What is more interesting than 50 shades of gray?
It’s verifying emails in a privacy friendly way on-chain on Kusama, of course.
Zero Knowledge & Cryptography Bounty:
This work is funded by the independent Kusama’s ZK & Advanced Cryptography Bounty, read more about the program here: https://zk.kusama.vision/
The Kusama Bounty has funded the first proposal by the ZK-email Team.
Background:
ZK email is an impressive ZK team that started a project during a hackathon. A dream to be able to verify emails privately on-chain. Two years later, the project has exploded and built an ecosystem of developers and inspiring future projects.
Words from ZK-email team:
For the past two years, our team has been building cryptographic infrastructure that connects Web2 identity with Web3 actions. Using zero-knowledge proofs, ZK Email lets anyone verify email ownership on-chain without revealing the email’s content, the recipient, or any sensitive data.
Until now, our deployment and verification pipeline has been deeply tied to EVM-compatible environments. This proposal changes that. We are porting ZK Email directly to PolkaVM, allowing Polkadot-native applications to verify email proofs on-chain without bridging to EVM environments.
Public talks:
ZK Email: Fast Proofs and Production-Ready Account Recovery | Devcon SEA
ZK Email @ EthCC 2024: Decentralized Email Login + Account Recovery + 2FA
As we move towards Kusama being a home to future unstoppable privacy applications, The Cryptography Bounty is very happy to be collaborating with the ZK-email team to bring email verification to kusama but also to provide everyone with PolkaVM optimized tooling for future ZK developers.
Anything that has a confirmation email, you can now build cool smart contracts around
50 use cases a developer can build on Kusama with ZK Email
If it lands in your inbox, it can settle on-chain. Here are 50 shades of it.
By utilizing ZK-email we can have smart contracts that verify that the email has been received without revealing the email. This unlocks a wide range of usecases, for example have you ever bought a second hand music ticket? And it turns out that the event ticket you bought is fake? Now you can lock X amount of tokens into a smart contract and say i want to buy tickets for Adell or similar and if someone has bought a ticket from ticket master and gotten a ticket verification email. We can now verify that the seller has a legit ticket and can prove it, so that user can fulfill the order, two humans trading, transparently, authenticity of the product is privately verified on-chain. Embodying less trust, more truth. No more “trust me bro” photoshopped second hand tickets, now we can use math to privately prove that the ticket is legit, autonomously, on-chain.
Secondary markets & ticketing (resell by proving the purchase email)
- 1. Ticketmaster v2 ( trustless resale of any event ticket)
- 2. Second-hand concert tickets
- 3. Second-hand football tickets
- 4. Second-hand basketball tickets
- 5. Festival passes & wristband resale
Secondary market for verified authentic festival/events tickets, maybe anonymous web3 summit ticket market place?
- 6. Airline seat / booking resale
- 7. Hotel reservation resale
- 8. Restaurant reservation (Resy/OpenTable no-show) market
Marketplaces & commerce
9. Privacy-friendly Purse.io / Amazon (pay in KSM via order confirmation)
- Build a secondary marketplace that use amazon order confirmations to let people fulffil amazon orders on behalf of others and get paid in crypto, confirmation of sent order can be done privately and by a smart contract
10. Decentralized domain marketplace (Namecheap/GoDaddy transfer emails)
- Prove you own a Gandi|Namecheap|godaddy transfer email, and build marketplace atop it
11. Gift-card resale (prove balance email)
12. Warranty transfer market (purchase email → transferable warranty)
13. Proof-of-delivery escrow (shipping confirmation releases payment)
14. Proof-of-refund escrow (refund email unlocks funds)
15. Subscription/SaaS seat resale
Payment confirmations
16. Venmo/PayPal/CashApp receipt → fiat on-ramp to Kusama
17. Wise/Revolut transfer proof for P2P swaps
18. Bank-transfer confirmation → stablecoin mint
19. Recurring on-chain payments proven by subscription receipts
20. Dispute/chargeback email → payment insurance payoutv
Identity & reputation (prove a status without doxxing yourself)
21. Proof of employment (offer/payroll email)
22. Proof of income (payslip) → undercollateralized lending
23. Proof of student status (.edu enrollment) → discounts & airdrops
24. Proof of residence (utility bill) for local/regional DAOs
25. Proof of KYC-passed (exchange verification email), privately
26. Proof of age for gated content
27. Proof of credit score
28. Proof of airline/loyalty tier status
DAOs & governance
29. Sybil-resistant airdrops via unique institutional emails
30. Gated DAO membership (@company.com proof)
31. University/alumni DAOs (prove alumni email)
32. Conference attendance → POAP-style claims
33. Anonymous whistleblowing with provenance
- Press-credential-gated journalist collectives
Wallets & accounts
35. Email-based social recovery (guardians, no seed phrase)
36. Email as a multisig signer (approve by replying)
37. Send tokens to any email address (email wallet)
38. Email OAuth login with session keys + scopes
39. Email 2FA for high-value transactions
40. Dead-man’s-switch inheritance
41. Email-triggered generic contract calls (relayer + proof)
Proof of Experience
42. Proof of GitHub sponsorship → contributor rewards
43. “Donate to any academic paper” (prove authorship email)
44. Proof of flight / boarding pass → travel-insurance payout
45. Proof of pad Thai
46. Proof of food-delivery order → loyalty rewards. Proof of Burrito, prove that you have ordered a burrito without giving sensitive data away.
47. Proof of a dating-app match
48. Proof of “unsubscribe” / breakup email → a “moving on” NFT
49. Proof of newsletter subscription → gated Telegram/Discord
50. “Your order has shipped” → real-world-asset collateral
50 usecases… But there is more!
ZK email blueprints
A blueprint is a reusable recipe for one kind of email proof: you upload an example email, choose which fields to extract (sender domain, subject, a username, an order number) and mark each one public or private, and we write the regexes, compile the Circom circuit, and generate its matching verifier contracts for you. It turns “I received this email” into something a smart contract can check, with no circuit code or cryptography knowledge required. You can browse what others have already published, or create your own, at https://registry-staging.onrender.com
Read more and create or use a blueprint here:
The road so far:
Milestone 1 Complete: ZK Email Arrives on PolkaVM and the Paseo Testnet
We are delighted to share a promising update regarding one of our ecosystem grant initiatives. The team working on bringing ZK Email natively to PolkaVM and Kusama has officially wrapped up Milestone 1, and the delivered results are highly impressive.
The primary objective of this initial phase was to port the on-chain DKIM Registry from the standard EVM environment over to PolkaVM bytecode using the `resolc` compiler, followed by a successful deployment of a fully functional testnet version on the Paseo Asset Hub. This transition is a critical step in enabling verifiable, cryptographically secure email-based interactions directly within the Kusama ecosystem.
Here is a breakdown of everything delivered in milestone 1:
-
PolkaVM DKIM Registry: The core DKIM Registry contracts have been successfully recompiled and adapted, ensuring full compatibility and seamless operation within PolkaVM execution environments.
-
Paseo Testnet Deployment: The registry is now live and operational on the Paseo Asset Hub, allowing early adopters and infrastructure providers to interact with it directly.
-
Comprehensive Test Suite: To guarantee long-term stability, local test flows were configured using Foundry, rigorously validating key registration, rotation, and revocation behaviors under the new architecture.
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Interactive Demo dApp: To make testing accessible for developers and community members, we have a live, hands-on demo available for exploring key management flows.
We encourage everyone to explore the deliverables and test out the implementation:
- Interactive Demo: [dkim-demo.zk.email](http://dkim-demo.zk.email)
- Demo Readme & Setup: [ZK Email Verify - DKIM Registry Demo](https://github.com/zkemail/zk-email-verify/tree/kusama-grant/demo)
- Repository Branch**: [zkemail/zk-email-verify (kusama-grant branch)](GitHub - zkemail/zk-email-verify at kusama-grant · GitHub)
Note: Kusama is currently being added in zk-emails official documentation, as soon as this pr will be merged: docs: add Polkadot & Kusama section by benceharomi · Pull Request #36 · zkemail/docusaurus · GitHub
This milestone lays a solid technical foundation for trustless email verification on Kusama. We look forward to seeing the community engage with the demo and provide feedback as the project progresses toward its next milestones. Great work to the grantee team on reaching this critical milestone!
We want to push the boundaries of Zero Knowledge and PolkaVM, together with the ZK-email team and we are excited to have them on-board.
Sincerely,
Kusama Cryptography Bounty Curators + ZK-email Team
Edited by: flipchan