Signing Factory Discussion [CRYPTO]

HackTheBox
1

Let’s talk about Signing Factory. Please do not share any flags or writeups.

2

Solving equations are easy. Here’s a one liner to solve it

from sympy import mod_inverse
from functools import reduce

#copy the equations from the server
eq = ['equation(unknown, 2287183127, 2654435761) = 1919930493', 'equation(unknown, 2586616559, 2654435761) = 1307538604', 'equation(unknown, 2419030907, 2654435761) = 1691244225']

h_n = reduce(lambda acc, i: (acc * (int(i.split()[-1]) * mod_inverse(int(i.split()[1][:-1]), 2654435761)) % 2654435761), eq, 1)
print(h_n)
3

Then factor the admin hash, you know what to do…