ZK Hack Lisbon

From March 31st through April 2nd, the city of Lisbon played host to ZK Hack’s very first in-person Zero-Knowledge hackathon, ZK Hack Lisbon. Hosted at the stunning academy of science, It was a spectacle that saw the coming together of a diverse collection of brilliant minds, all geared towards exploring the potential of ZK tools & applications.

The event served as an incredible platform for hackers and builders to connect, collaborate, and learn from the leading teams in the ZK space. With a jam-packed schedule that included everything from workshops to team formations and of course some good old hacking; ZK Hack Lisbon was an unequivocal celebration of ZK technology and its potential to transform our digital world.

The evening of March 31st kicked off the event with an opening ceremony that set the stage for the exciting days ahead. The participants formed teams and dived right into an intro to zk circuit programming workshop, setting the tone for the intense hacking sessions that were to follow.

April 1st was a day full of enlightening workshops. The day started off with a tutorial on ‘Creating Zero-Knowledge Proofs with RISC Zero’, which shed light on the fascinating world of RISC Zero and its role in zk proofs. Next, ‘zkConnect: The Cryptonative SSO?’ by Sismo took centre stage, exploring the potential of zk technology in creating a Single Sign-On (SSO) for the crypto space.

The afternoon session was kicked off by a workshop on ‘Hacking on Polygon’s Zero Knowledge Virtual Machines’, offering insights into the intricacies of Polygon’s zkVMs. The day continued with a session on ‘Privacy on Polkadot via XCM’ by Moonbeam, followed by ‘Pragmatic Privacy with Liminal’ by Aleph Zero, each adding a different facet to the understanding of privacy in the blockchain space. 

Finally, April 2nd was the culmination of all the hard work and innovation, with the submission of the hacks and the judging process. While every submission was a testament to the incredible talent and potential in the zk space, the winning solutions stood out for their innovation, practicality, and potential impact on real-world applications of ZK technology. 

ZK Hack Lisbon: Closing Ceremony, Bounties and Prizes

1st Place: ZeroGravity

@drCathieSo_eth, @SecuritaAegis, @georgwiese, @benwilson_ml, @VicSintNic, @unzvfu – 

ZeroGravity, a weightless neural network architecture to reduce the proving of inference to lookup arguments on a highly optimised Bloom filter implementation.

ZeroGravity addresses the inherent complexities of expressing popular neural network architectures as arithmetic circuits for zero-knowledge proofs. Capitalising on previous advancements in Weightless Neural Networks (WNNs) and lookup arguments, ZeroGravity streamlines the proof of neural network training and inference. The project uniquely employs an optimised Bloom filter for inference via table lookups, replacing traditional floating-point arithmetic. In practical terms, this technology enables users to confidentially verify that their biometric data, processed through an ML model, is not blacklisted, thereby bolstering the integrity of data provenance in ML-based medical scans.

2nd Place: ZKP2P

 @0xSachinK, @Bmwball56, @richardzliang,

A trustless P2P USD <-> USDC fiat onramp powered by ZK proofs and Venmo

ZKP2P is aimed at simplifying the process of onboarding and offboarding funds in the web3 space. It addresses key challenges faced by new users, such as high fees charged by centralised exchanges, and limitations experienced by crypto natives who want to offboard funds into the real world. ZKP2P leverages Zero-Knowledge Proofs (ZKPs) of email DKIM signatures to facilitate on-chain trading of USDC for USD with a Venmo user, offering a decentralised solution that enhances accessibility and reduces costs. This innovative use case is built on the ZK Email platform.

3rd Place: zkSafe 


Enabling to use your @Safe with your web2 accounts thanks to Sismo zkConnect.

zkSafe improves account control by integrating web2 accounts like email or Twitter with your wallet. Leveraging the Gnosis Safe Module framework and Sismo zkConnect single sign-on, it provides enhanced security and convenience. Features include social recovery through your trusted network and advanced access control based on Sismo claims and levels. With zkSafe, you can manage these off-chain rules confidently, backed by the privacy-preserving assurances of zk proofs, making self-custody more resilient and flexible!

Hackers’ choice: Fruity Friends


Fruity Friends intends to solve the case when two people share common interests, such as fruits they like, but are unwilling to reveal any of them unless it matches the other person’s interests.

Fruity Friends addresses the challenge of Private Set Intersections (PSI) – discovering shared interests between individuals without revealing any non-matching preferences. Essentially, it aims to identify commonalities while maintaining privacy. The primary focus is on determining if there are any shared interests (i.e., the intersection’s cardinality is greater than 0).

Honorable Mentions

1: Zero Trace: a zkSocial graph to authorise computation and storage at the edge.

2: StarkSight: Verify your World ID (ZK-SNARK), on Starknet.

3: Zero Knowledge Decision Tree Prediction (ZK-DTP)

4: ZyKloon: a solution that allows anonymous transactions between accounts that belong to the same sismo vault.

5: Sismord: a simple integration of SISMO’s zkConnect protocol which provides an off-chain verification using ZKPs that checks if you can gain access to private discord memberships.

As the event wrapped up on Sunday, it was clear that ZK Hack Lisbon was more than just a hackathon. It was a vibrant community event, a celebration of knowledge, and a testament to the potential of zk technology.

We want to extend our congratulations to all the winners and participants, who not only showed incredible talent but also contributed to the overall success of ZK Hack Lisbon. We are excited about the future of ZK and can’t wait to see how the seeds planted at this event will grow and shape the landscape of ZK technology.

Thank you to everyone who made ZK Hack Lisbon possible – our dedicated team, the inspiring participants, and our supportive community. You have truly made this event a landmark in the journey of ZK technology. We learned a lot about hosting hackathons on our first outing, and we look forward to seeing you at our next event which is slated for later this year in Istanbul! For the latest updates and more, follow us on twitter Twitter, also make sure to pop into the discord to join the conversation.

Table of Contents