CRY302 Exam Questions and Answers 2023/2024
1. __________ techniques map plaintext elements (characters, bits) into ciphertext
elements.
A) Transposition
B) Substitution
C) Traditional
D) Symmetric - ANSW B) Substitution
2. Joseph Mauborgne proposed an improvement to the Vernam cipher that uses a
random key that is as long as the message so that the key does not need to be
repeated. The key is used to encrypt and decrypt a single message and then is
discarded. Each new message requires a new key of the same
length as the new message. This scheme is known as a(n) __________ .
A) pascaline
B) one-time pad
C) polycipher
D) enigma - ANSW B) one-time pad
3. An original intelligible message fed into the algorithm as input is known as
_________ , while the coded message produced as output is called the __________ .
A) decryption, encryption
B) plaintext, ciphertext
C) deciphering, enciphering
D) cipher, plaintext - ANSW B) plaintext, ciphertext
4. Restoring the plaintext from the ciphertext is __________ .
A) deciphering
B) transposition
C) steganography
D) encryption - ANSW A) deciphering
5. A __________ attack involves trying every possible key until an intelligible translation
of the ciphertext is obtained.
A) brute-force
B) Caesar attack
C) ciphertext only
D) chosen plaintext - ANSW A) brute-force
,6. Techniques used for deciphering a message without any knowledge of the
enciphering details is ___________ .
A) blind deciphering
B) steganography
C) cryptanalysis
D) transposition - ANSW B) steganography
7. The ___________ takes the ciphertext and the secret key and produces the original
plaintext. It is essentially the encryption algorithm run in reverse.
A) Voronoi algorithm
B) decryption algorithm
C) cryptanalysis
D) diagram algorithm - ANSW B) decryption algorithm
8. If both sender and receiver use the same key, the system is referred to as:
A) public-key encryption
B) two-key
C) asymmetric
D) conventional encryption - ANSW D) conventional encryption
9. __________ attacks exploit the characteristics of the algorithm to attempt to deduce
a specific plaintext or to deduce the key being used.
A) Brute-force
B) Cryptanalytic
C) Block cipher
D) Transposition - ANSW B) Cryptanalytic
10. The __________ was used as the standard field system by the British Army in
World War I and was used by the U.S. Army and other Allied forces during World War II.
A) Caesar cipher
B) Playfair cipher
C) Hill cipher
D) Rail Fence cipher - ANSW B) Playfair cipher
11. The __________ attack is the easiest to defend against because the opponent has
the least amount of information to work with.
A) ciphertext-only
B) chosen ciphertext
C) known plaintext
D) chosen plaintext - ANSW A) ciphertext-only
, 12. _________ refer to common two-letter combinations in the English language.
A) Streaming
B) Transposition
C) Digrams
D) Polyalphabetic cipher - ANSW C) Digrams
13. A way to improve on the simple monoalphabetic technique is to use different
monoalphabetic substitutions as one proceeds through the plaintext
message. The general name for this approach is ___________ .
A) rail fence cipher
B) cryptanalysis
C) polyalphabetic substitution cipher
D) polyanalysis cipher - ANSW C) polyalphabetic substitution cipher
14. A technique referred to as a __________ is a mapping achieved by performing
some sort of permutation on the plaintext letters.
A) transposition cipher
B) polyalphabetic cipher
C) Caesar cipher
D) monoalphabetic cipher - ANSW A) transposition cipher
15. The methods of __________ conceal the existence of the message in a graphic
image.
A) steganography
B) decryptology
C) cryptology
D) cryptography - ANSW A) steganography
T F 1. Symmetric encryption remains by far the most widely used of the
two types of encryption. - ANSW T
T F 2. Rotor machines are sophisticated precomputer hardware devices
that use substitution techniques. - ANSW T
T F 3. Symmetric encryption is a form of cryptosystem in which
encryption and decryption are performed using different keys. It is
also known as non- conventional encryption. - ANSW F
T F 4. With the use of symmetric encryption, the principal security
problem is maintaining the secrecy of the key. - ANSW T
1. __________ techniques map plaintext elements (characters, bits) into ciphertext
elements.
A) Transposition
B) Substitution
C) Traditional
D) Symmetric - ANSW B) Substitution
2. Joseph Mauborgne proposed an improvement to the Vernam cipher that uses a
random key that is as long as the message so that the key does not need to be
repeated. The key is used to encrypt and decrypt a single message and then is
discarded. Each new message requires a new key of the same
length as the new message. This scheme is known as a(n) __________ .
A) pascaline
B) one-time pad
C) polycipher
D) enigma - ANSW B) one-time pad
3. An original intelligible message fed into the algorithm as input is known as
_________ , while the coded message produced as output is called the __________ .
A) decryption, encryption
B) plaintext, ciphertext
C) deciphering, enciphering
D) cipher, plaintext - ANSW B) plaintext, ciphertext
4. Restoring the plaintext from the ciphertext is __________ .
A) deciphering
B) transposition
C) steganography
D) encryption - ANSW A) deciphering
5. A __________ attack involves trying every possible key until an intelligible translation
of the ciphertext is obtained.
A) brute-force
B) Caesar attack
C) ciphertext only
D) chosen plaintext - ANSW A) brute-force
,6. Techniques used for deciphering a message without any knowledge of the
enciphering details is ___________ .
A) blind deciphering
B) steganography
C) cryptanalysis
D) transposition - ANSW B) steganography
7. The ___________ takes the ciphertext and the secret key and produces the original
plaintext. It is essentially the encryption algorithm run in reverse.
A) Voronoi algorithm
B) decryption algorithm
C) cryptanalysis
D) diagram algorithm - ANSW B) decryption algorithm
8. If both sender and receiver use the same key, the system is referred to as:
A) public-key encryption
B) two-key
C) asymmetric
D) conventional encryption - ANSW D) conventional encryption
9. __________ attacks exploit the characteristics of the algorithm to attempt to deduce
a specific plaintext or to deduce the key being used.
A) Brute-force
B) Cryptanalytic
C) Block cipher
D) Transposition - ANSW B) Cryptanalytic
10. The __________ was used as the standard field system by the British Army in
World War I and was used by the U.S. Army and other Allied forces during World War II.
A) Caesar cipher
B) Playfair cipher
C) Hill cipher
D) Rail Fence cipher - ANSW B) Playfair cipher
11. The __________ attack is the easiest to defend against because the opponent has
the least amount of information to work with.
A) ciphertext-only
B) chosen ciphertext
C) known plaintext
D) chosen plaintext - ANSW A) ciphertext-only
, 12. _________ refer to common two-letter combinations in the English language.
A) Streaming
B) Transposition
C) Digrams
D) Polyalphabetic cipher - ANSW C) Digrams
13. A way to improve on the simple monoalphabetic technique is to use different
monoalphabetic substitutions as one proceeds through the plaintext
message. The general name for this approach is ___________ .
A) rail fence cipher
B) cryptanalysis
C) polyalphabetic substitution cipher
D) polyanalysis cipher - ANSW C) polyalphabetic substitution cipher
14. A technique referred to as a __________ is a mapping achieved by performing
some sort of permutation on the plaintext letters.
A) transposition cipher
B) polyalphabetic cipher
C) Caesar cipher
D) monoalphabetic cipher - ANSW A) transposition cipher
15. The methods of __________ conceal the existence of the message in a graphic
image.
A) steganography
B) decryptology
C) cryptology
D) cryptography - ANSW A) steganography
T F 1. Symmetric encryption remains by far the most widely used of the
two types of encryption. - ANSW T
T F 2. Rotor machines are sophisticated precomputer hardware devices
that use substitution techniques. - ANSW T
T F 3. Symmetric encryption is a form of cryptosystem in which
encryption and decryption are performed using different keys. It is
also known as non- conventional encryption. - ANSW F
T F 4. With the use of symmetric encryption, the principal security
problem is maintaining the secrecy of the key. - ANSW T
