October 12, 2023
October 12, 2023
October 12, 2023
###### Database-Management-System
October 12, 2023
 Question 16
Using ‘RSA’ public key cryptosystem, if p=3, q=11 and d=7, find the value of e and encrypt the number ’19’
 A 20,19 B 33,11 C 3,28 D 77,28
Question 16 Explanation:
n= P*q
n= 3*11
n=33
ф(n) = (p-1)(q-1)
ф(n) = 2*10
ф(n) = 20
E * d=1 mod ф(n)

e*7=1 mod 20
Now find the value of “e” in such a way that if we multiply the value of “e” with 7 then by dividing it with 20 mod value should come as “1”.
So if e=3 then the above condition can be satisfied hence option C is the right answer.
Encrypted value = (Message)e mod n
= (19)3 mod 33
= 28
Question 16 Explanation:
n= P*q
n= 3*11
n=33
ф(n) = (p-1)(q-1)
ф(n) = 2*10
ф(n) = 20
E * d=1 mod ф(n)

e*7=1 mod 20
Now find the value of “e” in such a way that if we multiply the value of “e” with 7 then by dividing it with 20 mod value should come as “1”.
So if e=3 then the above condition can be satisfied hence option C is the right answer.
Encrypted value = (Message)e mod n
= (19)3 mod 33
= 28