Try Free and Start Using Realistic Verified 212-81 Dumps Instantly [Q28-Q49]

Try Free and Start Using Realistic Verified 212-81 Dumps Instantly

212-81 Actual Questions - Instant Download 208 Questions

NEW QUESTION # 28
Which component of IPsec performs protocol-level functions that are required to encrypt and decrypt the packets?

• A. Oakley
• B. Internet Key Exchange (IKE)
• C. IPsec Policy Agent
• D. IPsec driver

Answer: B

Explanation:
Internet Key Exchange (IKE)
https://en.wikipedia.org/wiki/Internet_Key_Exchange
Internet Key Exchange (IKE, sometimes IKEv1 or IKEv2, depending on version) is the protocol used to set up a security association (SA) in the IPsec protocol suite. IKE builds upon the Oakley protocol and ISAKMP. IKE uses X.509 certificates for authentication ‒ either pre-shared or distributed using DNS (preferably with DNSSEC) ‒ and a Diffie-Hellman key exchange to set up a shared session secret from which cryptographic keys are derived.
Incorrect answers:
Oakley - the Oakley Key Determination Protocol is a key-agreement protocol that allows authenticated parties to exchange keying material across an insecure connection using the Diffie-Hellman key exchange algorithm. The protocol was proposed by Hilarie K. Orman in 1998, and formed the basis for the more widely used Internet Key Exchange protocol.
IPsec Policy Agent - service provides end-to-end security between clients and servers on TCP/IP networks, manages IPsec policy settings, starts the Internet Key Exchange (IKE), and coordinates IPsec policy settings with the IP security driver.
IPsec driver - wrong!

NEW QUESTION # 29
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. Salt
• B. L2TP
• C. Nonce
• D. IV

Answer: D

Explanation:
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.
Incorrect answers:
L2TP - PPTP combined with L2F (Layer 2 Forwarding) (Cisco proprietary protocol) - Uses EAP, CHAP, MS-CHAP, PAP, or S-PAP for authentication. IPSec is used to provide encryption.
Salt - random bits of data intermixed with the message that is to be hashed.
Nonce - an arbitrary number that can be used just once in a cryptographic communication. It is similar in spirit to a nonce word, hence the name. It is often a random or pseudo-random number issued in an authentication protocol to ensure that old communications cannot be reused in replay attacks. They can also be useful as initialization vectors and in cryptographic hash functions.

NEW QUESTION # 30
What size block does FORK256 use?

• A. 0
• B. 1
• C. 2
• D. 3

Answer: A

Explanation:
512
https://en.wikipedia.org/wiki/FORK-256
FORK-256 was introduced at the 2005 NIST Hash workshop and published the following year.[6] FORK-256 uses 512-bit blocks and implements preset constants that change after each repetition. Each block is hashed into a 256-bit block through four branches that divides each 512 block into sixteen 32-bit words that are further encrypted and rearranged

NEW QUESTION # 31
A digital document that contains a public key and some information to allow your system to verify where that key came from. Used for web servers, Cisco Secure phones, E-Commerce.

• A. Registration Authority
• B. Digital Certificate
• C. Payload
• D. OCSP

Answer: B

Explanation:
Digital Certificate
https://en.wikipedia.org/wiki/Public_key_certificate
A public key certificate, also known as a digital certificate or identity certificate, is an electronic document used to prove the ownership of a public key. The certificate includes information about the key, information about the identity of its owner (called the subject), and the digital signature of an entity that has verified the certificate's contents (called the issuer).
Incorrect answers:
OCSP - Provides certificate validation in real time and will let you know if it is valid or has been revoked.
Registration Authority (RA) - component of PKI that validates the identity of an entity requesting a digital certificate.
Payload - In computing and telecommunications, the payload is the part of transmitted data that is the actual intended message. Headers and metadata are sent only to enable payload delivery. In the steganography - information to be concealed and sent secretly, or the data covertly communicated;

NEW QUESTION # 32
Bruce Schneier is a well-known and highly respected cryptographer. He has developed several pseudo random number generators as well as worked on teams developing symmetric ciphers. Which one of the following is a symmetric block cipher designed in 1993 by Bruce Schneier team that is unpatented?

• A. Pegasus
• B. AES
• C. SHA1
• D. Blowfish

Answer: A

Explanation:
Blowfish
https://en.wikipedia.org/wiki/Blowfish_(cipher)
Blowfish is a symmetric-key block cipher, designed in 1993 by Bruce Schneier and included in many cipher suites and encryption products.

NEW QUESTION # 33
Uses a formula, M_n = 2^n − 1 where n is a prime number, to generate primes. Works for 2, 3, 5, 7 but fails on 11 and on many other n values.

• A. Fibonacci Numbers
• B. Even Numbers
• C. Mersenne Primes
• D. Co-prime Numbers

Answer: C

Explanation:
Correct answers: Mersenne Primes
https://en.wikipedia.org/wiki/Mersenne_prime
Mersenne prime 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.
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.
Co-prime Numbers - 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.

NEW QUESTION # 34
A protocol for key aggreement based on Diffie-Hellman. Created in 1995. Incorporated into the public key standard IEEE P1363.

• A. Blum Blum Shub
• B. Menezes-Qu-Vanstone
• C. Elliptic Curve
• D. Euler's totient

Answer: B

Explanation:
Menezes-Qu-Vanstone
https://en.wikipedia.org/wiki/MQV
MQV (Menezes-Qu-Vanstone) is an authenticated protocol for key agreement based on the Diffie-Hellman scheme. Like other authenticated Diffie-Hellman schemes, MQV provides protection against an active attacker. The protocol can be modified to work in an arbitrary finite group, and, in particular, elliptic curve groups, where it is known as elliptic curve MQV (ECMQV).
MQV was initially proposed by Alfred Menezes, Minghua Qu and Scott Vanstone in 1995. It was modified with Law and Solinas in 1998.
Incorrect answers:
Elliptic Curve - an approach to public-key cryptography based on the algebraic structure of elliptic curves over finite fields. ECC allows smaller keys compared to non-EC cryptography (based on plain Galois fields) to provide equivalent security.
Euler's totient - function counts the positive integers up to a given integer n that are relatively prime to n.
Blum Blum Shub - a pseudorandom number generator proposed in 1986 by Lenore Blum, Manuel Blum and Michael Shub that is derived from Michael
O. Rabin's one-way function.

NEW QUESTION # 35
A simple algorithm that will take the initial key and from that generate a slightly different key each round.

• A. Feistel Network
• B. Diffie-Helman
• 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-Damgård 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 # 36
A _____ is a function that takes a variable-size input m and returns a fixed-size string.

• A. Asymmetric cipher
• B. Symmetric cipher
• C. Feistel
• D. Hash

Answer: D

Explanation:
Hash
https://en.wikipedia.org/wiki/Hash_function
A hash function is any function that can be used to map data of arbitrary size to fixed-size values.

NEW QUESTION # 37
Which of the following Secure Hashing Algorithm (SHA) produces a 160-bit digest from a message with a maximum length of (264-1) bits and resembles the MD5 algorithm?

• A. SHA-2
• B. SHA-3
• C. SHA-0
• D. SHA-1

Answer: D

Explanation:
SHA-1
https://en.wikipedia.org/wiki/SHA-1
SHA-1 (Secure Hash Algorithm 1) is a cryptographic hash function which takes an input and produces a 160-bit (20-byte) hash value known as a message digest - typically rendered as a hexadecimal number, 40 digits long. It was designed by the United States National Security Agency, and is a U.S. Federal Information Processing Standard.
SHA-1 produces a message digest based on principles similar to those used by Ronald L. Rivest of MIT in the design of the MD2, MD4 and MD5 message digest algorithms, but generates a larger hash value (160 bits vs. 128 bits).

NEW QUESTION # 38
What is a TGS?

• A. A protocol for encryption
• B. The server that grants Kerberos tickets
• C. A protocol for key exchange
• D. The server that escrows keys

Answer: B

Explanation:
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.

NEW QUESTION # 39
A measure of the uncertainty associated with a random variable.

• A. Collision
• B. Whitening
• C. Diffusion
• D. Entropy

Answer: 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.

NEW QUESTION # 40
A protocol for key aggreement based on Diffie-Hellman. Created in 1995. Incorporated into the public key standard IEEE P1363.

• A. Blum Blum Shub
• B. Menezes-Qu-Vanstone
• C. Elliptic Curve
• D. Euler's totient

Answer: B

Explanation:
Menezes-Qu-Vanstone
https://en.wikipedia.org/wiki/MQV
MQV (Menezes-Qu-Vanstone) is an authenticated protocol for key agreement based on the Diffie-Hellman scheme. Like other authenticated Diffie-Hellman schemes, MQV provides protection against an active attacker. The protocol can be modified to work in an arbitrary finite group, and, in particular, elliptic curve groups, where it is known as elliptic curve MQV (ECMQV).
MQV was initially proposed by Alfred Menezes, Minghua Qu and Scott Vanstone in 1995. It was modified with Law and Solinas in 1998.
Incorrect answers:
Elliptic Curve - an approach to public-key cryptography based on the algebraic structure of elliptic curves over finite fields. ECC allows smaller keys compared to non-EC cryptography (based on plain Galois fields) to provide equivalent security.
Euler's totient - function counts the positive integers up to a given integer n that are relatively prime to n.
Blum Blum Shub - a pseudorandom number generator proposed in 1986 by Lenore Blum, Manuel Blum and Michael Shub that is derived from Michael O. Rabin's one-way function.

NEW QUESTION # 41
What is the basis for the difficulty in breaking RSA?

• A. The birthday paradox
• B. Factoring numbers
• C. Hashing
• D. Equations that describe an elliptic curve

Answer: B

Explanation:
Factoring numbers
https://en.wikipedia.org/wiki/RSA_(cryptosystem)
RSA (Rivest-Shamir-Adleman) is a public-key cryptosystem that is widely used for secure data transmission. It is also one of the oldest. The acronym RSA comes from the surnames of Ron Rivest, Adi Shamir, and Leonard Adleman, who publicly described the algorithm in 1977. An equivalent system was developed secretly, in 1973 at GCHQ (the British signals intelligence agency), by the English mathematician Clifford Cocks. That system was declassified in 1997.
In a public-key cryptosystem, the encryption key is public and distinct from the decryption key, which is kept secret (private). An RSA user creates and publishes a public key based on two large prime numbers, along with an auxiliary value. The prime numbers are kept secret. Messages can be encrypted by anyone, via the public key, but can only be decoded by someone who knows the prime numbers.

NEW QUESTION # 42
Which of the following is a fundamental principle of cryptography that holds that the algorithm can be publicly disclosed without damaging security?

• A. Babbage's principle
• B. Vigenere's principle
• C. Kerkchoff's principle
• D. Shamir's principle

Answer: C

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 # 43
When learning algorithms, such as RSA, it is important to understand the mathematics being used. In RSA, the number of positive integers less than or equal to some number is critical in key generation. The number of positive integers less than or equal to n that are coprime to n is called ______.

• A. Fermat's prime
• B. Mersenne's number
• C. Euler's totient
• D. Fermat's number

Answer: C

Explanation:
Euler's totient
https://en.wikipedia.org/wiki/Euler%27s_totient_function
In number theory, Euler's totient function counts the positive integers up to a given integer n that are relatively prime to n.
Incorrect answers:
Fibonacci number - 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.
Fermat's number - named after Pierre de Fermat, who first studied them, is a positive integer of the form Fn = 2^2^n+1 where n is a non-negative integer. The first few Fermat numbers are:
3, 5, 17, 257, 65537, 4294967297, 18446744073709551617, ...
Mersenne prime - prime number that is one less than a power of two. That is, it is a prime number of the form Mn = 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.

NEW QUESTION # 44
A _______ product refers to an NSA-endorsed classified or controlled cryptographic item for classified or sensitive U. S. government information, including cryptographic equipment, assembly, or component classified or certified by NSA for encrypting and decrypting classified and sensitive national security information when appropriately keyed

• A. Type 3
• B. Type 1
• C. Type 2
• D. Type 4

Answer: B

Explanation:
Type 1
https://en.wikipedia.org/wiki/NSA_cryptography#Type_1_Product
A Type 1 Product refers to an NSA endorsed classified or controlled cryptographic item for classified or sensitive U.S. government information, including cryptographic equipment, assembly or component classified or certified by NSA for encrypting and decrypting classified and sensitive national security information when appropriately keyed.
Incorrect answers:
Type 2 - product refers to an NSA endorsed unclassified cryptographic equipment, assemblies or components for sensitive but unclassified U.S. government information.
Type 3 - unclassified cryptographic equipment, assembly, or component used, when appropriately keyed, for encrypting or decrypting unclassified sensitive U.S. Government or commercial information, and to protect systems requiring protection mechanisms consistent with standard commercial practices. A Type 3 Algorithm refers to NIST endorsed algorithms, registered and FIPS published, for sensitive but unclassified U.S. government and commercial information.
Type 4 - Algorithm refers to algorithms that are registered by the NIST but are not FIPS published. Unevaluated commercial cryptographic equipment, assemblies, or components that are neither NSA nor NIST certified for any Government usage.

NEW QUESTION # 45
Which of the following equations is related to EC?

• A. Let m = (p-1)(q-1)
• B. Me%n
• C. P = Cd%n
• D. y^2 = x^3 + Ax + B

Answer: D

Explanation:
y^2 = x^3 + Ax + B
https://en.wikipedia.org/wiki/Elliptic-curve_cryptography
For current cryptographic purposes, an elliptic curve is a plane curve over a finite field (rather than the real numbers) which consists of the points satisfying the equation:

NEW QUESTION # 46
Changing some part of the plain text for some matching part of cipher text. Historical algorithms typically use this.

• A. Collision
• B. Transposition
• C. Substitution
• D. Decoding

Answer: C

Explanation:
Substitution
https://en.wikipedia.org/wiki/Substitution_cipher
In cryptography, a substitution cipher is a method of encrypting by which units of plaintext are replaced with ciphertext, according to a fixed system; the "units" may be single letters (the most common), pairs of letters, triplets of letters, mixtures of the above, and so forth. The receiver deciphers the text by performing the inverse substitution.
Incorrect answers:
Decoding - the reverse process from encoding - converting the encoded message back into its plaintext format.
Collision - occurs when a hash function generates the same output for different inputs.
Transposition - a method of encryption by which the positions held by units of plaintext (which are commonly characters or groups of characters) are shifted according to a regular system, so that the ciphertext constitutes a permutation of the plaintext. That is, the order of the units is changed (the plaintext is reordered). Mathematically a bijective function is used on the characters' positions to encrypt and an inverse function to decrypt.

NEW QUESTION # 47
The Clipper chip is notable in the history of cryptography for many reasons. First, it was designed for civilian used secure phones. Secondly, it was designed to use a very specific symmetric cipher. Which one of the following was originally designed to provide built-in cryptography for the Clipper chip?

• A. Serpent
• B. Blowfish
• C. Skipjack
• D. Twofish

Answer: C

Explanation:
Skipjack
https://en.wikipedia.org/wiki/Clipper_chip
The Clipper chip was a chipset that was developed and promoted by the United States National Security Agency (NSA) as an encryption device that secured "voice and data messages" with a built-in backdoor that was intended to "allow Federal, State, and local law enforcement officials the ability to decode intercepted voice and data transmissions.". It was intended to be adopted by telecommunications companies for voice transmission. Introduced in 1993, it was entirely defunct by 1996.
he Clipper chip used a data encryption algorithm called Skipjack to transmit information and the Diffie-Hellman key exchange-algorithm to distribute the cryptokeys between the peers. Skipjack was invented by the National Security Agency of the U.S. Government; this algorithm was initially classified SECRET, which prevented it from being subjected to peer review from the encryption research community. The government did state that it used an 80-bit key, that the algorithm was symmetric, and that it was similar to the DES algorithm. The Skipjack algorithm was declassified and published by the NSA on June 24, 1998. The initial cost of the chips was said to be $16 (unprogrammed) or $26 (programmed), with its logic designed by Mykotronx, and fabricated by VLSI Technology, Inc (see the VLSI logo on the image on this page).

NEW QUESTION # 48
What is the solution to the equation 8 mod 3?

• A. 0
• B. 1
• C. 2
• D. 3

Answer: D

Explanation:
2
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.

NEW QUESTION # 49
......

Download Free Latest Exam 212-81 Certified Sample Questions: https://www.guidetorrent.com/212-81-pdf-free-download.html

Prepare for your exam certification with our 212-81 Certified EC-COUNCIL: https://drive.google.com/open?id=1dNlNH2Q8jIiwLbLdRPV-exRHufbga7Ov