# Computer Fundamentals Questions and Answers – Cryptography

This set of Computer Fundamentals Multiple Choice Questions & Answers (MCQs) focuses on “Cryptography”.

1. These ciphers replace a character or characters with a different character or characters, based on some key.
a) Polyalphabetic substitution based
b) Transposition-based
c) Substitution based
d) Mono alphabetic substitution based

Explanation: In mono alphabetic substitution-based cipher, a character is replaced with some other character or multiple characters, based on some key.

2. Encryption is the study of creating and using decryption techniques.
a) True
b) False

Explanation: The statement is false. Cryptography is the study of creating and using encryption and decryption techniques.

3. A type of cipher that uses multiple alphabetic strings.
a) Substitution based
b) Transposition-based
c) Polyalphabetic substitution based
d) Mono alphabetic substitution based

Explanation: These ciphers are similar to that of mono alphabetic ciphers. Multiple strings are used to encode the plain text.

4. An encryption technique with 2 keys is ______________
a) Monoalphabetic Cipher
b) Cryptography
c) Private key cryptography
d) Public key cryptography

Explanation: It is called as public key cryptography. It has 2 keys: a private key and a public key.

5. In public key cryptography, a key that decrypts the message.
a) public key
b) unique key
c) private key
d) security key

Explanation: Public key cryptography has 2 keys. They are private key and a public key. The public key encrypts the message. The private key decrypts the message.
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6. DES stands for?
a) Data Encryption Standard
b) Data Encryption Statistics
c) Data Encryption System
d) Data Encryption Sequence

Explanation: DES stands for Data Encryption Standard. It was created in 1977 and went into operation from 1990s.

7. Under DES, the data encryption standard took a 64-bit block of data and subjected it to ______ levels of encryption.
a) 64
b) 8
c) 16
d) 4

Explanation: The answer is 16. It was subjected to 16 levels of encryption. DES is the data encryption standard.

8. Triple-DES has ______ keys.
a) 1
b) 2
c) 5
d) 4

Explanation: There are 2 keys in triple DES as well. The private and the public key. It can also have 3 unique keys.

9. Encryption standard that is selected by the US government to replace DES.
a) AES
b) BES
c) CES
d) DES

Explanation: AES is Advanced Encryption Standard. It was selected by the US government. It is used to replace DES.

10. An electronic document that establishes your credentials when you are performing transactions.
a) Digital code
b) OTP
c) E-mail
d) Digital certificate

Explanation: Digital certificate is an electronic document that is responsible for secure internet transactions.

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