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Considering RSA, $n=p\,q$ with $p,q$ odd primes and the public key $(n,e)$, where $\gcd(e,\phi(n))=1$, I need a hint on how to show that the number of plaintexts with $E_e(x)=x$ equals $\gcd(e-1,p-1)\cdot gcd(e-1,q-1)$. So we are searching for the number of plaintexts that remain unchanged by the encryption function using the public key.

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  • $\begingroup$ Sights! HW problem! $\endgroup$
    – kelalaka
    Commented May 6, 2021 at 15:00
  • $\begingroup$ Your ego is wrong. It's from a textbook I'm self-studying. Asked for a hint and not a solution, yet here you are bragging about your "homework discovery". Such behavior is toxic to the community and your karma. Have a nice day stranger. $\endgroup$
    – John333
    Commented May 6, 2021 at 16:07
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    $\begingroup$ it is not ego, it is an inference that the same question occurred twice in the last two days. Happy to hear that you are asking for your self-learning. Here we have a policy about HW problems that we don't answer and only provide hints. Have fun at learning. $\endgroup$
    – kelalaka
    Commented May 6, 2021 at 16:10

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