WGU D830 INTRODUCTION TO CRYPTOGRAPHY OA
(OBJECTIVE ASSESSMENT) QUESTIONS AND CORRECT
ANSWERS WITH RATIONALES NEW 2026-2027 UPDATE
99 QUESTIONS
TABLE OF CONTENTS
# TOPIC
1 Analyze and evaluate symmetric and asymmetric cryptographic algorithms for security and performance
2 Apply cryptographic primitives to design secure communication and authentication protocols
3 Assess cryptographic implementations against modern threats and standards
4 WGU D830 Introduction to Cryptography OA
5 Objective Assessment
6 Questions and Correct Answers with Rationales New 2026
7 2027 Update
8 Foundations of Cryptography and Information Security
9 Applied Cryptography and Information Security
10 Advanced Cryptography and Information Security
11 Cryptography and Information Security Review
ABSTRACT
This study document brings together 99 carefully worded exam questions drawn from WGU D830
Introduction to Cryptography OA (Objective Assessment) Questions and Correct Answers with
Rationales New 2026-2027 Update, with the strongest emphasis placed on Analyze and evaluate
symmetric and asymmetric cryptographic algorithms for security and performance, Apply
cryptographic primitives to design secure communication and authentication protocols and Assess
cryptographic implementations against modern threats and standards. 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 EVALUATE SYMMETRIC AND ASYMMETRIC CRYPTOGRAPHIC
ALGORITHMS FOR SECURITY AND PERFORMANCE
In a hybrid cryptosystem, a sender encrypts a message with AES-256-GCM using a
randomly generated session key, then encrypts the session key with RSA-OAEP.
Which security property is primarily ensured by using a random session key
instead of a fixed key?
A. Perfect forward secrecy
B. Semantic security under key reuse CORRECT
C. Non-repudiation of the message
D. Integrity of the session key
RATIONALE: Random session keys ensure that even if one session key is compromised, past or
future sessions remain secure, providing semantic security. Perfect forward secrecy requires
ephemeral key exchange, non-repudiation needs digital signatures, and integrity of the session
key is provided by OAEP, not randomness.
Q2 ANALYZE AND EVALUATE SYMMETRIC AND ASYMMETRIC CRYPTOGRAPHIC
ALGORITHMS FOR SECURITY AND PERFORMANCE
A developer implements SHA-256 for password hashing without salt. An attacker
obtains the hash database and uses a rainbow table. Which countermeasure most
effectively mitigates this attack while maintaining compatibility with existing
systems?
A. Increase the number of hash iterations
B. Use a unique random salt per password CORRECT
C. Switch to SHA-512
D. Encrypt the hash database with AES-256
RATIONALE: A unique random salt per password prevents rainbow table attacks by ensuring
identical passwords produce different hashes. Increasing iterations slows brute-force but doesn't
stop precomputed tables; SHA-512 is still vulnerable without salt; encrypting the database adds a
layer but doesn't address the hashing weakness.
Page 2
,Q3 ANALYZE AND EVALUATE SYMMETRIC AND ASYMMETRIC CRYPTOGRAPHIC
ALGORITHMS FOR SECURITY AND PERFORMANCE
In a Diffie-Hellman key exchange over an elliptic curve, an attacker performs a
small subgroup attack by sending a point of small order. Which validation step
prevents this attack?
A. Verifying that the point lies on the curve
B. Checking that the point is not the identity element
C. Ensuring the point has the correct order
D. Confirming the point is in the prime-order subgroup CORRECT
RATIONALE: Small subgroup attacks are prevented by validating that the received point is in the
prime-order subgroup, typically by checking that it satisfies the subgroup membership test.
Checking only curve membership or identity is insufficient, and order verification is part of
subgroup validation.
Q4 ANALYZE AND EVALUATE SYMMETRIC AND ASYMMETRIC CRYPTOGRAPHIC
ALGORITHMS FOR SECURITY AND PERFORMANCE
A digital signature scheme uses RSA with PKCS#1 v1.5 padding. A researcher
demonstrates a Bleichenbacher-style attack. Which modification to the padding
scheme best mitigates this class of attack?
A. Use RSA-PSS with a random salt CORRECT
B. Increase the RSA key size to 4096 bits
C. Hash the message twice before signing
D. Switch to RSA-OAEP
RATIONALE: RSA-PSS is provably secure and randomized, preventing Bleichenbacher-style
attacks that exploit deterministic PKCS#1 v1.5 padding. Larger keys do not fix padding flaws,
double hashing is non-standard, and OAEP is for encryption, not signatures.
Page 3
, Q5 ANALYZE AND EVALUATE SYMMETRIC AND ASYMMETRIC CRYPTOGRAPHIC
ALGORITHMS FOR SECURITY AND PERFORMANCE
A TLS 1.3 session uses X25519 for key exchange and AES-128-GCM for record
encryption. An attacker records the entire session and later compromises the
server's long-term private key. Which property prevents decryption of the recorded
session?
A. Perfect forward secrecy CORRECT
B. Authenticated encryption
C. Key derivation function
D. Certificate pinning
RATIONALE: Perfect forward secrecy ensures that compromise of long-term keys does not
compromise past session keys, as ephemeral keys are used and discarded. Authenticated
encryption ensures integrity, KDF derives keys, and certificate pinning prevents MITM but not
decryption.
Q6 ANALYZE AND EVALUATE SYMMETRIC AND ASYMMETRIC CRYPTOGRAPHIC
ALGORITHMS FOR SECURITY AND PERFORMANCE
In a blockchain using ECDSA with secp256k1, a developer reuses the same nonce
for two different signatures. What is the immediate consequence?
A. The private key can be recovered CORRECT
B. The signatures become invalid
C. The public key is revealed
D. The transaction is rejected
RATIONALE: Nonce reuse in ECDSA allows an attacker to solve for the private key using two
signatures and the known nonce. The signatures remain valid, the public key is already known,
and the transaction may still be accepted, but security is compromised.
Page 4
(OBJECTIVE ASSESSMENT) QUESTIONS AND CORRECT
ANSWERS WITH RATIONALES NEW 2026-2027 UPDATE
99 QUESTIONS
TABLE OF CONTENTS
# TOPIC
1 Analyze and evaluate symmetric and asymmetric cryptographic algorithms for security and performance
2 Apply cryptographic primitives to design secure communication and authentication protocols
3 Assess cryptographic implementations against modern threats and standards
4 WGU D830 Introduction to Cryptography OA
5 Objective Assessment
6 Questions and Correct Answers with Rationales New 2026
7 2027 Update
8 Foundations of Cryptography and Information Security
9 Applied Cryptography and Information Security
10 Advanced Cryptography and Information Security
11 Cryptography and Information Security Review
ABSTRACT
This study document brings together 99 carefully worded exam questions drawn from WGU D830
Introduction to Cryptography OA (Objective Assessment) Questions and Correct Answers with
Rationales New 2026-2027 Update, with the strongest emphasis placed on Analyze and evaluate
symmetric and asymmetric cryptographic algorithms for security and performance, Apply
cryptographic primitives to design secure communication and authentication protocols and Assess
cryptographic implementations against modern threats and standards. 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 EVALUATE SYMMETRIC AND ASYMMETRIC CRYPTOGRAPHIC
ALGORITHMS FOR SECURITY AND PERFORMANCE
In a hybrid cryptosystem, a sender encrypts a message with AES-256-GCM using a
randomly generated session key, then encrypts the session key with RSA-OAEP.
Which security property is primarily ensured by using a random session key
instead of a fixed key?
A. Perfect forward secrecy
B. Semantic security under key reuse CORRECT
C. Non-repudiation of the message
D. Integrity of the session key
RATIONALE: Random session keys ensure that even if one session key is compromised, past or
future sessions remain secure, providing semantic security. Perfect forward secrecy requires
ephemeral key exchange, non-repudiation needs digital signatures, and integrity of the session
key is provided by OAEP, not randomness.
Q2 ANALYZE AND EVALUATE SYMMETRIC AND ASYMMETRIC CRYPTOGRAPHIC
ALGORITHMS FOR SECURITY AND PERFORMANCE
A developer implements SHA-256 for password hashing without salt. An attacker
obtains the hash database and uses a rainbow table. Which countermeasure most
effectively mitigates this attack while maintaining compatibility with existing
systems?
A. Increase the number of hash iterations
B. Use a unique random salt per password CORRECT
C. Switch to SHA-512
D. Encrypt the hash database with AES-256
RATIONALE: A unique random salt per password prevents rainbow table attacks by ensuring
identical passwords produce different hashes. Increasing iterations slows brute-force but doesn't
stop precomputed tables; SHA-512 is still vulnerable without salt; encrypting the database adds a
layer but doesn't address the hashing weakness.
Page 2
,Q3 ANALYZE AND EVALUATE SYMMETRIC AND ASYMMETRIC CRYPTOGRAPHIC
ALGORITHMS FOR SECURITY AND PERFORMANCE
In a Diffie-Hellman key exchange over an elliptic curve, an attacker performs a
small subgroup attack by sending a point of small order. Which validation step
prevents this attack?
A. Verifying that the point lies on the curve
B. Checking that the point is not the identity element
C. Ensuring the point has the correct order
D. Confirming the point is in the prime-order subgroup CORRECT
RATIONALE: Small subgroup attacks are prevented by validating that the received point is in the
prime-order subgroup, typically by checking that it satisfies the subgroup membership test.
Checking only curve membership or identity is insufficient, and order verification is part of
subgroup validation.
Q4 ANALYZE AND EVALUATE SYMMETRIC AND ASYMMETRIC CRYPTOGRAPHIC
ALGORITHMS FOR SECURITY AND PERFORMANCE
A digital signature scheme uses RSA with PKCS#1 v1.5 padding. A researcher
demonstrates a Bleichenbacher-style attack. Which modification to the padding
scheme best mitigates this class of attack?
A. Use RSA-PSS with a random salt CORRECT
B. Increase the RSA key size to 4096 bits
C. Hash the message twice before signing
D. Switch to RSA-OAEP
RATIONALE: RSA-PSS is provably secure and randomized, preventing Bleichenbacher-style
attacks that exploit deterministic PKCS#1 v1.5 padding. Larger keys do not fix padding flaws,
double hashing is non-standard, and OAEP is for encryption, not signatures.
Page 3
, Q5 ANALYZE AND EVALUATE SYMMETRIC AND ASYMMETRIC CRYPTOGRAPHIC
ALGORITHMS FOR SECURITY AND PERFORMANCE
A TLS 1.3 session uses X25519 for key exchange and AES-128-GCM for record
encryption. An attacker records the entire session and later compromises the
server's long-term private key. Which property prevents decryption of the recorded
session?
A. Perfect forward secrecy CORRECT
B. Authenticated encryption
C. Key derivation function
D. Certificate pinning
RATIONALE: Perfect forward secrecy ensures that compromise of long-term keys does not
compromise past session keys, as ephemeral keys are used and discarded. Authenticated
encryption ensures integrity, KDF derives keys, and certificate pinning prevents MITM but not
decryption.
Q6 ANALYZE AND EVALUATE SYMMETRIC AND ASYMMETRIC CRYPTOGRAPHIC
ALGORITHMS FOR SECURITY AND PERFORMANCE
In a blockchain using ECDSA with secp256k1, a developer reuses the same nonce
for two different signatures. What is the immediate consequence?
A. The private key can be recovered CORRECT
B. The signatures become invalid
C. The public key is revealed
D. The transaction is rejected
RATIONALE: Nonce reuse in ECDSA allows an attacker to solve for the private key using two
signatures and the known nonce. The signatures remain valid, the public key is already known,
and the transaction may still be accepted, but security is compromised.
Page 4
