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WorksheetsNetwork Defence
Total questions: 20
Worksheet time: 5mins
what is encryption in the context of network security?
Authenticating users based on their unique characteristics
Hiding the true source of network traffic
Scanning network traffic of malicious patterns
Converting plaintext data into cipertext to prevent unauthorized access
Which of the following is NOT a security service defined in OSI security architecture?
Confidentiality
Integrity
Availability
Compression
In a Caesar cipher, if the key is 3, what is the cipher text of "CYBER"?
KHOOR
FBEHU
GDKKN
JGNNQ
In the symmetric cipher model, which key is used for decryption?
Same key as encryption
No key is used
Public key
A different key from encryption
Which of these is NOT a substitution cipher?
Playfair Cipher
Vigenère Cipher
Rail Fence Cipher
Hill Cipher
Simplified DES (SDES) operates on a block size of:
12 bits
8 bits
14 bits
4 bits
what is the purpose of access control mechanisms in network security?
To prevent unauthorized users from accessing sensitive resources
To increase network speed and reduce latency
To monitor network traffic for performance optimization
To create backups of user data automatically
An algorithm in encryption is called______________?
Algorithm
ciper
procedure
module
what is the common name for the caesar ciper, a basic encryption technique?
Transposition cipher
Asymmetric cipher
Shift cipher
symmetric cipher
An example of poly alphabetic substitution is_________________?
P-box
S-box
Caesar cipher
Vigenere cipher
Which of the following is an example of a passive attack?
Denial of Service (DoS)
Traffic Analysis
SQL Injection
Man-in-the-Middle
A replay attack occurs when:
A hacker modifies data during transmission.
A hacker captures and retransmits valid data packets.
A hacker floods a server with requests.
A hacker guesses passwords by brute force
The encryption formula for Caesar cipher is:
C=(P−K)mod26
C=(P×K)mod26
C=P⊕K
C=(P+K)mod 26
The decryption formula for the Vigenère cipher is:
P=(C−K)mod26
C=(P+K)mod26
P=(K−C)mod26
P=(C+K)mod26
The first step in SDES key generation is:
P8 permutation
Left shift (LS-1)
P10 permutation
Initial permutation (IP)
RSA is named after the researchers (_____ ) who proposed it
River, Shamir, Adleman
Rivest, Shamus, Adleman
Rivest, Shamir, Adleman
Rivest, Shamir, Adlemar
In RSA, Ф(n) = _______ in terms of p and q.
(p-1)(q-1)
(p)(q)
(p)/(q)
(p+1)(q+1)
RSA formula of encryption and decryption
Encryption
C = M mod n
Decrytion
M = C mod n
Decrytion
C = Me mod n
Encryption
M = Cd mod n
Encryption
M = Me mod n
Decrytion
C = Cd mod n
Encryption
C = Me mod n
Decrytion
M = Cd mod n
If Alice's private key is aaa and Bob's public key is BBB, what is the formula for the shared secret key?
gaB mod p
Ba mod p
aB mod p
B+a mod p
What is Alice’s public key & Bob’s public key ?
Bob’s public key
A=ga mod p
Alice’s public key
B=gb mod p
Bob’s public key
A=g mod p
Alice’s public key
B=g mod p
Alice’s public key
B=ga mod p
Bob’s public key
A=gb mod p
Alice’s public key
A=ga mod p
Bob’s public key
B=gb mod p
