WGU Course C839 - Intro to Cryptography with Complete Solutions
What type of encryption uses different keys B User A's private key
to encrypt and decrypt the message? C User B's public key
D User B's private key - ANSWER -C
A Symmetric
B Private key
C Secure The greatest weakness with symmetric
D Asymmetric - ANSWER -D algorithms is _____.
A They are less secure than asymmetric
The most widely used asymmetric encryption B The problem of key exchange
algorithm is what? C They are slower than asymmetric
D The problem of generating keys -
A RSA ANSWER -B
B Vigenere
C DES
D Caesar Cipher - ANSWER -A Which of the following is generally true about
block sizes?
Original, unencrypted information is referred A Smaller block sizes increase security
to as ____. B Block sizes must be more than 256 bits to
be secure
A text C Block size is irrelevant to security
B plaintext D Larger block sizes increase security -
C cleantext ANSWER -D
D ciphertext - ANSWER -B
A _____ is a function that takes a variable-size
Which of the following is NOT an asymmetric input m and returns a fixed-size string.
system?
A Symmetric cipher
A PGP B Hash
B RSA C Asymmetric cipher
C SSL D Feistel - ANSWER -B
D DES - ANSWER -D
Which of the following is a cryptographic
In order for User A to send User B an protocol that allows two parties to establish a
encrypted message that only User B can shared key over an insecure channel?
read, User A must encrypt message with
which of the following keys? A Elliptic Curve
B RSA
A User A's public key C MD5
, WGU Course C839 - Intro to Cryptography with Complete Solutions
D Diffie-Hellman - ANSWER -D
A Vigenere
B Caesar
A _________ is a digital representation of C Atbash
information that identifies you as a relevant D Scytale - ANSWER -A
entity by a trusted third party?
A Digital Signature Which of the following is a substitution cipher
B Hash used by ancient Hebrew scholars?
C Ownership stamp
D Digest - ANSWER -A A Caesar
B Vigenere
C Scytale
What is the standard used by most digital D Atbash - ANSWER -D
certificates?
A X.509 Shifting each letter in the alphabet a fixed
B CRL number of spaces to the right or left is an
C RFC 2298 example of what?
D OCSP - ANSWER -A
A Bit shifting
B Confusion
DES uses keys of what size? C Multi substitution
D Single substitution - ANSWER -D
A 56 bits
B 192 bits
C 128 bits Which of the following most accurately
D 64 bits - ANSWER -A defines encryption?
A changing a message so it can only be easily
Which of the following is NOT a key size used read by the intended recipient
by AES?
B Making binary changes to a message to
A 512 bits conceal it
B 128 bits
C 192 bits C changing a message using complex
D 256 bits - ANSWER -A mathematics
D Applying keys to plain text -
Which of the following was a multi alphabet ANSWER -A
cipher widely used from the 16th century
(1553) to the early 20th century (1900s)?
, WGU Course C839 - Intro to Cryptography with Complete Solutions
If you use substitution alone, what weakness
is present in the resulting cipher text? A Electronic codebook (ECB)
B Cipher-block chaining (CBC)
A It is the same length as the original text C Cipher feedback (CFB)
B It is easily broken with modern computers. D Output feedback (OFB) - ANSWER -A
C It is too simple.
D Because it maintains letter and word
frequency. - ANSWER -D Which of the following is an example of an
unbalanced Feistel?
_____ uses at least two different shifts, A 3DES
changing the shift with different letters in the B Skipjack
plain text. C Twofish
D AES - ANSWER -B
A Atbash
B multi-alphabet encryption
C Scytale This process is done by having each block of
D Caesar cipher - ANSWER -B plaintext is XORed with the previous
ciphertext block before being encrypted.
____ was designed to provide built in A Output feedback (OFB)
cryptography for the clipper chip. B Cipher-block chaining (CBC)
C Electronic codebook (ECB)
A Blowfish D Cipher feedback (CFB) - ANSWER -B
B Skipjack
C GOST
D 3DES - ANSWER -B The process wherein the ciphertext block is
encrypted then the ciphertext produced is
XOR'd back with the plaintext to produce the
Which of the following uses an 80 bit key on current ciphertext block is called what?
64 bit blocks?
A Output feedback (OFB)
A Twofish B Cipher-block chaining (CBC)
B AES C Cipher feedback (CFB)
C Skipjack D Electronic codebook (ECB) -
D DES - ANSWER -C ANSWER -C
With _____, the message is divided into This is a method for turning a block cipher
blocks and each block is encrypted into a stream cipher by generating a
separately. This is the most basic mode for keystream block, which are then XORed with
symmetric encryption. the plaintext blocks to get the ciphertext.
What type of encryption uses different keys B User A's private key
to encrypt and decrypt the message? C User B's public key
D User B's private key - ANSWER -C
A Symmetric
B Private key
C Secure The greatest weakness with symmetric
D Asymmetric - ANSWER -D algorithms is _____.
A They are less secure than asymmetric
The most widely used asymmetric encryption B The problem of key exchange
algorithm is what? C They are slower than asymmetric
D The problem of generating keys -
A RSA ANSWER -B
B Vigenere
C DES
D Caesar Cipher - ANSWER -A Which of the following is generally true about
block sizes?
Original, unencrypted information is referred A Smaller block sizes increase security
to as ____. B Block sizes must be more than 256 bits to
be secure
A text C Block size is irrelevant to security
B plaintext D Larger block sizes increase security -
C cleantext ANSWER -D
D ciphertext - ANSWER -B
A _____ is a function that takes a variable-size
Which of the following is NOT an asymmetric input m and returns a fixed-size string.
system?
A Symmetric cipher
A PGP B Hash
B RSA C Asymmetric cipher
C SSL D Feistel - ANSWER -B
D DES - ANSWER -D
Which of the following is a cryptographic
In order for User A to send User B an protocol that allows two parties to establish a
encrypted message that only User B can shared key over an insecure channel?
read, User A must encrypt message with
which of the following keys? A Elliptic Curve
B RSA
A User A's public key C MD5
, WGU Course C839 - Intro to Cryptography with Complete Solutions
D Diffie-Hellman - ANSWER -D
A Vigenere
B Caesar
A _________ is a digital representation of C Atbash
information that identifies you as a relevant D Scytale - ANSWER -A
entity by a trusted third party?
A Digital Signature Which of the following is a substitution cipher
B Hash used by ancient Hebrew scholars?
C Ownership stamp
D Digest - ANSWER -A A Caesar
B Vigenere
C Scytale
What is the standard used by most digital D Atbash - ANSWER -D
certificates?
A X.509 Shifting each letter in the alphabet a fixed
B CRL number of spaces to the right or left is an
C RFC 2298 example of what?
D OCSP - ANSWER -A
A Bit shifting
B Confusion
DES uses keys of what size? C Multi substitution
D Single substitution - ANSWER -D
A 56 bits
B 192 bits
C 128 bits Which of the following most accurately
D 64 bits - ANSWER -A defines encryption?
A changing a message so it can only be easily
Which of the following is NOT a key size used read by the intended recipient
by AES?
B Making binary changes to a message to
A 512 bits conceal it
B 128 bits
C 192 bits C changing a message using complex
D 256 bits - ANSWER -A mathematics
D Applying keys to plain text -
Which of the following was a multi alphabet ANSWER -A
cipher widely used from the 16th century
(1553) to the early 20th century (1900s)?
, WGU Course C839 - Intro to Cryptography with Complete Solutions
If you use substitution alone, what weakness
is present in the resulting cipher text? A Electronic codebook (ECB)
B Cipher-block chaining (CBC)
A It is the same length as the original text C Cipher feedback (CFB)
B It is easily broken with modern computers. D Output feedback (OFB) - ANSWER -A
C It is too simple.
D Because it maintains letter and word
frequency. - ANSWER -D Which of the following is an example of an
unbalanced Feistel?
_____ uses at least two different shifts, A 3DES
changing the shift with different letters in the B Skipjack
plain text. C Twofish
D AES - ANSWER -B
A Atbash
B multi-alphabet encryption
C Scytale This process is done by having each block of
D Caesar cipher - ANSWER -B plaintext is XORed with the previous
ciphertext block before being encrypted.
____ was designed to provide built in A Output feedback (OFB)
cryptography for the clipper chip. B Cipher-block chaining (CBC)
C Electronic codebook (ECB)
A Blowfish D Cipher feedback (CFB) - ANSWER -B
B Skipjack
C GOST
D 3DES - ANSWER -B The process wherein the ciphertext block is
encrypted then the ciphertext produced is
XOR'd back with the plaintext to produce the
Which of the following uses an 80 bit key on current ciphertext block is called what?
64 bit blocks?
A Output feedback (OFB)
A Twofish B Cipher-block chaining (CBC)
B AES C Cipher feedback (CFB)
C Skipjack D Electronic codebook (ECB) -
D DES - ANSWER -C ANSWER -C
With _____, the message is divided into This is a method for turning a block cipher
blocks and each block is encrypted into a stream cipher by generating a
separately. This is the most basic mode for keystream block, which are then XORed with
symmetric encryption. the plaintext blocks to get the ciphertext.
