WGU D830 INTRODUCTION TO CRYPTOGRAPHY
PA QUESTIONS AND CORRECT ANSWERS WITH
RATIONALES NEW 2026-2027 UPDATE
49 QUESTIONS
TABLE OF CONTENTS
# TOPIC
1 Analyze and differentiate symmetric and asymmetric cryptographic algorithms based on security
properties, performance, and use cases
2 Evaluate the security of cryptographic protocols and identify vulnerabilities such as man-in-the-middle,
replay, and padding oracle attacks
3 Apply appropriate cryptographic primitives to design secure systems, including key exchange, digital
signatures, and certificate management
4 Interpret and implement cryptographic standards (e
5 WGU D830 Introduction to Cryptography PA Questions and Correct Answers with Rationales New 2026
6 2027 Update
7 Foundations of Cryptography and Information Security
8 Applied Cryptography and Information Security
9 Advanced Cryptography and Information Security
10 Cryptography and Information Security Review
ABSTRACT
This study document brings together 49 carefully worded exam questions drawn from WGU D830
Introduction to Cryptography PA Questions and Correct Answers with Rationales New 2026-2027
Update, with the strongest emphasis placed on Analyze and differentiate symmetric and
asymmetric cryptographic algorithms based on security properties, performance, and use cases,
Evaluate the security of cryptographic protocols and identify vulnerabilities such as
man-in-the-middle, replay, and padding oracle attacks, Apply appropriate cryptographic primitives
to design secure systems, including key exchange, digital signatures and and certificate
management. Every item follows the wording style and level of reasoning you meet in the real
paper, and each one is paired with a clear rationale so the correct choice is never a guess. Work
through the set at your own pace, mark the questions that slow you down, then come back to them
until the reasoning feels automatic. Learners who revise this way walk into the exam room
recognising the pattern behind the questions instead of meeting them for the first time. Keep going
- steady, honest practice is what turns a difficult paper into a comfortable pass.
Page 1
,Q1 ANALYZE AND DIFFERENTIATE SYMMETRIC AND ASYMMETRIC CRYPTOGRAPHIC
ALGORITHMS BASED ON SECURITY PROPERTIES, PERFORMANCE, AND USE CASES
In a hybrid cryptosystem, a sender encrypts a random symmetric key with the
recipient's RSA public key and then encrypts the message with AES-GCM. Which
security property is most directly compromised if the RSA encryption uses
PKCS#1 v1.5 padding without randomizing the padding?
A. Confidentiality of the symmetric key due to deterministic encryption CORRECT
B. Integrity of the AES-GCM ciphertext
C. Authentication of the sender's identity
D. Forward secrecy of the session key
RATIONALE: PKCS#1 v1.5 padding without randomization makes RSA encryption deterministic,
allowing an attacker to test guesses of the symmetric key by encrypting candidate keys and
comparing ciphertexts. This compromises confidentiality of the symmetric key. Integrity of
AES-GCM is independent, sender authentication requires signatures, and forward secrecy is not
provided by RSA key transport.
Q2 ANALYZE AND DIFFERENTIATE SYMMETRIC AND ASYMMETRIC CRYPTOGRAPHIC
ALGORITHMS BASED ON SECURITY PROPERTIES, PERFORMANCE, AND USE CASES
A developer proposes using SHA-256 in a construction where the hash of a
message is XORed with a secret key to produce a MAC (i.e., MAC = H(message)
K). Which cryptographic weakness does this construction exhibit?
A. Length extension attack
B. Key recovery via known plaintext CORRECT
C. Collision resistance failure
D. Timing side-channel
RATIONALE: XORing the hash with a secret key is vulnerable to key recovery: if an attacker
knows one message and its MAC, they can compute H(message) and then XOR with the MAC to
recover K. Length extension applies to Merkle-Damgård hashes when secret-prefix MACs are
used, not this XOR construction. Collision resistance and timing are not the primary issues here.
Page 2
, Q3 ANALYZE AND DIFFERENTIATE SYMMETRIC AND ASYMMETRIC CRYPTOGRAPHIC
ALGORITHMS BASED ON SECURITY PROPERTIES, PERFORMANCE, AND USE CASES
During a TLS 1.3 handshake, a client and server establish a shared secret using
ECDHE. Which statement best describes how forward secrecy is achieved in this
protocol?
A. The server's long-term private key is used to encrypt the session key.
B. Ephemeral key pairs are generated per session and discarded after use. CORRECT
C. The session key is derived from the client's pre-shared secret.
D. The handshake transcript is hashed with SHA-256 to produce the master secret.
RATIONALE: Forward secrecy in TLS 1.3 is achieved through ephemeral Diffie-Hellman key
exchange, where temporary key pairs are generated for each session and discarded, ensuring
past session keys remain secure even if long-term keys are compromised. Option A describes
RSA key transport, which lacks forward secrecy. Options C and D do not provide forward
secrecy.
Q4 ANALYZE AND DIFFERENTIATE SYMMETRIC AND ASYMMETRIC CRYPTOGRAPHIC
ALGORITHMS BASED ON SECURITY PROPERTIES, PERFORMANCE, AND USE CASES
A security architect must choose a digital signature algorithm for a system
requiring long-term security and resistance to quantum computers. Which of the
following is currently standardized by NIST for post-quantum digital signatures?
A. RSA-PSS with 3072-bit keys
B. ECDSA with secp256r1
C. CRYSTALS-Dilithium CORRECT
D. Ed25519
RATIONALE: CRYSTALS-Dilithium is a NIST-standardized post-quantum digital signature
algorithm (selected in 2022 and standardized in 2024). RSA, ECDSA, and Ed25519 are classical
algorithms vulnerable to quantum attacks via Shor's algorithm. Thus, only Dilithium offers
quantum resistance.
Page 3
PA QUESTIONS AND CORRECT ANSWERS WITH
RATIONALES NEW 2026-2027 UPDATE
49 QUESTIONS
TABLE OF CONTENTS
# TOPIC
1 Analyze and differentiate symmetric and asymmetric cryptographic algorithms based on security
properties, performance, and use cases
2 Evaluate the security of cryptographic protocols and identify vulnerabilities such as man-in-the-middle,
replay, and padding oracle attacks
3 Apply appropriate cryptographic primitives to design secure systems, including key exchange, digital
signatures, and certificate management
4 Interpret and implement cryptographic standards (e
5 WGU D830 Introduction to Cryptography PA Questions and Correct Answers with Rationales New 2026
6 2027 Update
7 Foundations of Cryptography and Information Security
8 Applied Cryptography and Information Security
9 Advanced Cryptography and Information Security
10 Cryptography and Information Security Review
ABSTRACT
This study document brings together 49 carefully worded exam questions drawn from WGU D830
Introduction to Cryptography PA Questions and Correct Answers with Rationales New 2026-2027
Update, with the strongest emphasis placed on Analyze and differentiate symmetric and
asymmetric cryptographic algorithms based on security properties, performance, and use cases,
Evaluate the security of cryptographic protocols and identify vulnerabilities such as
man-in-the-middle, replay, and padding oracle attacks, Apply appropriate cryptographic primitives
to design secure systems, including key exchange, digital signatures and and certificate
management. Every item follows the wording style and level of reasoning you meet in the real
paper, and each one is paired with a clear rationale so the correct choice is never a guess. Work
through the set at your own pace, mark the questions that slow you down, then come back to them
until the reasoning feels automatic. Learners who revise this way walk into the exam room
recognising the pattern behind the questions instead of meeting them for the first time. Keep going
- steady, honest practice is what turns a difficult paper into a comfortable pass.
Page 1
,Q1 ANALYZE AND DIFFERENTIATE SYMMETRIC AND ASYMMETRIC CRYPTOGRAPHIC
ALGORITHMS BASED ON SECURITY PROPERTIES, PERFORMANCE, AND USE CASES
In a hybrid cryptosystem, a sender encrypts a random symmetric key with the
recipient's RSA public key and then encrypts the message with AES-GCM. Which
security property is most directly compromised if the RSA encryption uses
PKCS#1 v1.5 padding without randomizing the padding?
A. Confidentiality of the symmetric key due to deterministic encryption CORRECT
B. Integrity of the AES-GCM ciphertext
C. Authentication of the sender's identity
D. Forward secrecy of the session key
RATIONALE: PKCS#1 v1.5 padding without randomization makes RSA encryption deterministic,
allowing an attacker to test guesses of the symmetric key by encrypting candidate keys and
comparing ciphertexts. This compromises confidentiality of the symmetric key. Integrity of
AES-GCM is independent, sender authentication requires signatures, and forward secrecy is not
provided by RSA key transport.
Q2 ANALYZE AND DIFFERENTIATE SYMMETRIC AND ASYMMETRIC CRYPTOGRAPHIC
ALGORITHMS BASED ON SECURITY PROPERTIES, PERFORMANCE, AND USE CASES
A developer proposes using SHA-256 in a construction where the hash of a
message is XORed with a secret key to produce a MAC (i.e., MAC = H(message)
K). Which cryptographic weakness does this construction exhibit?
A. Length extension attack
B. Key recovery via known plaintext CORRECT
C. Collision resistance failure
D. Timing side-channel
RATIONALE: XORing the hash with a secret key is vulnerable to key recovery: if an attacker
knows one message and its MAC, they can compute H(message) and then XOR with the MAC to
recover K. Length extension applies to Merkle-Damgård hashes when secret-prefix MACs are
used, not this XOR construction. Collision resistance and timing are not the primary issues here.
Page 2
, Q3 ANALYZE AND DIFFERENTIATE SYMMETRIC AND ASYMMETRIC CRYPTOGRAPHIC
ALGORITHMS BASED ON SECURITY PROPERTIES, PERFORMANCE, AND USE CASES
During a TLS 1.3 handshake, a client and server establish a shared secret using
ECDHE. Which statement best describes how forward secrecy is achieved in this
protocol?
A. The server's long-term private key is used to encrypt the session key.
B. Ephemeral key pairs are generated per session and discarded after use. CORRECT
C. The session key is derived from the client's pre-shared secret.
D. The handshake transcript is hashed with SHA-256 to produce the master secret.
RATIONALE: Forward secrecy in TLS 1.3 is achieved through ephemeral Diffie-Hellman key
exchange, where temporary key pairs are generated for each session and discarded, ensuring
past session keys remain secure even if long-term keys are compromised. Option A describes
RSA key transport, which lacks forward secrecy. Options C and D do not provide forward
secrecy.
Q4 ANALYZE AND DIFFERENTIATE SYMMETRIC AND ASYMMETRIC CRYPTOGRAPHIC
ALGORITHMS BASED ON SECURITY PROPERTIES, PERFORMANCE, AND USE CASES
A security architect must choose a digital signature algorithm for a system
requiring long-term security and resistance to quantum computers. Which of the
following is currently standardized by NIST for post-quantum digital signatures?
A. RSA-PSS with 3072-bit keys
B. ECDSA with secp256r1
C. CRYSTALS-Dilithium CORRECT
D. Ed25519
RATIONALE: CRYSTALS-Dilithium is a NIST-standardized post-quantum digital signature
algorithm (selected in 2022 and standardized in 2024). RSA, ECDSA, and Ed25519 are classical
algorithms vulnerable to quantum attacks via Shor's algorithm. Thus, only Dilithium offers
quantum resistance.
Page 3
