add `metamask` support

[PatrickAlphaC]

it would be great if someone could do like:

mox run deploy --metamask

And their browser pops up asking them to send a TX from their metamask instead of storing/saving a private key

[s3bc40]

I am curious about this. I'll try to learn from their doc and see if it is manageable!

[PatrickAlphaC]

@s3bc40 this would be actually so sick

[s3bc40]

I thought I let some comment here... But apparently not. I went other the Metamask doc, but there is no straightforward method.

But apparently the Metamask extension can capture a specific URL sent in the browser, so we could open it with a preprocessed URL in mox: https://docs.python.org/3/library/webbrowser.html.

I also saw some ideas about running a web server as a sub-process and "inject" some JS, but I am not convinced...

I need to test webbrowser after finishing extra things on my end 👍

[s3bc40]

So I tried to understand how to use this feature to avoid storing the private key locally. And AI was really helpfull to imagine a workflow for this.

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How it works

The Moccasin CLI would prepare the unsigned transaction data (with web3.py?). It then launches a minimal browser page (using a local temporary server) containing PyScript (or JS). This browser page directly interacts with MetaMask via window.ethereum.request, prompting the user for transaction confirmation.

Key Security Point:

MetaMask's core design never exposes private keys to the browser page or the CLI. All signing happens securely inside the MetaMask extension. The CLI would receive only the public account address or the transaction hash, never the private key itself.

The Trade-off:

Transaction Confirmation:
This is the central point to consider for multi-transaction deployments. If MetaMask handles signing, users will see a MetaMask pop-up for each individual transaction to confirm. This is MetaMask's inherent security feature, ensuring explicit user consent for every action. This provides the highest level of security by keeping the private key isolated.

In essence:

The feature is possible if you accept MetaMask prompting for each transaction to ensure maximum security.

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Does it seem close to the conception you had in mind @PatrickAlphaC ? I do not have the experience on this, though I see how it could be built. I just want to be sure that I have understood the assignment before diving too much.

[PatrickAlphaC]

This is in now!