Progress Update: Stealth Address Standardization and Umbra Enhancements

February 20, 2024 / Ben DiFrancesco

It's been just over two months since we announced ScopeLift had received funding from the EF to advance stealth address standardization and improve Umbra. Much has been accomplished in that time. We're excited to share our progress with you.

Adding our part to the Ethereum ecosystem

Stealth Address ERCs

The team has been hard at work moving ERC-5564 and ERC-6538 forward. Both have since been updated and refined based on feedback from the community and reviewers. The contracts for both ERCs are now at "Release Candidate" stage. This means they have been rigorously tested and are effectively complete. Both contracts are currently under audit by Trail of Bits. We anticipate publishing the audit results upon completion around the end of the month.

Moreover, we're developing a "first party" stealth address TypeScript SDK, aiming to simplify the integration process for developers building on top of the ERCs. While not a canonical part of the standard itself, we believe offering the SDK will be critical for adoption. An Alpha version of this SDK is already available for experimentation and contribution on GitHub at ScopeLift/stealth-address-sdk.

Umbra v1 Improvements

While we're focused on advancing stealth addresses via the new standards, we are not neglecting Umbra v1, which remains the most widely used stealth address protocol in all of crypto. In the last two months, Umbra has seen significant enhancements aimed at improving user experience and expanding functionality:

  • USDC Support: Umbra v1 now supports native USDC transactions on all Layer 2 networks where it is available. Bridged USDC, called "USDC.e", also remains available.
  • Performance and Usability: We've dedicated effort to squash bugs and enhance performance. Additionally, users have new control over the scanning process, with the ability to pause or stop it as needed.
  • Decentralized Hosting: Embracing decentralization to its core, the Umbra v1 frontend is now hosted on IPFS and accessible via ENS at

Looking Ahead

In the next two months, we're setting our sights on several goals:

  • Finalizing the smart contract bytecode and ERCs for both stealth address contracts.
  • Deploying canonical instances on testnets to facilitate broader testing and integration.
  • Releasing a beta version of the TypeScript SDK on npm to enhance developer accessibility.
  • Further improving Umbra v1, including its deployment on an additional Layer 2 network.
  • Beginning to share our initial plans and architecture for Umbra v2 with the community.

Overall, we remain on track with the milestones we published at the beginning of the year:

Time frameMilestone
✅ CompleteRelease candidate ERC contracts ready for public review and scrutiny
✅ CompleteAlpha release of the TypeScript SDK
🟡 In ProgressERC contracts audited by Trail of Bits
Early MarchERC contracts deployed to testnet(s)
Mid MarchInitial Umbra v2 plans published
Late MarchBeta TypeScript SDK released
Late AprilFinal contracts deployed on major EVM networks
Mid MayProduction-ready version of the TypeScript SDK is published
Late MayPreliminary Umbra v2 architecture docs, diagrams, prototypes, and mockups are published


We want to once again reiterate our thanks to all those who continue to support our work to push the boundaries of stealth address adoption on the EVM. This includes, of course, the Ethereum Foundation, whose grant is currently funding our work, along with the Gitcoin community, which has long sustained Umbra's development. It also includes the badgeholders of Optimism's RetroPGF Round 3, who voted to provide another critical source of funding. While we know the rewards are "retrospective", we fully intend to put them to use advancing stealth addresses.

Finally, we want to thank the developer community which has shown such interest in what we're working on. Hundreds of people have joined the public working group Telegram channel, and we invite you to as well. Ultimately, our goal is to make stealth addresses a ubiquitous and seamlessly integrated technology in wallets and apps in the EVM ecosystem. This can only happen with developer adoption, so we're gratified to see interest so high.

There's lots left to do. Stay tuned!