WGU COURSE C839 INTRO TO
CRYPTOGRAPHY 2024 PROCTORED EXAM
QUESTIONS WITH DETAILED VERIFIED
SOLUTIONS AND RATIONALE /A+ GRADE
ASSURED
What type of encryption uses different keys to encrypt and decrypt the message?
A Symmetric
B Private key
C Secure
D Asymmetric - Answer D
The most widely used asymmetric encryption algorithm is what?
A RSA
B Vigenere
C DES
D Caesar Cipher - Answer A
Original, unencrypted information is referred to as ____.
A text
B plaintext
C cleantext
D ciphertext - Answer B
Which of the following is NOT an asymmetric system?
A PGP
B RSA
C SSL
D DES - Answer D
In order for User A to send User B an encrypted message that only User B can read,
User A must encrypt message with which of the following keys?
A User A's public key
B User A's private key
C User B's public key
D User B's private key - Answer C
,The greatest weakness with symmetric algorithms is _____.
A They are less secure than asymmetric
B The problem of key exchange
C They are slower than asymmetric
D The problem of generating keys - Answer B
Which of the following is generally true about block sizes?
A Smaller block sizes increase security
B Block sizes must be more than 256 bits to be secure
C Block size is irrelevant to security
D Larger block sizes increase security - Answer D
A _____ is a function that takes a variable-size input m and returns a fixed-size string.
A Symmetric cipher
B Hash
C Asymmetric cipher
D Feistel - Answer B
Which of the following is a cryptographic protocol that allows two parties to establish a
shared key over an insecure channel?
A Elliptic Curve
B RSA
C MD5
D Diffie-Hellman - Answer D
A _________ is a digital representation of information that identifies you as a relevant
entity by a trusted third party?
A Digital Signature
B Hash
C Ownership stamp
D Digest - Answer A
What is the standard used by most digital certificates?
A X.509
B CRL
C RFC 2298
D OCSP - Answer A
DES uses keys of what size?
,A 56 bits
B 192 bits
C 128 bits
D 64 bits - Answer A
Which of the following is NOT a key size used by AES?
A 512 bits
B 128 bits
C 192 bits
D 256 bits - Answer A
Which of the following was a multi alphabet cipher widely used from the 16th century
(1553) to the early 20th century (1900s)?
A Vigenere
B Caesar
C Atbash
D Scytale - Answer A
Which of the following is a substitution cipher used by ancient Hebrew scholars?
A Caesar
B Vigenere
C Scytale
D Atbash - Answer D
Shifting each letter in the alphabet a fixed number of spaces to the right or left is an
example of what?
A Bit shifting
B Confusion
C Multi substitution
D Single substitution - Answer D
Which of the following most accurately defines encryption?
A changing a message so it can only be easily read by the intended recipient
B Making binary changes to a message to conceal it
C changing a message using complex mathematics
D Applying keys to plain text - Answer A
If you use substitution alone, what weakness is present in the resulting cipher text?
, A It is the same length as the original text
B It is easily broken with modern computers.
C It is too simple.
D Because it maintains letter and word frequency. - Answer D
_____ uses at least two different shifts, changing the shift with different letters in the
plain text.
A Atbash
B multi-alphabet encryption
C Scytale
D Caesar cipher - Answer B
____ was designed to provide built in cryptography for the clipper chip.
A Blowfish
B Skipjack
C GOST
D 3DES - Answer B
Which of the following uses an 80 bit key on 64 bit blocks?
A Twofish
B AES
C Skipjack
D DES - Answer C
With _____, the message is divided into blocks and each block is encrypted separately.
This is the most basic mode for symmetric encryption.
A Electronic codebook (ECB)
B Cipher-block chaining (CBC)
C Cipher feedback (CFB)
D Output feedback (OFB) - Answer A
Which of the following is an example of an unbalanced Feistel?
A 3DES
B Skipjack
C Twofish
D AES - Answer B
This process is done by having each block of plaintext is XORed with the previous
ciphertext block before being encrypted.
CRYPTOGRAPHY 2024 PROCTORED EXAM
QUESTIONS WITH DETAILED VERIFIED
SOLUTIONS AND RATIONALE /A+ GRADE
ASSURED
What type of encryption uses different keys to encrypt and decrypt the message?
A Symmetric
B Private key
C Secure
D Asymmetric - Answer D
The most widely used asymmetric encryption algorithm is what?
A RSA
B Vigenere
C DES
D Caesar Cipher - Answer A
Original, unencrypted information is referred to as ____.
A text
B plaintext
C cleantext
D ciphertext - Answer B
Which of the following is NOT an asymmetric system?
A PGP
B RSA
C SSL
D DES - Answer D
In order for User A to send User B an encrypted message that only User B can read,
User A must encrypt message with which of the following keys?
A User A's public key
B User A's private key
C User B's public key
D User B's private key - Answer C
,The greatest weakness with symmetric algorithms is _____.
A They are less secure than asymmetric
B The problem of key exchange
C They are slower than asymmetric
D The problem of generating keys - Answer B
Which of the following is generally true about block sizes?
A Smaller block sizes increase security
B Block sizes must be more than 256 bits to be secure
C Block size is irrelevant to security
D Larger block sizes increase security - Answer D
A _____ is a function that takes a variable-size input m and returns a fixed-size string.
A Symmetric cipher
B Hash
C Asymmetric cipher
D Feistel - Answer B
Which of the following is a cryptographic protocol that allows two parties to establish a
shared key over an insecure channel?
A Elliptic Curve
B RSA
C MD5
D Diffie-Hellman - Answer D
A _________ is a digital representation of information that identifies you as a relevant
entity by a trusted third party?
A Digital Signature
B Hash
C Ownership stamp
D Digest - Answer A
What is the standard used by most digital certificates?
A X.509
B CRL
C RFC 2298
D OCSP - Answer A
DES uses keys of what size?
,A 56 bits
B 192 bits
C 128 bits
D 64 bits - Answer A
Which of the following is NOT a key size used by AES?
A 512 bits
B 128 bits
C 192 bits
D 256 bits - Answer A
Which of the following was a multi alphabet cipher widely used from the 16th century
(1553) to the early 20th century (1900s)?
A Vigenere
B Caesar
C Atbash
D Scytale - Answer A
Which of the following is a substitution cipher used by ancient Hebrew scholars?
A Caesar
B Vigenere
C Scytale
D Atbash - Answer D
Shifting each letter in the alphabet a fixed number of spaces to the right or left is an
example of what?
A Bit shifting
B Confusion
C Multi substitution
D Single substitution - Answer D
Which of the following most accurately defines encryption?
A changing a message so it can only be easily read by the intended recipient
B Making binary changes to a message to conceal it
C changing a message using complex mathematics
D Applying keys to plain text - Answer A
If you use substitution alone, what weakness is present in the resulting cipher text?
, A It is the same length as the original text
B It is easily broken with modern computers.
C It is too simple.
D Because it maintains letter and word frequency. - Answer D
_____ uses at least two different shifts, changing the shift with different letters in the
plain text.
A Atbash
B multi-alphabet encryption
C Scytale
D Caesar cipher - Answer B
____ was designed to provide built in cryptography for the clipper chip.
A Blowfish
B Skipjack
C GOST
D 3DES - Answer B
Which of the following uses an 80 bit key on 64 bit blocks?
A Twofish
B AES
C Skipjack
D DES - Answer C
With _____, the message is divided into blocks and each block is encrypted separately.
This is the most basic mode for symmetric encryption.
A Electronic codebook (ECB)
B Cipher-block chaining (CBC)
C Cipher feedback (CFB)
D Output feedback (OFB) - Answer A
Which of the following is an example of an unbalanced Feistel?
A 3DES
B Skipjack
C Twofish
D AES - Answer B
This process is done by having each block of plaintext is XORed with the previous
ciphertext block before being encrypted.
