Skip to content
Related Articles

Related Articles

UGC-NET | UGC NET CS 2017 Jan – III | Question 29
  • Last Updated : 05 Apr, 2018
GeeksforGeeks - Summer Carnival Banner

In RSA public key cryptosystem suppose n = p ∗ q where p and q are primes. (e, n) and (d, n) are public and private keys respectively. Let M be an integer such that o < M < n and φ(n) = (p – 1)(q – 1). Which of the following equations represent RSA public key cryptosystem ?

     I. C ≡ Me(mod n)         
        M ≡ (C)d(mod n) 
    II.ed ≡ 1(mod n)
   III.ed ≡ 1(mod φ(n))           
    IV. C ≡ Me(mod φ(n))
        M ≡ Cd(mod φ(n))

Codes :
(A) I and II
(B) I and III
(C) II and III
(D) I and IV

Answer: (B)

Explanation: I is true because

Encrypted-Text = (Plain-Text)e mod n
    Plain-Text = (Encrypted-Text)d mod n 

III is true because

   d-1 = e mod ϕ(n)
Or ed = 1 mod ϕ(n)

II and IV is wrong.
So, option (B) is correct.

Quiz of this Question

Attention reader! Don’t stop learning now. Get hold of all the important DSA concepts with the DSA Self Paced Course at a student-friendly price and become industry ready.

My Personal Notes arrow_drop_up
Recommended Articles
Page :