hacker.org

The message is a plain text, not a cipher.
I guess that's a mistake.

Yes, I think it's a mistake.
The message Charly intercepted should be 10121894195639241422027618825432423752630721992693703529919

I probably wasted an hour looking for my calculation error in decrypting the message. o_O
Ok, back to hacking my Mortal Coil solver. (:

That has to be a mistake, this challenge has difficulty 75 only to convert a given number to readable ASCII?

(Before doing the conversion I suspected the answer could be a sentence like that based on the challenge description )

With MSieve (http://sourceforge.net/projects/msieve/) prime number factorization took only 11 minutes on my intel core duo Amazing tools out there!

http://factordb.com/ gives an even faster answer

Hmm, seems it was originally much more simple I had to factorize the 80 digit number.
It's helpfull when one knows there are downloadable number field sieve algorithms available . Took me about 2 hours after reaching the challenge .

... this challenge sucked. I'm pretty disappointed by it.

I was hoping to learn something and not just to use (online) tools to factor a number. This is not a good challenge.