coingate challenges

Do not be paranoid, there is no hint hidden here.


We hope Challenge #15 put you on your toes! Read below for our thoughts on the last round as well as solutions for the last three riddles. Next round of CoinGate Challenges is on Saturday, September 30, 6 PM UTC – and we are planning to add some swag to it!

We will immediately urge you to subscribe to our mailing list on our challenges page. Yes, we are that cheap. But it helps us believe people like this stuff.

Our team are really enjoying the growing interest in our challenges. In spite of the fact the riddles are quite technical and require knowledge (or at least interest in) specific topics, the number of people taking part is steadily rising. We are not that great with social media, but we love to engage the community, especially the geeky Reddit kind.

During the weekend, we had over 3,000 pageclicks on our Challenge pages! That is pretty big for us, and more than twice what we had on any of the previous rounds. Kudos to everyone who took part and grinded the until the end. That being said, we will likely stick to having one tough riddle – we just like to see you guys sweat! 

The last round of CoinGate Challenges lasted the whole weekend, actually! We thought our contestants would get annoyed, but apparently, more people visited our challenge pages on Sunday than on Saturday, and only early Monday was challenge #15 actually solved (not without a hint, though). Congrats to u/flyingapples123! Many tried, but only one prevailed – which is kind of a shame since there is only one prize…

So, for the next round, we will be adding some Bitcoin swag from one of our new merchants –! We will most likely pick some random winners or the sorest losers, but let’s keep it under wraps for now. In the meantime, consider supporting the store and pick up something! After all, this seems to be one of the few stores that make something customized and non-ugly.


The solutions are on challenge sub-pages already. For your convenience, we are including them below.

#13: The solution was to multiply the large number by 7, write a “0” in front of it, and then convert the resulting decimal number to ASCII.

#14: The solution was to replace all vowels with “0”, and all consonants with “1”. This gave a binary code which, when converted to ASCII and added to “”, gave the link to where the private key was.

#15: To solve the challenge, several steps were needed:

  1. Decode the string with ROT47.
  2. Decode the answer from the first step with ROT5 (only numbers get rotated).
  3. XOR the answer from the second step together with hash (SHA256) of the word “CoinGate”. This word was hidden in the source code of the page and marked as “password”.
  4. Take the first letter of the result from the third step, skip the next 33 symbols, take the symbol after that, skip the next 33 symbols, etc. If arriving at end of the string, continue from the beginning of the string, until the private key is formed.

You can find CoinGate Challenges and subscribe to our mailing list here: – stay stuned and stay sharp! 

Yours truly,


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