2026/2027
WGU D330 Introduction to
Cryptography OA Final Exam Study
Guide 2026/2027: Comprehensive
Review of Encryption,
Cryptographic Protocols, Security
Models, and Practice Questions
Question 1:
A company wants its identity verified by a trusted third-party certificate authority
(CA). Which key is used to sign the certificate issued to the company?
A. Private key of the company
B. Public key of the company
C. Public key of the root CA
D. Private key of the root CA
Correct Answer: D. Private key of the root CA
Rationale:
In Public Key Infrastructure (PKI), certificate authorities (CAs) issue digital
certificates to validate identities. The root CA uses its private key to digitally sign
certificates. This signature ensures authenticity and trust because only the CA
possesses this private key. The company’s public and private keys are used for
encryption and identity verification, but not for signing the certificate itself. The CA’s
public key is distributed to users to verify the signature, not to create it.
Question 2:
Which key should a business send to customers so they can verify encrypted
communications from the business?
A. Private key of the company
B. Public key of the company
C. Private key of the root CA
D. Public key of the root CA
Correct Answer: B. Public key of the company
,2026/2027
Rationale:
In asymmetric cryptography, the public key is shared openly and allows others to
verify signatures or encrypt messages for the owner. Customers use the company’s
public key to validate digital signatures or encrypt data that only the company can
decrypt using its private key. Private keys must remain secret to maintain security,
making them unsuitable for distribution.
Question 3:
Which format is used to import and export certificates and entire chains of trust?
A. CER
B. PKCS #7
C. PKCS #12
D. RTF
Correct Answer: C. PKCS #12
Rationale:
PKCS #12 is a secure format used to store and transfer private keys, certificates, and
full certificate chains in a single encrypted file. CER and PKCS #7 do not include
private keys, making them unsuitable for full trust chains. RTF is unrelated to
cryptography.
Question 4:
Which field in an X.509 certificate contains the hash of the certificate for integrity
verification?
A. Subject
B. Issuer
C. Version
D. Thumbprint
Correct Answer: D. Thumbprint
Rationale:
The thumbprint is a cryptographic hash of the certificate used to ensure integrity. It
allows systems to verify that the certificate has not been altered. The subject identifies
the owner, the issuer identifies the CA, and version defines the certificate format.
Question 5:
Employee B sends an encrypted message to Employee A. What does Employee A use
to decrypt it?
, 2026/2027
A. Employee B’s public key
B. Employee B’s private key
C. Employee A’s private key
D. Employee A’s public key
Correct Answer: C. Employee A’s private key
Rationale:
In asymmetric encryption, data encrypted with a recipient’s public key can only be
decrypted using the recipient’s private key. This ensures confidentiality, as only
Employee A possesses the private key needed to decrypt the message.
Question 6:
Which is an example of a symmetric encryption algorithm?
A. RSA
B. AES
C. SHA
D. MD5
Correct Answer: B. AES
Rationale:
AES (Advanced Encryption Standard) is a symmetric algorithm using the same key
for encryption and decryption. RSA is asymmetric, while SHA and MD5 are hashing
algorithms, not encryption methods.
Question 7:
Which two components must be known to both parties before symmetric encryption is
applied? (Choose two.)
A. Cryptographic algorithm
B. Cryptographic key
C. Plaintext content
D. Initialization vector
E. Nonce value
Correct Answer: A. Cryptographic algorithm and B. Cryptographic key
Rationale:
Both parties must agree on the encryption algorithm and share a secret key
beforehand. The algorithm defines how encryption works, while the key controls the
transformation. Plaintext is the data being encrypted and is not pre-shared. IVs and
nonces enhance randomness but are not strictly required for both parties in all
symmetric systems.
WGU D330 Introduction to
Cryptography OA Final Exam Study
Guide 2026/2027: Comprehensive
Review of Encryption,
Cryptographic Protocols, Security
Models, and Practice Questions
Question 1:
A company wants its identity verified by a trusted third-party certificate authority
(CA). Which key is used to sign the certificate issued to the company?
A. Private key of the company
B. Public key of the company
C. Public key of the root CA
D. Private key of the root CA
Correct Answer: D. Private key of the root CA
Rationale:
In Public Key Infrastructure (PKI), certificate authorities (CAs) issue digital
certificates to validate identities. The root CA uses its private key to digitally sign
certificates. This signature ensures authenticity and trust because only the CA
possesses this private key. The company’s public and private keys are used for
encryption and identity verification, but not for signing the certificate itself. The CA’s
public key is distributed to users to verify the signature, not to create it.
Question 2:
Which key should a business send to customers so they can verify encrypted
communications from the business?
A. Private key of the company
B. Public key of the company
C. Private key of the root CA
D. Public key of the root CA
Correct Answer: B. Public key of the company
,2026/2027
Rationale:
In asymmetric cryptography, the public key is shared openly and allows others to
verify signatures or encrypt messages for the owner. Customers use the company’s
public key to validate digital signatures or encrypt data that only the company can
decrypt using its private key. Private keys must remain secret to maintain security,
making them unsuitable for distribution.
Question 3:
Which format is used to import and export certificates and entire chains of trust?
A. CER
B. PKCS #7
C. PKCS #12
D. RTF
Correct Answer: C. PKCS #12
Rationale:
PKCS #12 is a secure format used to store and transfer private keys, certificates, and
full certificate chains in a single encrypted file. CER and PKCS #7 do not include
private keys, making them unsuitable for full trust chains. RTF is unrelated to
cryptography.
Question 4:
Which field in an X.509 certificate contains the hash of the certificate for integrity
verification?
A. Subject
B. Issuer
C. Version
D. Thumbprint
Correct Answer: D. Thumbprint
Rationale:
The thumbprint is a cryptographic hash of the certificate used to ensure integrity. It
allows systems to verify that the certificate has not been altered. The subject identifies
the owner, the issuer identifies the CA, and version defines the certificate format.
Question 5:
Employee B sends an encrypted message to Employee A. What does Employee A use
to decrypt it?
, 2026/2027
A. Employee B’s public key
B. Employee B’s private key
C. Employee A’s private key
D. Employee A’s public key
Correct Answer: C. Employee A’s private key
Rationale:
In asymmetric encryption, data encrypted with a recipient’s public key can only be
decrypted using the recipient’s private key. This ensures confidentiality, as only
Employee A possesses the private key needed to decrypt the message.
Question 6:
Which is an example of a symmetric encryption algorithm?
A. RSA
B. AES
C. SHA
D. MD5
Correct Answer: B. AES
Rationale:
AES (Advanced Encryption Standard) is a symmetric algorithm using the same key
for encryption and decryption. RSA is asymmetric, while SHA and MD5 are hashing
algorithms, not encryption methods.
Question 7:
Which two components must be known to both parties before symmetric encryption is
applied? (Choose two.)
A. Cryptographic algorithm
B. Cryptographic key
C. Plaintext content
D. Initialization vector
E. Nonce value
Correct Answer: A. Cryptographic algorithm and B. Cryptographic key
Rationale:
Both parties must agree on the encryption algorithm and share a secret key
beforehand. The algorithm defines how encryption works, while the key controls the
transformation. Plaintext is the data being encrypted and is not pre-shared. IVs and
nonces enhance randomness but are not strictly required for both parties in all
symmetric systems.
