The author went out of their way to hide the factors of N, presumably so that nobody else would actually be able to generate signed certificates. However, they did this by hiding half the digits of the factors.
Revealing so many digits of the factors actually allows easily factoring the original number using a version of coppersmith's method (easy as in under a second on my laptop instead of the 9 hours on a distributed cluster the authors used). This is actually a pretty classic CTF exercise.
If I'm still nerdsniped by this tomorrow I'll try my hand at implementing this and factoring the number myself
Revealing so many digits of the factors actually allows easily factoring the original number using a version of coppersmith's method (easy as in under a second on my laptop instead of the 9 hours on a distributed cluster the authors used). This is actually a pretty classic CTF exercise.
If I'm still nerdsniped by this tomorrow I'll try my hand at implementing this and factoring the number myself