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2 votes
2 votes

Plz tell me how to solve this .I am feeling problem o calculate --

10 = p^5 mod 35 . How to solve this type of question quickly.

2 Answers

Best answer
4 votes
4 votes
Given n = 35, that means p and q must be 5 and 7

Now we need to calculate $\phi$(n) = (p - 1) (q - 1)
Therefore $\phi$(n) = 24

Now we need to select e and d in such a way that (e x d) mod $\phi$(n) = 1
Given e = 5
i.e ( 5 x d ) mod 24 = 1

Going by options only option a satisties i.e d = 5  { 25 mod 24 = 1 }, So private key will be (5, 35).
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Option A is correct.here public key(e =5,n=35) so we first choose two distinct prime number p and q such that n = p *q. So we find p=7 and q=5, now we will have to find phi(n)=p-1 * q-1 = 6*4=24.

So public key is given (e=5,n=35),now we will find 5*d mod 24 =1.on checking options d=5 satisfy the remainder 1....

So (5,35) is the answer.

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