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NEW QUESTION # 114
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 # 115
A protocol for key aggreement based on Diffie-Hellman. Created in 1995. Incorporated into the public key standard IEEE P1363.
- A. Elliptic Curve
- B. Blum Blum Shub
- C. Euler's totient
- D. Menezes-Qu-Vanstone
Answer: D
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 # 116
Network of trusted certificate authority servers. Use asymmetric key pairs and combines software, encryption and services to provide a means of protecting security of business communication and transactions.
- A. PIKE
- B. CA
- C. PKI
- D. GOST
Answer: C
Explanation:
PKI
https://en.wikipedia.org/wiki/Public_key_infrastructure
A public key infrastructure (PKI) is a set of roles, policies, hardware, software and procedures needed to create, manage, distribute, use, store and revoke digital certificates and manage public-key encryption. The purpose of a PKI is to facilitate the secure electronic transfer of information for a range of network activities such as e-commerce, internet banking and confidential email. It is required for activities where simple passwords are an inadequate authentication method and more rigorous proof is required to confirm the identity of the parties involved in the communication and to validate the information being transferred.
Incorrect answers:
PIKE - stream cipher was invented by Ross Anderson to be a "leaner and meaner" version of FISH after he broke FISH in 1994. Its name is supposed to be a humorous allusion to the pike fish.
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.
CA - certificate authority or certification authority (CA) is an entity that issues digital certificates. A digital certificate certifies the ownership of a public key by the named subject of the certificate. This allows others (relying parties) to rely upon signatures or on assertions made about the private key that corresponds to the certified public key. A CA acts as a trusted third party-trusted both by the subject (owner) of the certificate and by the party relying upon the certificate. The format of these certificates is specified by the X.509 or EMV standard.
NEW QUESTION # 117
Which of the following would be the weakest encryption algorithm?
- A. EC
- B. RSA
- C. AES
- D. DES
Answer: D
Explanation:
DES
https://en.wikipedia.org/wiki/Data_Encryption_Standard
DES is insecure due to the relatively short 56-bit key size. In January 1999, distributed.net and the Electronic Frontier Foundation collaborated to publicly break a DES key in 22 hours and 15 minutes.
Incorrect answers:
AES - has been adopted by the U.S. government and is now used worldwide. It supersedes the Data Encryption Standard (DES),which was published in 1977. The algorithm described by AES is a symmetric-key algorithm, meaning the same key is used for both encrypting and decrypting the data.
RSA - The security of RSA relies on the practical difficulty of factoring the product of two large prime numbers, the "factoring problem". Breaking RSA encryption is known as the RSA problem. Whether it is as difficult as the factoring problem is an open question. There are no published methods to defeat the system if a large enough key is used.
EC - Elliptic-curve cryptography (ECC) is 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.
NEW QUESTION # 118
You are explaining the details of the AES algorithm to cryptography students. You are discussing the derivation of the round keys from the shared symmetric key. The portion of AES where round keys are derived from the cipher key using Rijndael's key schedule is called what?
- A. The initial round
- B. The bit shifting phase
- C. The round key phase
- D. The key expansion phase
Answer: D
Explanation:
The key expansion phase
https://en.wikipedia.org/wiki/Advanced_Encryption_Standard
KeyExpansion - round keys are derived from the cipher key using the AES key schedule. AES requires a separate 128-bit round key block for each round plus one more.
NEW QUESTION # 119
A _____ is a function that takes a variable-size input m and returns a fixed-size string.
- A. Hash
- B. Asymmetric cipher
- C. Symmetric cipher
- D. Feistel
Answer: A
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 # 120
A part of understanding symmetric cryptography understands the modes in which it can be used. You are explaining those modes to a group of cryptography students. The most basic encryption mode is____________.
The message is divided into blocks, and each block is encrypted separately with no modification to the process.
- A. Electronic codebook (ECB)
- B. Output feedback (OFB)
- C. Cipher block chaining (CBC)
- D. Cipher feedback (CFB)
Answer: A
NEW QUESTION # 121
Nicholas is working at a bank in Germany. He is looking at German standards for pseudo random number generators. He wants a good PRNG for generating symmetric keys. The German Federal Office for Information Security (BSI) has established four criteria for quality of random number generators. Which ones can be used for cryptography?
- A. K2
- B. K5
- C. K3
- D. K1
- E. K4
Answer: C,E
Explanation:
K3 and K4
https://en.wikipedia.org/wiki/Pseudorandom_number_generator
The German Federal Office for Information Security (Bundesamt für Sicherheit in der Informationstechnik, BSI) has established four criteria for quality of deterministic random number generators.They are summarized here:
K1 - There should be a high probability that generated sequences of random numbers are different from each other.
K2 - A sequence of numbers is indistinguishable from "truly random" numbers according to specified statistical tests. The tests are the monobit test (equal numbers of ones and zeros in the sequence), poker test (a special instance of the chi-squared test), runs test (counts the frequency of runs of various lengths), longruns test (checks whether there exists any run of length 34 or greater in 20 000 bits of the sequence)-both from BSI and NIST, and the autocorrelation test. In essence, these requirements are a test of how well a bit sequence: has zeros and ones equally often; after a sequence of n zeros (or ones), the next bit a one (or zero) with probability one-half; and any selected subsequence contains no information about the next element(s) in the sequence.
K3 - It should be impossible for an attacker (for all practical purposes) to calculate, or otherwise guess, from any given subsequence, any previous or future values in the sequence, nor any inner state of the generator.
K4 - It should be impossible, for all practical purposes, for an attacker to calculate, or guess from an inner state of the generator, any previous numbers in the sequence or any previous inner generator states.
For cryptographic applications, only generators meeting the K3 or K4 standards are acceptable.
NEW QUESTION # 122
Ferris has been assigned the task of selecting security for his company's wireless network. It is important that he pick the strongest form of wireless security. Which one of the following is the strongest wireless security?
- A. WPA
- B. WPA2
- C. WEP
- D. TKIP
Answer: B
Explanation:
WPA2
https://en.wikipedia.org/wiki/Wi-Fi_Protected_Access
WPA (sometimes referred to as the draft IEEE 802.11i standard) became available in 2003. The Wi-Fi Alliance intended it as an intermediate measure in anticipation of the availability of the more secure and complex WPA2, which became available in 2004 and is a common shorthand for the full IEEE 802.11i (or IEEE 802.11i-2004) standard.
NEW QUESTION # 123
Which one of the following is an example of a symmetric key algorithm?
- A. ECC
- B. RSA
- C. Diffie-Hellman
- D. Rijndael
Answer: D
Explanation:
Rijndael
https://en.wikipedia.org/wiki/Advanced_Encryption_Standard
The Advanced Encryption Standard (AES), also known by its original name Rijndael. The algorithm described by AES is a symmetric-key algorithm, meaning the same key is used for both encrypting and decrypting the data.
Incorrect answers:
ECC - Elliptic-curve cryptography is 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.
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.
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.
NEW QUESTION # 124
Which component of IPsec performs protocol-level functions that are required to encrypt and decrypt the packets?
- A. Internet Key Exchange (IKE)
- B. Oakley
- C. IPsec driver
- D. IPsec Policy Agent
Answer: A
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 # 125
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 # 126
Part of understanding cryptography is understanding the cryptographic primitives that go into any crypto system. A(n) _______ is a fixed-size input to a cryptographic primitive that is random or pseudorandom.
- A. Chain
- B. IV
- C. Key
- D. Salt
Answer: C
Explanation:
Key
https://en.wikipedia.org/wiki/Key_(cryptography)
In cryptography, a key is a piece of information (a parameter) that determines the functional output of a cryptographic algorithm. For encryption algorithms, a key specifies the transformation of plaintext into ciphertext, and vice versa for decryption algorithms. Keys also specify transformations in other cryptographic algorithms, such as digital signature schemes and message authentication codes.
NEW QUESTION # 127
What is a variation of DES that uses a technique called Key Whitening?
- A. 3DES
- B. DESX
- C. Blowfish
- D. AES
Answer: B
Explanation:
DESX
https://en.wikipedia.org/wiki/DES-X
In cryptography, DES-X (or DESX) is a variant on the DES (Data Encryption Standard) symmetric-key block cipher intended to increase the complexity of a brute-force attack using a technique called key whitening.
NEW QUESTION # 128
In a ______ the attacker discovers a functionally equivalent algorithm for encryption and decryption, but without learning the key.
- A. Global deduction
- B. Total break
- C. Instance deduction
- D. Information deduction
Answer: B
Explanation:
Global deduction
https://en.wikipedia.org/wiki/Cryptanalysis
Global deduction - the attacker discovers a functionally equivalent algorithm for encryption and decryption, but without learning the key.
Incorrect answers:
Instance (local) deduction - the attacker discovers additional plaintexts (or ciphertexts) not previously known.
Information deduction - the attacker gains some Shannon information about plaintexts (or ciphertexts) not previously known.
Total break - the attacker deduces the secret key.
NEW QUESTION # 129
Cylinder tool. Wrap leather around to decode. The diameter is the key. Used in 7th century BC by greek poet Archilochus.
- A. Scytale
- B. Caesar cipher
- C. Cipher disk
- D. Enigma machine
Answer: A
Explanation:
Scytale
https://en.wikipedia.org/wiki/Scytale
A scytale is a tool used to perform a transposition cipher, consisting of a cylinder with a strip of parchment wound around it on which is written a message. The ancient Greeks, and the Spartans in particular, are said to have used this cipher in 7th century BC to communicate during military campaigns.
The recipient uses a rod of the same diameter on which the parchment is wrapped to read the message. It has the advantage of being fast and not prone to mistakes-a necessary property when on the battlefield. It can, however, be easily broken. Since the strip of parchment hints strongly at the method, the ciphertext would have to be transferred to something less suggestive, somewhat reducing the advantage noted.
Incorrect answers:
Cipher disk - is an enciphering and deciphering tool developed in 1470 by the Italian architect and author Leon Battista Alberti. He constructed a device, (eponymously called the Alberti cipher disk) consisting of two concentric circular plates mounted one on top of the other. The larger plate is called the "stationary" and the smaller one the "moveable" since the smaller one could move on top of the "stationary".
Enigma machine - is an encryption device developed and used in the early- to mid-20th century to protect commercial, diplomatic and military communication. It was employed extensively by Nazi Germany during World War II, in all branches of the German military.
Caesar cipher - (also known as Caesar's cipher, the shift cipher, Caesar's code or Caesar shift) is one of the simplest and most widely known encryption techniques. It is a type of substitution cipher in which each letter in the plaintext is replaced by a letter some fixed number of positions down the alphabet. For example, with a left shift of 3, D would be replaced by A, E would become B, and so on. The method is named after Julius Caesar, who used it in his private correspondence.
NEW QUESTION # 130
Which one of the following best describes a process that splits the block of plaintext into two separate blocks, then applies the round function to one half, and finally swaps the two halves?
- A. Block ciphers
- B. Feistel cipher
- C. Symmetric cryptography
- D. Substitution cipher
Answer: B
Explanation:
Correct answer:
https://en.wikipedia.org/wiki/Feistel_cipher
Feistel cipher (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); it is also commonly known as a Feistel network. A large proportion of block ciphers use the scheme, including the US Data Encryption Standard, the Soviet-developed GOST and the more recent Blowfish and Twofish ciphers. In a Feistel cipher, encryption and decryption are very similar operations, and both consist of iteratively running a function called a "round function" a fixed number of times.
Incorrect answers:
Symmetric cryptography - Symmetric-key algorithms are algorithms for cryptography that use the same cryptographic keys for both encryption of plaintext and decryption of ciphertext. The keys may be identical or there may be a simple transformation to go between the two keys.
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.
Block ciphers - block cipher is a deterministic algorithm operating on fixed-length groups of bits, called blocks. It uses an unvarying transformation, that is, it uses a symmetric key. They are specified elementary components in the design of many cryptographic protocols and are widely used to implement the encryption of large amounts of data, including data exchange protocols.
NEW QUESTION # 131
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. Blowfish
- B. RC4
- C. FISH
- D. Twofish
Answer: C
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 # 132
With Cipher feedback (CFB) what happens?
- A. The message is divided into blocks and each block is encrypted separately. This is the most basic mode for symmetric encryption
- B. The key is reapplied
- C. The block cipher is turned into a stream cipher
- D. The ciphertext block is encrypted then the ciphertext produced is XOR'd back with the plaintext to produce the current ciphertext block
Answer: D
Explanation:
The ciphertext block is encrypted then the ciphertext produced is XOR'd back with the plaintext to produce the current ciphertext block
https://en.wikipedia.org/wiki/Block_cipher_mode_of_operation#Cipher_feedback_(CFB) The cipher feedback (CFB) mode, a close relative of CBC, makes a block cipher into a self-synchronizing stream cipher.
NEW QUESTION # 133
Collision resistance is an important property for any hashing algorithm. Joan wants to find a cryptographic hash that has strong collision resistance. Which one of the following is the most collisionresistant?
- A. PIKE
- B. MD4
- C. SHA2
- D. MD5
Answer: C
Explanation:
SHA2
https://en.wikipedia.org/wiki/Collision_resistance
Collision resistance is a property of cryptographic hash functions: a hash function H is collision-resistant if it is hard to find two inputs that hash to the same output; that is, two inputs a and b where a ≠ b but H(a) = H(b). The pigeonhole principle means that any hash function with more inputs than outputs will necessarily have such collisions; the harder they are to find, the more cryptographically secure the hash function is.
Due to the Birthday Problem, for a hash function that produces an output of length n bits, the probability of getting a collision is 1/2^n/2.
So, just looking for a hash function with larger "n".
The SHA-2 family consists of six hash functions with digests (hash values) that are 224, 256, 384 or 512 bits: SHA-224, SHA-256, SHA-384, SHA-512, SHA-512/224, SHA-512/256.
NEW QUESTION # 134
You are trying to find a modern method for security web traffic for use in your company's ecommerce web site. Which one of the following is used to encrypt web pages and uses bilateral authentication?
- A. 3DES
- B. AES
- C. TLS
- D. SSL
Answer: C
Explanation:
TLS
https://en.wikipedia.org/wiki/Mutual_authentication
Mutual authentication or two-way authentication refers to two parties authenticating each other at the same time, being a default mode of authentication in some protocols (IKE, SSH) and optional in others (TLS).
By default the TLS protocol only proves the identity of the server to the client using X.509 certificate and the authentication of the client to the server is left to the application layer. TLS also offers client-to-server authentication using client-side X.509 authentication. As it requires provisioning of the certificates to the clients and involves less user-friendly experience, it's rarely used in end-user applications.
NEW QUESTION # 135
What is the basis for the FISH algorithm?
- A. Prime number theory
- B. Equations that describe an ellipse
- C. The difficulty in factoring numbers
- D. The Lagged Fibonacci generator
Answer: D
Explanation:
The Lagged Fibonacci generator
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 # 136
The art and science of writing hidden messages so that no one suspects the existence of the message, a type of security through obscurity. Message can be hidden in picture or audio file for example. Uses least significant bits in a file to store data.
- A. Cryptosystem
- B. Avalanche effect
- C. Steganography
- D. Key Schedule
Answer: C
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 first recorded use of the term was in 1499 by Johannes Trithemius in his Steganographia, a treatise on cryptography and steganography, disguised as a book on magic. Generally, the hidden messages appear to be (or to be part of) something else: images, articles, shopping lists, or some other cover text. For example, the hidden message may be in invisible ink between the visible lines of a private letter. Some implementations of steganography that lack a shared secret are forms of security through obscurity, and key-dependent steganographic schemes adhere to Kerckhoffs's principle.
Incorrect answers:
Avalanche effect - the desirable property of cryptographic algorithms, typically block ciphers and cryptographic hash functions, wherein if an input is changed slightly (for example, flipping a single bit), the output changes significantly (e.g., half the output bits flip). In the case of high-quality block ciphers, such a small change in either the key or the plaintext should cause a drastic change in the ciphertext.
Cryptosystem - a suite of cryptographic algorithms needed to implement a particular security service, most commonly for achieving confidentiality (encryption) Key Schedule - an algorithm for the key that calculates the subkeys for each round that the encryption goes through.
NEW QUESTION # 137
Jane is looking for an algorithm to ensure message integrity. Which of following would be an acceptable choice?
- A. RSA
- B. RC4
- C. AES
- D. SHA-1
Answer: D
Explanation:
Integrity. In information security, data integrity means maintaining and assuring the accuracy and completeness of data over its entire lifecycle. This means that data cannot be modified in an unauthorized or undetected manner.
An important application of hashes is verification of message integrity. Comparing message digests (hash digests over the message) calculated before, and after, transmission can determine whether any changes have been made to the message or file.
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.
Incorrect answers:
RSA (Rivest-Shamir-Adleman) is one of the first public-key cryptosystems and is widely used for secure data transmission.
RC4 (Rivest Cipher 4 also known as ARC4 or ARCFOUR meaning Alleged RC4, see below) is a stream cipher.
AES (Advanced Encryption Standard) is a subset of the Rijndael block cipher
NEW QUESTION # 138
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