How to prove your cryptoidentity anonymously

Published in
5 min readJun 13, 2019


Today there is quite a number of progressive projects that would benefit greatly from formalizing people on the Internet. It could allow for democratic voting and fair value distribution, free speech platforms without abuse, and privacy-preserving authentication. Neither government nor biometrics, neither social login nor SSI are able to cover all the essential criteria: uniqueness, humanity, anonymity, decentralization, and independence of the third party (read more here).

Idena is offering a comprehensive and consistent unique cryptoidentity framework without custody. It is fully decentralized and based on a time-synchronized ritual of solving AI-resistant puzzles called flips.

We define cryptoidentity as a manifestation of a conscious human that can be proven online and recorded on the blockchain. In contrast with digital identity, cryptoidentity does not need personal data or verifiers to confirm you as a real person. It requires instead a two-part proof: of humanness and uniqueness.

Let us see how Idena works and meets the suggested identity criteria.

No personal data sharing to preserve anonymity

Idena does not require any personal data sharing and does not reveal a person’s identity.

To use Idena for sending messages and funds, you will just need to download the app. To create a digital person, you should receive an invitation code from a validated participant of the network and use the code to apply for validation.

Time synchronization to verify the participant’s uniqueness

A validation that takes place at a synchronized time will allow verifying uniqueness of the network participants.

Idena certifies a participant’s account for the consequent epoch (a time period before the next validation session) during regular validation sessions. At a certain known time, flips are assigned to all participants of the network and solved by them within the allotted time period. All the answers are transacted to the network.

To prevent buying multiple accounts, a fraction of the reward is frozen as a stake in the network, and the coins can be taken only when “killing” your own identity in Idena. When buying an account, the buyer receives a copy of the private key. The initial owner can any time afterward invalidate the account and get the frozen coins. So, the buyer is at risk that the purchased accounty can be “killed” any time in the future.

Turing tests to prove humanness

A Turing test is widely used online to tell humans from bots in the form of the CAPTCHA. Ironically, it is quite useless to prove humanness as it relies on a kind of perception for which AI can be trained.

Idena proposes a language-neutral AI-hard test (an analogue of the Winograd Schema Challenge without the textual representation) that conveys narrative rather than semantic meaning. A flip, “Filter for Live Intelligent People”, utilizes four images that act like the scenes in a movie. To solve a flip, you choose between two sequences of these images, only one of which makes narrative sense. The other one is deliberately distorted so that the picture sequence would not make up a story (read more here).

To make a flip truly AI-hard and to avoid the need for a trusted third party, flips must be human-generated. In Idena flips are created by validated participants, encrypted and stored in the P2P network.

To create a flip, you:

  1. Use two random keywords suggested by the app as associative hints to think up a story within the general template “Before — Something happens — After”.

2. Upload four images to tell the story you have in mind.

3. Create an alternative — a meaningless sequence of the images you have chosen for your story. Shuffle the pictures of your story in such a way that it would not be a meaningful story any longer.

4. Save the flip and then submit it to the network.

The network awards coins for each valid flip.

Collective decentralized self-validation to avoid the need for a trusted third party

The results of the test are collectively self-validated. This is done statistically as the accuracy rate of the test’s completion is known, so there is no need for a trusted third party.

The network reaches consensus on the flip answers, scores the accuracy, and approves validated accounts. It also punishes participants for creating invalid flips (with no consensus on the correct answer) or flips with inappropriate content. All the validated participants receive a reward in coins that can be used for the network services (sending messages and funds, and in the future — many more).

The participant’s identification persists for as long as the current epoch lasts. During the epoch, the validated participant gains special privileges, including the ability to invite new users, mine new blocks and get rewards, propose protocol improvements, and create new flips.

After the validation expires by the end of the epoch, participants revalidate themselves with a new synchronized test.

The suggested Idena network architecture allows for anonymous proof of humanity and proof of uniqueness for the network participants. No personal data sharing, no revealing of a person’s identity, no third-party identification center — just a decentralized network of people mutually validating their humanness and uniqueness.

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Proof-of-Person blockchain. Idena is a novel way to formalize people on the web: