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MCQ | Cryptography Ciphers (Level: Easy) | Set 2

Here, we have a set of multiple-choice questions and answers (quiz) on ciphers in Cryptography (basic concepts of Cryptography Techniques and different types of ciphers).
Submitted by Monika Sharma, on February 02, 2020

1) You are supposed to use hill cipher for encryption technique. You are provided with the following matrix,

    A   =   [   4  2
                2  1 ]

Is the given matrix 'A', a valid key to be used for encryption?

  1. Yes
  2. No
  3. Can't be determined
  4. Data insufficient

Answer: b) No

Explanation:

For choosing any square matrix as a key, it should be taken care that the matrix is invertible, i.e. its inverse must exist. Here, in this case,

    | A | = 0

Therefore, it means that 'A' is not an invertible matrix. Hence matrix 'A' cannot be chosen as a key matrix for encryption in the Hill cipher.


2) The DES (Data Encryption Standard) cipher follows the fiestal structure. Which of the following properties are not shown by the fiestal structure?

  1. The input text is divided into two parts: one being left half and another one being right half.
  2. Swapping of the left and right halves are performed after each round.
  3. The plain text is converted into a matrix form first
  4. None of the above

Answer: c) The plain text is converted into a matrix form first

Explanation:

The fiestal structure does not require the conversion of the plain text into matrix form at any of its steps.


3) Among the following given options, chose the strongest encryption technique?

  1. DES ( Data Encryption Standard)
  2. Double DES
  3. Triple DES
  4. AES (Advance Encryption Standard)

Answer: d) AES (Advance Encryption Standard)

Explanation:

It has been proved that the AES performs much better than the all the other DES, whether it be single DES or series of DES.


4) What is the full-form of RSA in the RSA encryption technique?

  1. Round Security Algorithm
  2. Rivest, Shamir, Adleman
  3. Robert, Shamir, Addie
  4. None of the above

Answer: b) Rivest, Shamir, Adleman

Explanation:

The RSA algorithm was named after the three scientists who developed this technique and the name RSA is itself the abbreviation of their names: Rivest, Shamir, and Adleman.


5) Consider the following steps,

  1. Substitution bytes
  2. Shift Rows
  3. Mix columns
  4. Add round key

The above steps are performed in each round of which of the following ciphers?

  1. Rail fence cipher
  2. Data Encryption Standard (DES)
  3. Advance Encryption Standard (AES)
  4. None of the above

Answer: c) Advance Encryption Standard (AES)

Explanation:

Each round of AES includes the mentioned steps.


6) Codes and ciphers are different ways to _____ a message.

  1. Encrypt
  2. Decrypt
  3. Both A and B
  4. All of the mentioned above

Answer: c) Both A and B

Explanation:

Codes and cyphers are two separate methods of encrypting and decrypting messages. Using a code, you may make any message more or less meaningful by substituting each word with another that has a different meaning.


7) _____ ciphers encrypt uniformly sized blocks of data.

  1. Set
  2. Block
  3. Rack
  4. All of the mentioned above

Answer: b) Block

Explanation:

Block cyphers are used to encrypt data in blocks of consistent size. A block cypher takes a block of plaintext bits and generates a block of ciphertext bits, which are typically the same size as the plaintext blocks they are given. In the given system, the size of the block is fixed at a certain size.


8) Images can also be encrypted in sentences,

  1. True
  2. False

Answer: A) True

Explanation:

Images can also be encoded in the form of phrases. Steganography is the term used to describe this. Steganography is a type of encryption procedure in which you write one thing but truly mean something completely different when you read it.


9) Decryption is a process to unveil the ______.

  1. Unsecured data
  2. Secured data
  3. Insecure
  4. None of the mentioned above

Answer: b) Secured data

Explanation:

Decryption is a process to unveil the secured data, and for it, the structure obtains and transforms the mixed-up data and modifies it into an accessible language and image for both the reader along the system.


10) Symmetric encryption gathers plain-text data and then shuffles it to make it unreadable.

  1. True
  2. False

Answer: a) True

Explanation:

Simple text data is collected and then shuffled in order to render it unreadable using symmetric encryption. And, just before it reaches the intended.


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