WGU C839 – Intro to Cryptography EXAM STUDY BUNDLE 2023 – 2024 (COMPLETE PACKAGE)(Verified)
WGU C839 Objective Assessment: Introduction to Cryptography 2023 – 2024 (Verified Answers)
1.Which encryption standard uses the same key to encrypt and
decrypt messages ANS Symmetric Key Encryption
2.Which algorithm is designated as a Type 2 product by the National
Security Agency (NSA) ANS SKIPJACK
3.What is the most commonly used format for certificates ANS X.509 v3
Version 3
4.What is referenced to determine if a certificate has been revoked ANS
Certifi- cate Revocation List (CRL)
- What needs to be installed on end users’ computers to allow them to
trust applications that have been digitally signed by the developer ANS -Sender’s public key (DEVELOPER’s)
6.Which type of certificate must be certified by an authority to verify it
with other participants ANS Public Certificate
7.What is an attribute of the Rivest Cipher 4 (RC4) algorithm ANS It
requires a unique nonce. (# used ONCE)
8.Which mode generates the key stream with a nonce and
incrementing value ANS Counter (CTR)
Generates the next keystream block by encrypting successive
values of a “counter”
9.Which mode is a stream algorithm that concatenates an
incrementing value with a nonce ANS Counter (CTR)
10.Which key would an administrator use to encrypt data so only the CEO can decrypt it?: CEO’s public key
Remember, when a specific person in an organization is the ONLY
one you want to DECRYPT something, you must have their PUBLIC
key
WGU C839 Objective Assessment 2023 – 2024
1.DES: 64 Bit Block – 56 Bit Key – 16 Rounds
2.AES: 128 Bit Block – 128, 192, 256 Bit Key – 10, 12, 14 Rounds
3.BlowFish: 64 Bit Block – 32 thru 448 Bit Key – 16 Rounds
4.TwoFish: 128 Bit Block – 1 thru 256 Bit Key – 16 Rounds
5.Serpent: 128 Bit Block 128, 192, 256 Bit Key – 32 Rounds
6.SkipJack: 64 Bit Block – 80 Bit Key – 32 Rounds
7.IDEA: 64 Bit Block – 128 Bit Key – 8.5 Rounds
8.Symmetric Block Ciphers: DES – AES – BlowFish – TwoFish –
Serpent – SkipJack – IDEA
9.Symmetric Block Ciphers with 64 Bit Block Size: DES – BlowFish –
SkipJack
- IDEA
10.Symmetric Block Ciphers with 128 Bit Block Size: AES – TwoFish –
Serpent
11.Symmetric Block Ciphers with 128, 192, 256 Bit Key Size: AES – Serpent
12.Symmetric Block Ciphers with 16 Rounds: DES – BlowFish – TwoFish
13.Symmetric Block Ciphers with 32 Rounds: Serpent – SkipJack
14.RC4: 1 thru 2048 Bit Key Size & 1 Round (40 bit minimum
recommended)
15.FISH: Uses Lagged Fibonacci pseudorandom number generator
16.PIKE: Revised version of FISH to address known plaintext attack
vulnerabilities
17.Symmetric Stream Ciphers: RC4 – Fish – Pike
18.Asymmetric Encryption Algos: RSA – ECC – El Gamal – DSA
19.RSA: Leverages prime number characteristics, 1024-4096 bit
variable key size, 1 round. Uses Trapdoor function to enable use for
encryption and digital signatures. One-way trapdoor functions can be
inverted with knowledge of trapdoor factorization information.
20.ECC: Leverages discrete logarithm characteristics
21.El Gamal: Used in recent versions of PGP
1 / 20
WGU C839 Introduction to Cryptography – (EC-Council CES)
1.CrypTool: Software which allows encryption of text using historic
algorithms
2.The Enigma Machine: In World War II the Germans made use of an
electro-me- chanical rotor based cipher Known as The Enigma
Machine.
Allied cipher machines used in WWII included the British TypeX and the
American SIGABA.
3.The ADFGVX Cipher: invented by Colonel Fritz Nebel in 1918.
The key for this algorithm is a six-by-six square of letters, used to
encode a 36-letter alphabet.
4.The Playfair Cipher: invented in 1854 by Charles Wheatstone.
The Playfair cipher uses a five-by-five table containing a keyword or
key phrase.
2 / 20
5.Breaking the Vigene re Ciph:eIrn 1863, Friedrich Kasiski was the first
person to publish a successful general attack on the Vigene re
Cipher
6.The Vigene re Ciph:eTr his is perhaps the most widely known multialphabet substitution cipher. invented in 1553 by Giovan Battista
Bellaso. Uses a series of different Caesar ciphers based on the letters
of a keyword.
7.The Cipher Disk: The cipher disk was invented by Leon Alberti in
- each time you turned the disk, you used a new cipher. It was
literally a disk you turned to encrypt plaintext.
8.Multi-Alphabet Substitution: Use of multiple substitution
alphabets. Example:Cipher Disk, Vigenere Cipher, Enigma
Machine
9.Scytale: This was a cylinder tool used by the Greeks, and is often
specifically attributed to the Spartans. Physical cylinder that was used
to encrypt messages.
10.ROT13 Cipher: It is essentially the Caesar cipher always using a
rotation or shift of 13 characters.
11.The ATBASH Cipher: Hebrew scribes copying religious texts used
this cipher. substitutes the first letter of the alphabet for the
last, and the second letter for the second-to-the-last, etc.
3 / 20
12.The Caesar Cipher: You can choose to shift any number of letters,
either left or right. If you choose to shift two to
the right, that would be a +2; if you choose to shift four to the left, thatwould be a
-4.
13.Mono-Alphabet Substitution: These algorithms
simply substitute one character of cipher text for each character of
plain text.
4 / 20
Examples: Atbash Cipher, Caesar Cipher, Rot13
14.Symmetric Cryptography: It is simply any algorithm where the key
used to decrypt a message is the same key used to encrypt.
15.Diffusion: Changes to one character in the plain text affect multiple
characters in the cipher text.
16.Confusion: Confusion attempts to make the relationship between
the statisti- cal frequencies of the cipher text and the actual key as
complex as possible. This occurs by using a complex substitution
algorithm.
17.Avalanche: a small change yields large effects in the output, This is
Fiestel’s variation on Claude Shannon’s concept of diffusion.
18.Kerckhoffs’s Principle: This principle states that a cryptosystem
should be secure even if everything about the system, except the
key, is publicly known.
19.Substitution: Substitution is changing some part of the plaintext
for some matching part of the Cipher Text.
20.Transposition: Transposition is the swapping of blocks of ciphertext.
21.binary numbers: there are three operations not found in
normal math: AND, OR, and XOR operations.
22.Binary AND: If both numbers have a one in both places, then the
resultant number is a one.
WGU C839 Exam Questions and Answers
2023 – 2024 (Verified Answers)
1.Which encryption standard uses the same key to encrypt and
decrypt messages ANS Symmetric
2.Which algorithm is designated as a Type 2 product by the National
Security Agency (NSA) ANS Skipjack
3.What is the most commonly used format for certificates ANS X.509 v3
4.What is referenced to determine if a certificate has been revoked ANS
Certifi- cate revocation list (CRL)
5.What needs to be installed on end users’ computers to allow them to
trust applications that have been digitally signed by the developer ANS
Sender’s public key
6.Which type of certificate must be certified by an authority to verify it
with other participants ANS Public
7.What is an attribute of the Rivest Cipher 4 (RC4) algorithm ANS It
requires a unique nonce.
8.Which mode generates the key stream with a nonce and
incrementing value ANS Counter (CTR)
9.Which mode is a stream algorithm that concatenates an
incrementing value with a nonce ANS Counter (CTR)
10.Which key would an administrator use to encrypt data so only the
CEO can decrypt it ANS CEO’s public key
11.What is the result of a hash function ANS Digest
12.What is used to efficiently encrypt large files ANS Symmetric
encryption
WGU C839 Exam Study Questions and Answers
2023 – 2024 (Verified Answers)
1.Which encryption standard is approved by the National Security
Agency (NSA) for classified information ANS Advanced Encryption
Standard (AES
2.Which National Security Agency (NSA) encryption algorithms are
uneval- uated commercial cryptographic components ANS Type 4
3.Which method is used to verify the validity of a certificate ANS Online
Certifi- cate Status Protocol (OCSP)
4.What is used to protect an encryption key and deliver it quickly ANS
Digitally signed symmetrical key encryption sent via email
5.Why should a certificate authority (CA) assign an expiration date for
certificates it issues ANS A certificate with a short life span limits how
long data is vulnerable if the key is compromised
6.What is used as a virtual representation that identifies a person as an
entity by a trusted third party ANS Digital signature
7.Which attribute is common to stream ciphers ANS XORing pseudorandom bytes with plaintext
8.Which mode generates a pseudo-random stream of bytes and XORs
the plaintext while encrypting ANS Output feedback (OFB)
9.What is a common attribute of a streaming algorithm ANS It encrypts a
bit at a time.
10.What is required to decrypt data encrypted by a symmetric key ANS
An identical copy of the key
11.Which sender-identifying input must be provided when digitally
signing a message ANS Public key
12.What does m represent, assuming that the encryption function is
WGU C839 – Intro to Cryptography Exam
Questions and Answers
2023 – 2024 (Verified Answers)
- What type of encryption uses different keys to encrypt and decrypt
the message?
A Symmetric
B Private
key C
Secure
D Asymmetric ANS D - The most widely used asymmetric encryption algorithm is what?
A RSA
B
Vigenere
C DES
D Caesar Cipher ANS A - Original, unencrypted information is referred to as .
A text
B plaintext
C cleantext
D ciphertext ANS B
- Which of the following is NOT an asymmetric system?
A PGP
B RSA
C SSL
D DES ANS D - In order for User A to send User B an encrypted message that only
User B can read, User A must encrypt message with which of the following
keys?
A User A’s public key
B User A’s private
key C User B’s public
key
D User B’s private key ANS C - The greatest
weakness with symmetric algorithms is .
A They are less secure than asymmetric
B The problem of key exchange
C They are slower than asymmetric
D The problem of generating keys
ANS B
- Which of the following is generally true about block sizes?
A Smaller block sizes increase security
B Block sizes must be more than 256 bits to be
secure C Block size is irrelevant to security
D Larger block sizes increase security ANS D - A is a function that takes a variable-size input m and
returns a fixed-size string.
A Symmetric cipher
B Hash
C Asymmetric cipher
D Feistel ANS B - Which of the following is a cryptographic protocol that allows two
parties to establish a shared key over an insecure channel?
A Elliptic Curve
B RSA
C MD5
D Diffie-Hellman ANS D - Ais a digital representation of information that identifies
you as a relevant entity by a trusted third party?
A Digital Signature
B Hash
C Ownership
stamp D Digest
ANS A
11.What is the standard used by most digital certificates?
A X.509
B CRL
C RFC 2298
D OCSP
ANS A
12.DES uses keys of what size?