There is another IDENA thread and is way more active:

https://bitcointalk.org/index.php?topic=5194871.msg55749679#msg55749679

You are solving touring test to prove network that you are human - not bot. That in front of your node stands real person. That's the end of creating your IDENA identity. All idena needs to know about is is that you are not bot. Then you are able to mine/vote.

According to privacy comparing IDENA to coins like monero. Idena is not anonymous, you can track transactions like on etherum or bitcoin.