, who used it in his private correspondence.
NEW QUESTION 46
A simple algorithm that will take the initial key and from that generate a slightly different key each round.
- A. Diffie-Helman
- B. Feistel Network
- C. SHA-2
- D. Key Schedule
Answer: D
Explanation:
Key Schedule
https://en.wikipedia.org/wiki/Key_schedule
In cryptography, the so-called product ciphers are a certain kind of cipher, where the (de-)ciphering of data is typically done as an iteration of rounds. The setup for each round is generally the same, except for round-specific fixed values called a round constant, and round-specific data derived from the cipher key called a round key. A key schedule is an algorithm that calculates all the round keys from the key.
Incorrect answers:
Feistel Network - (also known as Luby-Rackoff block cipher) is a symmetric structure used in the construction of block ciphers, named after the German-born physicist and cryptographer Horst Feistel who did pioneering research while working for IBM (USA).
SHA-2 - (Secure Hash Algorithm 2) is a set of cryptographic hash functions designed by the United States National Security Agency (NSA) and first published in 2001. They are built using the Merkle-Damgard structure, from a one-way compression function itself built using the Davies-Meyer structure from a specialized block cipher.
Diffie-Hellman - key exchange is a method of securely exchanging cryptographic keys over a public channel and was one of the first public-key protocols as conceived by Ralph Merkle and named after Whitfield Diffie and Martin Hellman.
NEW QUESTION 47
WPA2 uses AES for wireless data encryption at which of the following encryption levels?
- A. 128 bit and CRC
- B. 128 bit and CCMP
- C. 128 bi and TKIP
- D. 64 bit and CCMP
Answer: B
Explanation:
128 bit and CCMP
Counter Mode with Cipher Block Chaining Message Authentication Code Protocol (CCMP) is an encryption protocol that forms part of the 802.11i standard for wireless local area networks (WLANs), particularly those using WiMax technology. CCMP employs 128-bit keys and a 48-bit initialization vector that minimizes vulnerability to replay attacks.
NEW QUESTION 48
John is responsible for VPNs at his company. He is using IPSec because it has two different modes. He can choose the mode appropriate for a given situation. What are the two modes of IPSec? (Choose two)
- A. Tunnel mode
- B. Decrypt mode
- C. Transport mode
- D. Encrypt mode
Answer: A,C
Explanation:
Correct answers: Transport mode and Tunnel mode
https://en.wikipedia.org/wiki/IPsec#Modes_of_operation
The IPsec protocols AH and ESP can be implemented in a host-to-host transport mode, as well as in a network tunneling mode.
NEW QUESTION 49
A cryptographic hash function which uses a Merkle tree-like structure to allow for immense parallel computation of hashes for very long inputs. Authors claim a performance of 28 cycles per byte for MD6-256 on an Intel Core 2 Duo and provable resistance against differential cryptanalysis.
- A. MD5
- B. TIGER
- C. GOST
- D. MD6
Answer: D
Explanation:
MD6
https://en.wikipedia.org/wiki/MD6
The MD6 Message-Digest Algorithm is a cryptographic hash function. It uses a Merkle tree-like structure to allow for immense parallel computation of hashes for very long inputs. Authors claim a performance of 28 cycles per byte for MD6-256 on an Intel Core 2 Duo and provable resistance against differential cryptanalysis.[2] The source code of the reference implementation was released under MIT license.
Speeds in excess of 1 GB/s have been reported to be possible for long messages on 16-core CPU architecture.
In December 2008, Douglas Held of Fortify Software discovered a buffer overflow in the original MD6 hash algorithm's reference implementation. This error was later made public by Ron Rivest on 19 February 2009, with a release of a corrected reference implementation in advance of the Fortify Report.
NEW QUESTION 50
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