got it, special thanks to @Kucharskov . feel free to PM me. @Xh4H great challenge thank you
Thank you @Xh4H for this challenge! It required a bit of basic socket programming before I was on my way to figuring out the flag. This is one of the rare few in the crypto category that has any relation and relevance to modern cryptography.
I was working on a creating a very similar challenge so when I saw it I immediately thought what it could be xD… quite surreal
fun challenge tho!
I feel satisfied solving this challenge and I learned something new too…happy to help anyone who needs help
Can’t figure out what cryptosystem is in play here. I have a general idea of how to attack, but don’t know how to parse what I’m seeing in order to apply the attack.
It’s like going back to childhood … xD
Thanks for this challenge @Xh4H
Got it. This was very satisfying. To get traction you need to have some familiarity with what the typical crypto is for communication sessions. It’s basically an inference, especially since the language is used a bit loosely. (This was the hardest part for me! I went back and did research and did a few relevant exercises. Then I got hung up on parsing, which was not necessary.) Then you need to try to see if there are patterns or commonalities in what you see from instance to instance. Finally there is some simple math. Knowing how things are typically done is helpful. (fwiw I didn’t do any socket programming – nothing nearly that complicated)
LMK if you want some hints.
@Xh4H ■■■!!! Really really nice challenge! I love these kind of math. I will respect you. That motivates me to get a higher graduation in informatics.
I used python to solve this challenge. The mathematics behind this topics is really interesting and understandable, but the programming-part was hard (for me…). I didn’t find online tools/online calculators.
edit got it it was really an intresting challenge its all about some basic mathematics knowledge that i was missing every time thanks for any one that helps me i was blind as usual hahah
going for mission impossible now
Struggling to identify the cryptosystem… any hints?
Coming back to read all your coments, im really happy you enjoyed the challenge, stay tuned, more is coming 
can any one tell youtube channel or course to study cryptography
How did other menu options help me to get the flag?