(2) HNO1 Intro to Cryptography WGU
D334 OA Objective Assessment Due 28th
March Complete Actual Exam Questions
6 - 60 Screenshots D334 Introduction to
Cryptography WGU HNO1 D334 OA.pdf
,Exam Overview
The D334 OA covers core cryptography concepts including encryption and decryption
methods, symmetric and asymmetric cryptography, hashing algorithms, digital
signatures, public key infrastructure (PKI), key exchange protocols, and basic
cryptographic applications in cybersecurity.
SECTION 1: FOUNDATIONAL PRINCIPLES & CLASSICAL
CRYPTOGRAPHY (Questions 1-15)
Question 1
According to Kerckhoffs's Principle, what should the security of a cryptosystem depend
on?
A) The secrecy of the encryption algorithm
B) The complexity of the mathematics
C) The secrecy of the key
D) The length of the plaintext
Answer: C) The secrecy of the key
Rationale: Kerckhoffs's Principle states that a cryptosystem should be secure even if
everything about the system, except the key, is public. Relying on the secrecy of the
algorithm ("security through obscurity") is a fatal flaw because reverse engineering or
leaks expose the system entirely. The key is the only thing that should remain secret.
,Question 2
Which concept ensures that a single-bit change in the plaintext results in approximately
half of the ciphertext bits changing, thereby hiding statistical patterns?
A) Confusion
B) Diffusion
C) Non-repudiation
D) Collision resistance
Answer: B) Diffusion
Rationale: Shannon identified two methods to thwart cryptanalysis: Confusion (making
the key-ciphertext relationship complex) and Diffusion (spreading the influence of one
plaintext bit over many ciphertext bits). The avalanche effect—where changing one
plaintext bit changes approximately half of the ciphertext bits—is a measure of good
diffusion.
Question 3
Shifting each letter in the alphabet a fixed number of spaces is an example of what type
of cipher?
A) Mono-alphabetic substitution
B) Polyalphabetic substitution
C) Transposition
D) Steganography
Answer: A) Mono-alphabetic substitution
, Rationale: The Caesar cipher uses a single fixed shift value for all letters, making it a
mono-alphabetic (single alphabet) substitution cipher.
Question 4
A cryptanalyst finds a repeated sequence of characters "KXD" in a ciphertext 18
characters apart, and another sequence "LGH" 36 characters apart. Which classical
cryptanalysis technique is being applied?
A) Frequency Analysis
B) Index of Coincidence
C) Kasiski Examination
D) Meet-in-the-Middle
Answer: C) Kasiski Examination
Rationale: The Kasiski Examination looks for repeating strings in the ciphertext to guess
the length of the keyword in polyalphabetic ciphers like the Vigenère cipher. The
greatest common divisor (GCD) of the distances (18, 36) suggests the key length.
Question 5
Why is the One-Time Pad (OTP) considered theoretically unbreakable?
A) It uses complex mathematical formulas
B) The key is truly random, as long as the message, and never reused
C) It uses a public key infrastructure
D) It requires a digital signature
Answer: B) The key is truly random, as long as the message, and never reused
D334 OA Objective Assessment Due 28th
March Complete Actual Exam Questions
6 - 60 Screenshots D334 Introduction to
Cryptography WGU HNO1 D334 OA.pdf
,Exam Overview
The D334 OA covers core cryptography concepts including encryption and decryption
methods, symmetric and asymmetric cryptography, hashing algorithms, digital
signatures, public key infrastructure (PKI), key exchange protocols, and basic
cryptographic applications in cybersecurity.
SECTION 1: FOUNDATIONAL PRINCIPLES & CLASSICAL
CRYPTOGRAPHY (Questions 1-15)
Question 1
According to Kerckhoffs's Principle, what should the security of a cryptosystem depend
on?
A) The secrecy of the encryption algorithm
B) The complexity of the mathematics
C) The secrecy of the key
D) The length of the plaintext
Answer: C) The secrecy of the key
Rationale: Kerckhoffs's Principle states that a cryptosystem should be secure even if
everything about the system, except the key, is public. Relying on the secrecy of the
algorithm ("security through obscurity") is a fatal flaw because reverse engineering or
leaks expose the system entirely. The key is the only thing that should remain secret.
,Question 2
Which concept ensures that a single-bit change in the plaintext results in approximately
half of the ciphertext bits changing, thereby hiding statistical patterns?
A) Confusion
B) Diffusion
C) Non-repudiation
D) Collision resistance
Answer: B) Diffusion
Rationale: Shannon identified two methods to thwart cryptanalysis: Confusion (making
the key-ciphertext relationship complex) and Diffusion (spreading the influence of one
plaintext bit over many ciphertext bits). The avalanche effect—where changing one
plaintext bit changes approximately half of the ciphertext bits—is a measure of good
diffusion.
Question 3
Shifting each letter in the alphabet a fixed number of spaces is an example of what type
of cipher?
A) Mono-alphabetic substitution
B) Polyalphabetic substitution
C) Transposition
D) Steganography
Answer: A) Mono-alphabetic substitution
, Rationale: The Caesar cipher uses a single fixed shift value for all letters, making it a
mono-alphabetic (single alphabet) substitution cipher.
Question 4
A cryptanalyst finds a repeated sequence of characters "KXD" in a ciphertext 18
characters apart, and another sequence "LGH" 36 characters apart. Which classical
cryptanalysis technique is being applied?
A) Frequency Analysis
B) Index of Coincidence
C) Kasiski Examination
D) Meet-in-the-Middle
Answer: C) Kasiski Examination
Rationale: The Kasiski Examination looks for repeating strings in the ciphertext to guess
the length of the keyword in polyalphabetic ciphers like the Vigenère cipher. The
greatest common divisor (GCD) of the distances (18, 36) suggests the key length.
Question 5
Why is the One-Time Pad (OTP) considered theoretically unbreakable?
A) It uses complex mathematical formulas
B) The key is truly random, as long as the message, and never reused
C) It uses a public key infrastructure
D) It requires a digital signature
Answer: B) The key is truly random, as long as the message, and never reused
