# From Factorisation of semiprimes to breaching confidentiality

If someone or some group found an efficient way to factor large composites with two distinct prime divisors, would this make it easier to decode any messages?

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Please add some details to your question: What cryptosystem are you using? – Paŭlo Ebermann May 2 '14 at 20:22

## 1 Answer

I guess it depends on which scenario you are referring to. If it is RSA, being able to factorize $n = pq$ would compromise the security of that crypto-system.

This is because one could compute $\phi(n) = \phi(p)·\phi(q) = (p-1)·(q-1)$ since $p$, $q$ are two distinct primes and could calculate the private key $d$ from the public key $e$ by using the equation $e \cdot d = 1 \mod \phi(n)$.

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