Event Recap: World’s 1st World Cup zk-Guessing

zCloak Network
5 min readDec 28, 2022

zCloak Network launched the world’s first “World Cup zk-Guessing” event on December 1st. The 4-phase event lasted through the whole month of December, and as its completion was just announced by zCloak, here’s a recap of everything that happened.

As you may already know, we have updated the beta version of our zkID Credential Platform and the zkID Wallet to zCloak’s own W3C compatible DID and Verifiable Credential protocol in November, and soon started our WCG zk-Guessing Event as our first event to introduce the updated version of the platform and the wallet to the public. For more details on products&tech, please refer to the tech version of the event recap.

Here’s what happened during each phase of the event:

Phase I — Guess and Record

At this phase, users made guesses of the champion team, record it as a verifiable credential (VC), and shared their credential with the zCloak verifier to make a commitment. A total of 3723 DIDs were registered. We received 1704 successful shares by selective disclosure. Users who only shared their discord user name and the discord verification code, leaving out their guessed team, were deemed as successful shares.

Phase II — Zero-Knowledge Proof for Semi-Finals

At this phase, all successful users from phase I proved to us whether their guessed team reached the Semi-Finals with a zero-knowledge program ran on their local devices. Since no one shared their guessed team with us in the first place, we were able to verify the successful users without knowing which team they guessed, but only that their team entered the Semi-Finals. We have received 204 ZKPs from our users who guessed correctly in phase II. We performed a raffle for half of our prize pool ($1,000) and 20 lucky winners were published on our event page.

Phase III — Who is the champion?

At this phase, the champion has already won the world cup, and the users who guessed Argentina in the first place can finally reveal the credential to us for being able to participate in the second lucky draw. We have received 86 credentials who guessed Argentina to be the World Cup Champion. We performed a raffle for the other half of our prize pool ($1,000) and 5 lucky winners were published on our event page, and they are also rewarded with Player Pass NFT Whitelists provided by our partner Macondo.

Phase IV — Claim your prizes

At this phase, all successful participants from phase I are eligible to claim POAP/OAT prizes from our partners including BuidlerDAO, Flock&Tusima, Mirror World, MoleDAO, SnapFingersDAO, and Web3Go. We collected all participants ETH addresses on our event website. 638 users submitted their addresses successfully and were able to claim the attractive rewards powered by all our partners.

This event is the first time that zero-knowledge proof technology is used in the guessing of world-class sports events. With the help of zCloak’s privacy-preserving decentralized identity protocol, users were able to make a cryptographic commitment on the championship team, in the form of Verifiable Credential, on their local devices. This system enables users to make a guess of the champion team without disclosing which team it is.

When the World Cup reaches the semi-finals, users performed zero-knowledge proof computation locally in their zkID browser wallet to generate a zk-proof. They were able to prove their guessed team has entered the the World Cup semi-finals without disclosing the name of the team. The winning users participated in the lucky draw and shared half of the prize pool. Later, after the World Cup 2022 final match is over, users who have successfully predicted the champion team presented the full text of their verifiable credential to zCloak verifier and participated in the drawing of the remaining prize pool.

The guessing and raffle process described above demonstrates how a user-friendly privacy-preserving use case is achieved in daily scenarios. Extending this to the real gambling and prediction industry, relevant cryptography technologies can be used to effectively conceal the prediction trend in advance, thereby preventing the game results from being manipulated by humans. Such use cases are unimaginable in the Web2 world, and can only be achieved by combining Web3’s user sovereign data and cryptography technologies such as zero-knowledge proofs.

We are happy to see our community’s enthusiasm and active participation, and will continue bringing more meaningful events to our members in the future! Please also read our tech version of the event recap if you’re interested, where we provide a more detailed explanation of our product and the design of this event.

Also, we would like to direct you to our new Christmas Card Event to further enjoy what our products can bring in this holiday season! We wish you a very merry Christmas and hopefully the Web3 dream of Self-Sovereignty will be delivered by the zCloak team soon!

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zCloak Network

zCloak Network is a Real-World Identity (RWI) infrastructure for Web3. Website: zcloak.network; Product: zkid.app