Question 1

Using public key cryptography, X adds a digital signature [Tex]\\sigma[/Tex] to message M, encrypts < M, [Tex]\\sigma[/Tex] >, and sends it to Y, where it is decrypted. Which one of the following sequences of keys is used for the operations?

Question 2

In the RSA public key cryptosystem, the private and public keys are (e, n) and (d, n) respectively, where n = p*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’= MWhich of the above equations correctly represent RSA cryptosystem?^{e}mod n M = (M’)^{d}mod n II. ed ≡ 1 mod n III. ed ≡ 1 mod f(n) IV. M’= M^{e}mod f(n) M = (M’)^{d}mod f(n)

Question 3

Which of the following are used to generate a message digest by the network security protocols?

(P) RSA (Q) SHA-1 (R) DES (S) MD5

Question 4

A sender is employing public key cryptography to send a secret message to a receiver. Which one of the following statements is TRUE?

Question 5

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 represent the operation of encrypting m with a key Kx 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?

Question 6

Consider the following two statements:
i. A hash function (these are often used for computing digital signatures) is an injective function.
A. 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?

Question 7

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 b^{n} mod m,0≤b,n≤m ?

Question 8

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:

Question 9

How many of the above statements are true?S1- MD5 is vulnerable to the Birthday attack.S2- traceroute uses the "Destination port unreachable" ICMP error message.S3- 3DES is a type of Public Key Encryption Algorithm.S4- IPv6 has a 40-byte fixed header size(without Options fields).

Question 10

In a RSA cryptosystem, a participant A uses two prime numbers p=13 and q=11 to generate his public and private keys. If the public key of A is 37, then the private key of A is _____.

There are 40 questions to complete.

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