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NEW QUESTION 86
If you wished to see a list of revoked certificates from a CA, where would you look?
- A. RFC
- B. CRL
- C. RA
- D. CA
Answer: B
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Certificate Revocation List (or CRL) is "a list of digital certificates that have been revoked by the issuing certificate authority (CA) before their scheduled expiration date and should no longer be trusted".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
NEW QUESTION 87
_____ uses at least two different shifts, changing the shift with different letters in the plain text.
- A. Caesar cipher
- B. Atbash
- C. Scytale
- D. multi-alphabet encryption
Answer: D
Explanation:
multi-alphabet encryption
https://en.wikipedia.org/wiki/Polyalphabetic_cipher
Two different shifts create two different alphabets.
For +1 and +2
Plaintext alphabet
A B C D E F G H I J K L M N O P Q R S T U V W X Y Z
2 ciphertext alphabets
B C D E F G H I J K L M N O P Q R S T U V W X Y Z A
C D E F G H I J K L M N O P Q R S T U V W X Y Z A B
Incorrect answers:
Scytale - transposition cipher
Caesar cipher - monoalphabetic cipher
Atbash - monoalphabetic cipher
NEW QUESTION 88
Which of the following is a key exchange protocol?
- A. RSA
- B. MQV
- C. DES
- D. AES
Answer: B
Explanation:
MQV
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).
Incorrect answers:
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.
AES - 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.
DES - Data Encryption Standard is a symmetric-key algorithm for the encryption of digital data.
NEW QUESTION 89
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. Twofish
- B. Serpent
- C. Skipjack
- D. Blowfish
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 90
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 91
You are explaining basic mathematics to beginning cryptography students. You are covering the basic math used in RSA. A prime number is defined as
- A. Any number only divisible by one and itself
- B. Odd numbers with no divisors
- C. Odd numbers
- D. Any number only divisible by odd numbers
Answer: D
Explanation:
Any number only divisible by one and itself
https://en.wikipedia.org/wiki/Prime_number
A prime number (or a prime) is a natural number greater than 1 that is not a product of two smaller natural numbers. A natural number greater than 1 that is not prime is called a composite number. For example, 5 is prime because the only ways of writing it as a product, 1 × 5 or 5 × 1, involve 5 itself. However, 4 is composite because it is a product (2 × 2) in which both numbers are smaller than 4. Primes are central in number theory because of the fundamental theorem of arithmetic: every natural number greater than 1 is either a prime itself or can be factorized as a product of primes that is unique up to their order.
NEW QUESTION 92
What is the formula m^e %n related to?
- A. Encrypting with RSA
- B. Encrypting with EC
- C. Generating Mersenne primes
- D. Decrypting with RSA
Answer: A
Explanation:
Encrypting with RSA
https://en.wikipedia.org/wiki/RSA_(cryptosystem)
RSA Encrypting a message m (number) with the public key (n, e) is calculated:
M' := m^e %n
Incorrect answers:
Decrypting with RSA:
M'' := m^d %n
Generation Mersenne primes:
Mn = 2^n - 1
Encrypting with Elliptic Curve (EC):
y^2 = x^3 + ax + b
NEW QUESTION 93
Ahlen is using a set of pre-calculated hashes to attempt to derive the passwords from a Windows SAM file. What is a set of pre-calculated hashes used to derive a hashed password called?
- A. Hash table
- B. Hash matrix
- C. Rainbow table
- D. Password table
Answer: C
Explanation:
Rainbow table
https://en.wikipedia.org/wiki/Rainbow_table
A rainbow table is a precomputed table for caching the output of cryptographic hash functions, usually for cracking password hashes. Tables are usually used in recovering a key derivation function (or credit card numbers, etc.) up to a certain length consisting of a limited set of characters. It is a practical example of a space-time tradeoff, using less computer processing time and more storage than a brute-force attack which calculates a hash on every attempt, but more processing time and less storage than a simple key derivation function with one entry per hash. Use of a key derivation that employs a salt makes this attack infeasible.
NEW QUESTION 94
RFC 1321 describes what hash?
- A. SHA1
- B. RIPEMD
- C. GOST
- D. MD5
Answer: D
Explanation:
MD5
https://en.wikipedia.org/wiki/MD5
MD5 was designed by Ronald Rivest in 1991 to replace an earlier hash function MD4, and was specified in 1992 as RFC 1321.
NEW QUESTION 95
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. WPA2
- B. TKIP
- C. WPA
- D. WEP
Answer: A
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 96
Which of the following is a substitution cipher used by ancient Hebrew scholars?
- A. Atbash
- B. Vigenere
- C. Caesar
- D. Scytale
Answer: A
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 97
John is going to use RSA to encrypt a message to Joan. What key should he use?
- A. A shared key
- B. A random key
- C. Joan's public key
- D. Joan's private key
Answer: C
Explanation:
Joan's public key
https://en.wikipedia.org/wiki/RSA_(cryptosystem)
Suppose Joahn uses Bob's public key to send him an encrypted message. In the message, she can claim to be Alice but Bob has no way of verifying that the message was actually from Alice since anyone can use Bob's public key to send him encrypted messages. In order to verify the origin of a message, RSA can also be used to sign a message.
Suppose Alice wishes to send a signed message to Bob. She can use her own private key to do so. She produces a hash value of the message, raises it to the power of d (modulo n) (as she does when decrypting a message), and attaches it as a "signature" to the message. When Bob receives the signed message, he uses the same hash algorithm in conjunction with Alice's public key. He raises the signature to the power of e (modulo n) (as he does when encrypting a message), and compares the resulting hash value with the message's actual hash value. If the two agree, he knows that the author of the message was in possession of Alice's private key, and that the message has not been tampered with since.
NEW QUESTION 98
John is trying to explain the basics of cryptography to a group of young, novice, security students. Which one of the following most accurately defines encryption?
- A. Changing a message so it can only be easily read by the intended recipient
- B. Complex mathematics to conceal a message
- C. Changing a message using complex mathematics
- D. Applying keys to a message to conceal it
Answer: A
Explanation:
Changing a message so it can only be easily read by the intended recipient
https://en.wikipedia.org/wiki/Encryption
Encryption is the process of encoding information. This process converts the original representation of the information, known as plaintext, into an alternative form known as ciphertext. Ideally, only authorized parties can decipher a ciphertext back to plaintext and access the original information. Encryption does not itself prevent interference but denies the intelligible content to a would-be interceptor.
NEW QUESTION 99
Original, unencrypted information is referred to as ____.
- A. text
- B. cleartext
- C. ciphertext
- D. plaintext
Answer: D
Explanation:
plaintext
https://en.wikipedia.org/wiki/Plaintext
In cryptography, plaintext usually means unencrypted information pending input into cryptographic algorithms, usually encryption algorithms. Cleartext usually refers to data that is transmitted or stored unencrypted ("in clear").
NEW QUESTION 100
Which of the following asymmetric algorithms is described by U.S. Patent 5,231,668 and FIPS 186
- A. RSA
- B. DSA
- C. RC4
- D. AES
Answer: B
Explanation:
DSA
https://ru.wikipedia.org/wiki/DSA
The National Institute of Standards and Technology (NIST) proposed DSA for use in their Digital Signature Standard (DSS) in 1991, and adopted it as FIPS 186 in 1994.
DSA is covered by U.S. Patent 5,231,668 , filed July 26, 1991 and now expired, and attributed to David W. Kravitz, a former NSA employee.
NEW QUESTION 101
An attack that is particularly successful against block ciphers based on substitution-permutation networks. For a block size b, holds b-k bits constant and runs the other k through all 2k possibilities. For k=1, this is just deferential cryptanalysis, but with k>1 it is a new technique.
- A. Differential Cryptanalysis
- B. Linear Cryptanalysis
- C. Chosen Plaintext Attack
- D. Integral Cryptanalysis
Answer: D
Explanation:
Integral Cryptanalysis
https://en.wikipedia.org/wiki/Integral_cryptanalysis
Integral cryptanalysis is a cryptanalytic attack that is particularly applicable to block ciphers based on substitution-permutation networks. It was originally designed by Lars Knudsen as a dedicated attack against Square, so it is commonly known as the Square attack. It was also extended to a few other ciphers related to Square: CRYPTON, Rijndael, and SHARK. Stefan Lucks generalized the attack to what he called a saturation attack and used it to attack Twofish, which is not at all similar to Square, having a radically different Feistel network structure. Forms of integral cryptanalysis have since been applied to a variety of ciphers, including Hierocrypt, IDEA, Camellia, Skipjack, MISTY1, MISTY2, SAFER++, KHAZAD, and FOX (now called IDEA NXT).
Incorrect answers:
Chosen Plaintext Attack - is an attack model for cryptanalysis which presumes that the attacker can obtain the ciphertexts for arbitrary plaintexts. The goal of the attack is to gain information that reduces the security of the encryption scheme.
Linear Cryptanalysis - is a general form of cryptanalysis based on finding affine approximations to the action of a cipher. Attacks have been developed for block ciphers and stream ciphers. Linear cryptanalysis is one of the two most widely used attacks on block ciphers.
Differential Cryptanalysis - is a general form of cryptanalysis applicable primarily to block ciphers, but also to stream ciphers and cryptographic hash functions. In the broadest sense, it is the study of how differences in information input can affect the resultant difference at the output. In the case of a block cipher, it refers to a set of techniques for tracing differences through the network of transformation, discovering where the cipher exhibits non-random behavior, and exploiting such properties to recover the secret key (cryptography key).
NEW QUESTION 102
Protocol suite provides a method of setting up a secure channel for protected data exchange between two devices.
- A. OCSP
- B. TLS
- C. CLR
- D. IPSec
Answer: D
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 103
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. OCSP
- B. Registration Authority
- C. Digital Certificate
- D. Payload
Answer: C
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 104
Which service in a PKI will vouch for the identity of an individual or company?
- A. KDC
- B. CA
- C. CR
- D. CBC
Answer: B
Explanation:
CA
https://en.wikipedia.org/wiki/Certificate_authority
A 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 105
The next number is derived from adding together the prior two numbers (1, 1, 2, 3, 5, 8, 13, 21, 34, 55, 89).
- A. Odd numbers
- B. Fermat pseudoprime
- C. Fibonacci Sequence
- D. Prime numbers
Answer: C
Explanation:
Fibonacci Sequence
https://en.wikipedia.org/wiki/Fibonacci_number
In mathematics, the Fibonacci numbers, 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. That is, F0 = 0, F1=1, Fn = Fn-1 + Fn-2; for n > 1.
The beginning of the sequence is thus:
0,1, 1, 2, 3, 5, 8, 13, 21, 34, 55, 89, 144...
Incorrect answers:
Prime numbers - numbers that have only 2 factors: 1 and themselves. 2, 3, 5, 7, 11, 13, 17, 19, 23, 29, 31, 37, 41, 43, 47...
Fermat numbers - 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, ...
Odd numbers - any number which cannot be divided by two 1, 3, 5, 7, 9, 11, 13, 15 ...
NEW QUESTION 106
......
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