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الأحد، 1 مايو 2022

Information Security 1

 


1-      Data Encryption Standard (DES) is considered as an example of Symmetric ciphers

 

2-      The number 14 is co-prime to 26 "خطأ"

 

3-      The one-time pad is considered to be unconditionally secure "صح"

 

4-      when the data is used by limited number of private user, and should not be known to the majority of workers, we call it as Confidential

 

5-      Primarily responsible for assessment, management, and implementation of IS in the organization  Chief Information Security Officer (CISO)

 

6-      The Caesar Cipher is sometimes referred to as the Shift cipher

 

7-      .............................. gaining access to system or network using known or previously unknown/newly discovered access mechanism Back doors

 

8-      If we use Cesar cipher to encrypt “ENGINEER” using key = 8. Then, we obtain ---------------------- as a ciphertext. Note that Z=25, 0=26. MVOQVMMZ, None of these

9-      If we use extended Vigenere cipher (26 English letters and 10 decimal digits) to encrypt “COM09” using key word “Covid19”. Then, we obtain ---------------------- as a ciphertext. Note that Z=25, 0=26, 1=27, 2=28…... Hint: Use modular arithmetic  .   None of these

10-   In asymmetric key cryptography, the key is known by sender and receiver"خطأ"

11-  Apply the brute force attack on the captured cipher "Yeyzks” to obtain the used key.  Note: Caesar cipher is used for encryption of English alphabetic. Just write the value of the key in your answer 6

12-  What is “Symmetric encryption”:
A form of cryptosystem in which encryption and decryption are performed using the same key

13-  RC4 is an example of Stream ciphers

14-  A modification attack is an attack against the -------------------------service data integrity

 

 

15-  …………………attacker monitors network packets, modifies them, and inserts them back into network Man-in-the-middle

 

16-  Cryptography means secret writing "صح"

 

17-  In symmetric key cryptography, the key is known by  sender and receiver

 

18-  The estimated computations required to crack a password of 5 characters from the 28 letter alphabet is 17,210,368

 

Dose 17 has a multiplicative inverse in mod 26 "صح

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