# How does RSA decryption works? [closed]

I have this exercise:

we have the following RSA public key $n = 275398901700898900724918474136345950999$
$e = 5$
Alice encrypts the message $M$ with the native RSA. She computes $C = M^e \pmod n$ and sends to Bob $C = 170841202002112185870598344402287193795$ Recover the original message $M$.

I'm playing some ctf online. I'm new in crypto and just want to know if I can decrypt the message using a tool.

• – Biv
Aug 3, 2016 at 9:38
• and mode
– Biv
Aug 3, 2016 at 9:39
• did you actually search ?
– Biv
Aug 3, 2016 at 9:39
• I'm voting to close this question as off-topic because it is a dump of a homework question. Aug 3, 2016 at 9:42

1. Factorise $n$
2. find $d$ the private key using $\varphi(n)$ and the extended euclidean algorithm.
3. compute $C^d \pmod n$ this should be your initial $M$.