CERI2018G - Break a cryptosystem
We denote $\varphi$ the Euler's totient function.
The goal of the problem is to crack a message using a simplified RSA cryptosystem.
Here $(n, e)$ denotes the public key, and $c$ a crypted message.
The first line of the input consist of a single integer number t which determines the number of tests.
In each of next t lines there is three integer numbers n, e and c.
- 0 < t ≤ 10 000
- 0 < n ≤ 100 000 000, is the product of two distinct prime numbers (p, q)
- 0 < e ≤ 100 000 000, is coprime with $\varphi(n)$
- 0 ≤ c < n
Print $m$ such that
- the result of $m^e$ modulo $n$ is equal to $c$ ;
- $0\leq m < n$.
Input: 1 55 7 18 Output: 2
I think it's good classical problem.
Is it not an easy problem?
brake(english) means freiner (french)