GATE CSE 2013 | Network Security Question 8 | Computer Networks

GATE CSE 2013

MCQ (Single Correct Answer)

-0.3

Using public key cryptography, X adds a digital signature σ to message M, encrypts, and sends it to Y, where it is decrypted. Which one of the following sequences of keys is used for the operations?

Encryption: X's private key followed by Y's private key;
Decryption: X’s public key followed by Y’s public key

Encryption: X's private key followed by Y's public key;
Decryption: X's public key followed by Y's private key

Encryption: X's public key followed by Y's private key;
Decryption: Y's public key followed by X's private key

Encryption: X's private key followed by Y's public key;
Decryption: Y's private key followed by X's public key

GATE CSE 2011

MCQ (Single Correct Answer)

-0.3

A layer-4 firewall (a device that can look at all protocol headers up to the transport layer) CANNOT

block entire HTTP traffic during 9:00 PM and 5:00 AM

block all ICMP traffic

stop incoming traffic from a specific IP address but allow outgoing traffic to the same IP address

block TCP traffic from a specific user on a multi-user system during 9:00 PM and 5:00 AM

GATE CSE 2007

MCQ (Single Correct Answer)

-0.3

Consider the following two statements:

i. A hash function (these are often used for computing digital signatures) is an injective function.
ii. encryption technique such as DES performs a permutation on the elements of its input alphabet.

Which one of the following options is valid for the above two statements?

Both are false

Statement (i) is true and the other is false

Statement (ii) is true and the other is false

Both are true

GATE CSE 2007

MCQ (Single Correct Answer)

-0.3

The minimum positive integer p such that (3^p modulo 17) = 1 is