Page 1 of 29
WGU C839 OBJECTIVE ASSESSMENT (VERSION A & B) |
WGU C839 INTRODUCTION TO CRYPTOGRAPHY OA
ACTUAL EXAM QUESTIONS AND CORRECT ANSWERS |
LATEST UPDATE 2026/2027 | GUARANTEED PASS.
Which encryption standard uses the same key to encrypt and decrypt
messages?
Symmetric
Which algorithm is designated as a Type 2 product by the National
Security Agency (NSA)?
Skipjack
What is the most commonly used format for certificates?
X.509 v3
What is referenced to determine if a certificate has been revoked?
Certificate revocation list (CRL)
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What needs to be installed on end users' computers to allow them to trust
applications that have been digitally signed by the developer?
Sender's public key
Which algorithm implements an unbalanced Feistel cipher?
Skipjack
With Cipher-block chaining (CBC) what happens?
Each block of plaintext is XORed with the previous ciphertext block
before being encrypted
With Cipher feedback (CFB) what happens?
The ciphertext block is encrypted then the ciphertext produced is XOR'd
back with the plaintext to produce the current ciphertext block.
What does Output feedback (OFB) do?
, Page 3 of 29
A block cipher is converted into a stream cipher by generating a
keystream blocks, which are then XORed with the plaintext blocks to
get the ciphertext
With Electronic codebook (ECB) what happens
The message is divided into blocks and each block is encrypted
separately. This is the most basic mode for symmetric encryption.
What modes cannot be used to turn a block cipher into a stream cipher?
(select 2)
CTR/OFB
What is an initialization vector (IV)?
A fixed size random stream that is added to a block cipher to increase
randomness.
A number that is used only one time, then discarded is called what?
Nonce
What is the largest key size that RC4 can use?
256 bits
WGU C839 OBJECTIVE ASSESSMENT (VERSION A & B) |
WGU C839 INTRODUCTION TO CRYPTOGRAPHY OA
ACTUAL EXAM QUESTIONS AND CORRECT ANSWERS |
LATEST UPDATE 2026/2027 | GUARANTEED PASS.
Which encryption standard uses the same key to encrypt and decrypt
messages?
Symmetric
Which algorithm is designated as a Type 2 product by the National
Security Agency (NSA)?
Skipjack
What is the most commonly used format for certificates?
X.509 v3
What is referenced to determine if a certificate has been revoked?
Certificate revocation list (CRL)
,Page 2 of 29
What needs to be installed on end users' computers to allow them to trust
applications that have been digitally signed by the developer?
Sender's public key
Which algorithm implements an unbalanced Feistel cipher?
Skipjack
With Cipher-block chaining (CBC) what happens?
Each block of plaintext is XORed with the previous ciphertext block
before being encrypted
With Cipher feedback (CFB) what happens?
The ciphertext block is encrypted then the ciphertext produced is XOR'd
back with the plaintext to produce the current ciphertext block.
What does Output feedback (OFB) do?
, Page 3 of 29
A block cipher is converted into a stream cipher by generating a
keystream blocks, which are then XORed with the plaintext blocks to
get the ciphertext
With Electronic codebook (ECB) what happens
The message is divided into blocks and each block is encrypted
separately. This is the most basic mode for symmetric encryption.
What modes cannot be used to turn a block cipher into a stream cipher?
(select 2)
CTR/OFB
What is an initialization vector (IV)?
A fixed size random stream that is added to a block cipher to increase
randomness.
A number that is used only one time, then discarded is called what?
Nonce
What is the largest key size that RC4 can use?
256 bits
