Solana World ID Program

This is an example of using Wormhole Queries to bridge the World ID state root from Ethereum to Solana.

Objective

Enable cross-chain World ID verification so that protocols can verify their users’ identities on Solana. This is accomplished in two parts:

Read, authenticate, and propagate the World ID state root from Ethereum to Solana.
Allow for protocols to authenticate users’ World IDs on-chain on Solana using those roots.

Background

World ID

Currently, the World ID state is managed on Ethereum in a privacy-preserving manner via an on-chain representation of the Semaphore set.

On Ethereum, on-chain verification of World IDs can be performed by calling verifyProof on the World ID Identity Manager contract (example) with a proof provided by the Tree Availability Service.

On-chain verification can be made available on other blockchains and is currently available on some Layer 2 EVMs, such as Polygon, Optimism, and Base, via their native bridges, the World ID State Bridge contracts, and the State Bridge Service. Integrators can use the bridged OpWorldID and PolygonWorldID contracts as they would the World ID Identity Manager contract on Ethereum.

Wormhole Queries

Wormhole Queries is a service that allows applications, developers, and users to access cross-chain data on-demand in an efficient and inexpensive manner. Queries leverages the Wormhole Guardians (some of the largest proof of stake validators in the blockchain ecosystem) to attest to cross-chain reads, enabling sub-second, authenticated cross-chain data retrieval. It currently supports querying, parsing, and verifying on all connected Wormhole EVM networks and Solana. Read more about Queries in the docs.

💡 The Queries feature relevant for WorldID is support for requesting a designated eth_call from a given contract on Ethereum and the ability to parse and verify the response on Solana.

Ethereum → Solana Wormhole State Bridge Service

The Ethereum-to-Solana State Bridge Service is responsible for monitoring the World ID contract on Ethereum for state root changes and propagating the root to Solana. It can do this by performing the following steps:

Subscribe to TreeChanged events or poll for latestRoot.
1. event TreeChanged(uint256 indexed preRoot, TreeChange indexed kind, uint256 indexed postRoot);
When the root has updated, issue a Wormhole Query request for the latestRoot on Ethereum.
Submit the Query response to the SolanaWorldID program on Solana.

This is akin to the EVM L2 State Bridge Service

Design

The bridge service provided in /app is a TypeScript program designed to be run either in a scheduled lambda / cloud function setting or as a service. If the SLEEP environment variable is set, it will run as a service, sleeping for SLEEP seconds between calls and will not exit on errors, otherwise it will simply run once, throwing on errors. When running as a service, the CLEANUP environment variable may also be set, which works the same as SLEEP but for cleaning up expired roots, reclaiming their rent.

Testing

Localnet Mock

Optionally, change the following line in solana-world-id-program.ts from it to it.only:

  it(fmtTest("initialize", "Successfully initializes"), async () => {

Run the following to start a local validator:

anchor test --detach

Finally, run

NETWORK=localnet npm start

Running NETWORK=localnet npm start subsequent times will update the root again, as necessary.

Testnet Mock

Akin to the above but

anchor test --detach -- --no-default-features --features testnet

and

NETWORK=testnet MOCK=true SOLANA_RPC_URL="http://127.0.0.1:8899" WALLET="../tests/keys/pFCBP4bhqdSsrWUVTgqhPsLrfEdChBK17vgFM7TxjxQ.json" npm start

Wormhole Testnet / Solana Devnet

NETWORK=testnet WALLET=~/.config/solana/your-key.json QUERY_API_KEY=your-wormhole-query-api-key npm start