Question 1

__________ encryption is a form of cryptosystem in which encryption and decryption are performed using the same key.

Accepted Answer

The answer of __________ encryption is a form of cryptosystem...

Question 2

An encryption scheme is said to be __________ if the cost of breaking the cipher exceeds the value of the encrypted information and the time required to break the cipher exceeds the useful lifetime of the information.

Accepted Answer

The answer of An encryption scheme is said to be...

Question 3

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

Accepted Answer

The decryption algorithm is the inverse of the encryption algorithm and takes the ciphertext and the secret key to produce the original plaintext.

Question 4

Cryptographic systems are characterized along three independent dimensions: the type of operations used for transforming plaintext to ciphertext; the way in which the plaintext is processed; and __________ .

Accepted Answer

The answer of Cryptographic systems are characterized along three independent...

Question 5

One of the simplest and best known polyalphabetic ciphers is _________ cipher.In this scheme, the set of related monoalphabetic substitution rules consists of the 26 Caesar ciphers with shifts of 0 through 25.Each cipher is denoted by a key letter which is the ciphertext letter that substitutes for the plaintext letter 
A.

Accepted Answer

The answer of One of the simplest and best known...

Question 6

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

Accepted Answer

When both the sender and receiver use the same key for encryption and decryption, the system is referred to as conventional encryption, also known as symmetric encryption.

Question 7

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

Accepted Answer

The Playfair cipher was used as the standard field system by the British Army in World War I and was also used by the U.S. Army and other Allied forces during World War II. It was considered a strong encryption method at the time due to its simplicity and ease of use in the field.

Question 8

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

Accepted Answer

The polyalphabetic substitution cipher uses multiple substitution alphabets to encrypt the plaintext, making it more secure than a simple monoalphabetic cipher.

Question 9

A __________ cipher processes the input one block of elements at a time, producing an output block for each input block, whereas a stream cipher processes the input
elements continuously, producing output one element at a time.

Accepted Answer

The answer of A __________ cipher processes the input one...

Question 10

techniques used for deciphering a message without any knowledge of the enciphering details is ___________ .
A) blind deciphering
B) steganography
C) cryptanalysis
D) transposition

Accepted Answer

Cryptanalysis is the study of analyzing information systems to understand the hidden aspects of the systems, often used to decipher messages without prior knowledge of the encryption details.

Question 11

All encryption algorithms are based on two general principles: substitution and
____________ .

Accepted Answer

The answer of All encryption algorithms are based on two...

Question 12

__________ 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

Accepted Answer

Cryptanalytic attacks specifically target the weaknesses in the underlying algorithm of a cryptographic system, aiming to deduce plaintext or the cryptographic key without the need for brute force.

Question 13

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

Accepted Answer

The ciphertext-only attack is the easiest to defend against because in this scenario, the attacker only has access to the ciphertext without any knowledge of the corresponding plaintext or the encryption key, making it the most challenging for them to decipher the message.

Question 14

the earliest known, and simplest use, of a substitution cipher was called the __________ cipher and involved replacing each letter of the alphabet with the letter standing three places further down the alphabet.

Accepted Answer

The answer of the earliest known, and simplest use, of...

Question 15

_________ refer to common two-letter combinations in the English language.
A) Streamings
B) Transpositions
C) Digrams
D) Polyalphabetic ciphers

Accepted Answer

Digrams are pairs of letters that frequently appear together in a language, such as "th" in English.

Question 16

An encryption scheme is __________ secure if the ciphertext generated by the scheme does not contain enough information to determine uniquely the corresponding plaintext, no matter how much ciphertext is available.

Accepted Answer

The answer of An encryption scheme is __________ secure if...

Question 17

A technique for hiding a secret message within a larger document or picture in such a way that others cannot discern the presence or contents of the hidden message is __________ .

Accepted Answer

The answer of A technique for hiding a secret message...

Question 18

the two types of attack on an encryption algorithm are cryptanalysis, based on properties of the encryption algorithm, and _________ which involves trying all possible keys.

Accepted Answer

The answer of the two types of attack on an...

Question 19

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

Accepted Answer

A transposition cipher is a method of encryption by which the positions held by units of plaintext (which are commonly characters or groups of characters) are shifted according to a regular system, so that the ciphertext constitutes a permutation of the plaintext. This is different from substitution ciphers, where units of plaintext are replaced with ciphertext according to a fixed system.

Question 20

the methods of __________ conceal the existence of the message in a graphic image.
A) steganography
B) decryptology
C) cryptology
D) cryptography

Accepted Answer

Steganography is the practice of concealing a file, message, image, or video within another file, message, image, or video. The key idea is to hide the existence of the message, which differentiates it from cryptography that protects the content of the message but does not hide the existence of the message.

Quiz 3: Classical Encryption Techniques

__________ encryption is a form of cryptosystem in which encryption and decryption are performed using the same key.

An encryption scheme is said to be __________ if the cost of breaking the cipher exceeds the value of the encrypted information and the time required to break the cipher exceeds the useful lifetime of the information.

the ___________ takes the ciphertext and the secret key and produces the original plaintext.It is essentially the encryption algorithm run in reverse.

Cryptographic systems are characterized along three independent dimensions: the type of operations used for transforming plaintext to ciphertext; the way in which the plaintext is processed; and __________ .

If both sender and receiver use the same key, the system is referred to as:

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 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 __________ cipher processes the input one block of elements at a time, producing an output block for each input block, whereas a stream cipher processes the input elements continuously, producing output one element at a time.

techniques used for deciphering a message without any knowledge of the enciphering details is ___________ .

All encryption algorithms are based on two general principles: substitution and ____________ .

__________ attacks exploit the characteristics of the algorithm to attempt to deduce a specific plaintext or to deduce the key being used.

the __________ attack is the easiest to defend against because the opponent has the least amount of information to work with.

the earliest known, and simplest use, of a substitution cipher was called the __________ cipher and involved replacing each letter of the alphabet with the letter standing three places further down the alphabet.

_________ refer to common two-letter combinations in the English language.

An encryption scheme is __________ secure if the ciphertext generated by the scheme does not contain enough information to determine uniquely the corresponding plaintext, no matter how much ciphertext is available.

A technique for hiding a secret message within a larger document or picture in such a way that others cannot discern the presence or contents of the hidden message is __________ .

the two types of attack on an encryption algorithm are cryptanalysis, based on properties of the encryption algorithm, and _________ which involves trying all possible keys.

A technique referred to as a __________ is a mapping achieved by performing some sort of permutation on the plaintext letters.

the methods of __________ conceal the existence of the message in a graphic image.