Network Security

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?

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’= Me mod n
    M = (M’)d mod n 

II.  ed ≡ 1 mod n 

III. ed ≡ 1 mod f(n)

IV. M’= Me mod f(n)
    M = (M’)d mod f(n) 

Which of the above equations correctly represent RSA cryptosystem?

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

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

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?

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?

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≤b,n≤m ?

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:

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).

How many of the above statements are true?

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 _____.