Network Security · Computer Networks · GATE CSE

The value of 3⁵¹ mod 5 is_________.

A sender S sends a message m to receiver R, which is digitally signed by S with its private key. In this scenario, one or more of the following security violations can take place.

I. S can launch a birthday attack to replace m with a fraudulent message.
II. A third party attacker can launch a birthday attack to replace m with a fraudulent message.
III. R can launch a birthday attack to replace m with a fraudulent message.

Which of the following are possible security violations?

Anarkali digitally signs a message and sends it to Salim. Verification of the signature by Salim requires

Suppose that everyone in a group of N people wants to communicate secretly with the N - 1 others using symmetric key cryptographic system. The communication between any two persons should not be decodable by the others in the group. The number of keys required in the system as a whole to satisfy the confidentiality requirement is

Which one of the following are used to generate a message digest by the network security protocols?
(P) RSA
(Q) SHA-1
(R) DES
(S) MD5

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?

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

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?

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

Exponentiation is a heavily used operation in public key cryptography. Which of the following options is the tightest upper bound on the number of multiplications required to compute (bⁿ mod m),$$0 \le b,n \le m$$?

A sender is employing public key Cryptography to send a secret message to a receiver. Which one of the following statement is true?

In an RSA cryptosystem, the value of the public modulus parameter n is 3007. If it is also known that $$\varphi $$(n) = 2880, where $$\varphi $$() denotes Euler's Totient Function, then the prime factor of n which is greater than 50 is ______.

Consider that B wants to send a message m that is digitally signed to A. Let the pair of private and public keys for A and B be denoted by $$K_x^ - $$ and $$K_x^ + $$ for x = A, B, respectively. Let K_x(m) represent the operation of encrypting m with a key K_x and H(m) represent the message digest. Which one of the following indicates the CORRECT way of sending the message m along with the digital signature to A?

In the RSA public key cryptosystem, the private and public keys are (e, n) and (d, n) respectively, where n = p$$ \times $$q and p and q are large primes. Besides, n is public and p and q are private. Let M be an integer such that 0 < M < n and f(n) = (p - 1)(q - 1). Now consider the following equations.

I. M'= M^e mod n
M = (M')^d mod n

II. ed ≡ 1 mod n

III. ed ≡ 1 mod $$\phi $$(n)

IV. M'= M^e mod $$\phi $$(n)
M = (M')^d mod $$\phi $$(n)

Which of the above equations correctly represent RSA cryptosystem?

The total number of keys required for a set of n individuals to be able to communicate with each other using secret key and public key crypto-systems, respectively are:

Suppose that two parties A and B wish to setup a common secret key (D - H key) between themselves using the Diffie-Hellman key exchange technique. They agree on 7 as the modulus and 3 as the primitive root. Party A chooses 2 and party B chooses 5 as their respective secrets. Their D - H key is