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MCQ | Cryptography Basics

Here, we have a set of multiple-choice questions and answers (quiz) on cryptography basics (basic concepts of cryptography techniques).
Submitted by Monika Sharma, on February 02, 2020

1) Which of the following is not a type of symmetric-key cryptography technique?

  1. Caesar cipher
  2. Data Encryption Standard (DES)
  3. Diffie Hellman cipher
  4. Playfair cipher

Answer: c) Diffie Hellman cipher

Explanation:

The Diffie Hellman uses a pair of asymmetric keys for encryption and decryption processes. All the rest mentioned cipher techniques use the same key for encryption as well as decryption.


2) Which of the following is not a principle of data security?

  1. Data Confidentiality
  2. Data Integrity
  3. Authentication
  4. None of the above

Answer: d) None of the above

Explanation:

All the first three options are the principles of data security. None of the mentioned characteristics fall apart form these principles. Therefore, the correct answer is none of the above.


3) Which of the following security attacks is not an active attack?
OR
Which of the following attacks is a passive attack?

  1. Masquerade
  2. Modification of message
  3. Denial of service
  4. Traffic analysis

Answer: d) Traffic analysis

Explanation:

In a passive attack, the attacker does not modify any part of the data. His attempt is only to obtain the information and not to modify it. From the mentioned options, this happens only in Traffic analysis in which the attacker monitors the pattern of transmission. The rest other options are examples of active attacks.


4) Which of the following options correctly defines the Brute force attack?

  1. Brutally forcing the user to share the useful information like pins and passwords.
  2. Trying every possible key to decrypt the message.
  3. One entity pretends to be some other entity
  4. The message or information is modified before sending it to the receiver.

Answer: b) Trying every possible key to decrypt the message.

Explanation:

Only option b) is the correct definition for brute force attack.


5) "A key is a string of bits used by a cryptographic algorithm to transform plain text into ciphertext." Which of the following is capable of becoming a key in a cryptographic algorithm?

  1. An integer values
  2. A square matrix
  3. An array of characters (i.e. a string)
  4. All of the above

Answer: d) All of the above

Explanation:

As the key can be any string of bits, all the mentioned options are capable of becoming a key in a cryptographic algorithm.


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6) A mechanism used to encrypt and decrypt data.

  1. Cryptography
  2. Algorithm
  3. Data flow
  4. None of these

Answer: a) Cryptography

Explanation:

Cryptography is a mechanism used to encrypt and decrypt data.


7) To encrypt the plaintext, a cryptographic algorithm works in combination with a key...

  1. Word, number, or phrase
  2. Special Symbols
  3. Function Keys
  4. All of these

Answer: a) word, number and phrase

Explanation:

Word, number and phrase are used to encrypt the plaintext.


8) The plaintext encrypts to different cipher text with different keys

  1. True
  2. False

Answer: a) True

Explanation:

The plaintext is used to encrypt to different cipher text with different keys.


9) Conventional cryptography also known as ... encryption.

  1. asymmetric-key
  2. logical-key
  3. symmetric-key
  4. None of these

Answer: c) symmetric-key

Explanation:

Conventional cryptography also known as symmetric-key encryption.


10) The Data Encryption Standard (DES) is an example of a ...

  1. Conventional cryptosystem
  2. Asymmetric cryptosystem
  3. Caesar's cryptosystem
  4. All of these
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Answer: a) Conventional cryptosystem


11) Public key cryptography is a ... cryptosystem

  1. Symmetric
  2. Asymmetric
  3. Symmetric & Asymmetric both
  4. None of these

Answer: b) Asymmetric cryptosystem

Explanation:

Asymmetric is a public key cryptography.


12) Security Goals of Cryptography are

  1. Confidentiality
  2. Authenticityn
  3. Data integrityn
  4. Non-repudiation
  5. All of these

Answer: e) All of these

Explanation:

Confidentiality, authenticity, data integrity and non-repudiation security are the key goals of cryptography.


13) A process of studying cryptographic system is known as Cryptanalysis

  1. True
  2. False

Answer: a) True

Explanation:

Cryptanalysis is a process of studying cryptographic system.


14) Cipher in cryptography is –

  1. Encrypted message
  2. Algorithm for performing encryption and decryption
  3. Both algorithm for performing encryption and decryption and encrypted message
  4. Decrypted message

Answer: b) algorithm for performing encryption and decryption

Explanation:

Cipher in cryptography is an Algorithm for performing encryption and decryption.


15) The private key in asymmetric key cryptography is kept by

  1. Sender
  2. Receiver
  3. Sender and receiver
  4. All the connected devices to the network
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Answer: b) Receiver

Explanation:

The private key is kept by the receiver.


16) Which one of the following algorithms is not used in asymmetric-key cryptography?

  1. DSA algorithm
  2. Electronic code book algorithm
  3. Diffie-Hellman algorithm
  4. RSA algorithm

Answer: b) Electronic code book algorithm

Explanation:

The electronic code book algorithm is a block cypher method in which a block of data corresponds to each block of text in the encrypted message.


17) Which is the cryptographic protocol that is used to protect an HTTP connection?

  1. Resource reservation protocol
  2. SCTP
  3. TLS
  4. ECN

Answer: c) TLS (Transport Layer Security)

Explanation:

In order to prevent eavesdropping, tampering and message forgery, TLS has strong message authentication and key-material generation.


18) A key is a value that works with a cryptographic algorithm to produce a specific cipher text.

  1. True
  2. False

Answer: a) True

Explanation:

A key is a value that works with a cryptographic algorithm to produce a specific cipher text.


19) A Public key size and conventional cryptography’s secret key size are closely related with one another.

  1. True
  2. False

Answer: b) False

Explanation:

A Public key size and conventional cryptography’s secret key size are unrelated with one another.


20) ElGamal encryption system is an asymmetric key encryption algorithm.

  1. Public-key cryptography
  2. Private-key cryptography
  3. Both
  4. None of these

Answer: a) Public-key cryptography

Explanation:

The ElGamal encryption scheme in cryptography is an asymmetrical key encryption algorithm based on the Diffie-Hellman key exchange for public-key cryptography.


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