Explanation

Adds new eth_getPlumeSignature RPC method that implements a novel ECDSA nullifier scheme.

The eth_getPlumeSignature method takes in two parameters, a message and an address, then generates a deterministic signature (plume) and several other inputs. The plume can be used as a nullifier to prevent double-spending in an anonymity set. This capability unlocks novel on-chain behavior, such as private DAO voting, fair, non-doxxing airdrops, and more.

Screenshots/Screencaps

Before

RPC method did not exist!

After

Manual Testing Steps

After building and running MetaMask locally, enter this into the browser console

window.ethereum.request({
    method: 'eth_getPlumeSignature',
    params: [
        'this is a message to sign',
        '<YOUR ETHEREUM ADDRESS>'
    ]
})
    .then(data => console.log(data))

A confirmation screen should open up. After clicking confirm, you will see the plume and other signals outputted into the console.

See screen capture above for more details.

Pre-merge author checklist

• I've clearly explained:
  • What problem this PR is solving
  • How this problem was solved
  • How reviewers can test my changes
• Sufficient automated test coverage has been added

Pre-merge reviewer checklist

• Manual testing (e.g. pull and build branch, run in browser, test code being changed)
• PR is linked to the appropriate GitHub issue
• IF this PR fixes a bug in the release milestone, add this PR to the release milestone

If further QA is required (e.g. new feature, complex testing steps, large refactor), add the Extension QA Board label.

In this case, a QA Engineer approval will be be required.