This is a very difficult internet puzzle that was started on 4chan by a anonymous group named 3301. The goal of the Cicada project is to recruit highly intelligent individuals to solve ciphers and other secret messages. There is not much known about Cicada 3301. They did place physical clues in the locations seen below for users to find.
All of the puzzle were focused on security, anonymity, cryptography, and they used PGP signature in all of there messages to let others confirm that it was a message from the real authors. Each part of the puzzle is very advanced and they cover a lot of topics from old play references to math and very new computer science. The first message was released onto 4chan that said:
“Hello. We are looking for highly intelligent individuals. To find them, we have devised a test. There is a message hidden in the image. Find it, and it will lead you on the road to finding us. We look forward to meeting the few who will make it all the way through. Good luck.”Cicada 3301
There really was a hidden message, and when you decoded it, it outputted a imgur link, but it was a decoy image and did not contain useful information for those who are trying to solve the mystery.
Below you can find the real decoded message. It mentioned that the 3301 group would sign all of their future messages with a PGP (Pretty Good Privacy) key, and they listed the long string of random numbers below the message.
Hash: SHA1 - From here on out, we will cryptographically sign all messages with this key. It is available on the mit keyservers. Key ID 7A35090F, as posted in a2e7j6ic78h0j. Patience is a virtue. Good luck. 3301
The next decoded message led to a phone number (2143909608) that you could call to receive this audio. This is an archived version of it because the phone number does not exist anymore.