Extension support for hardware wallets

[PatrickAlphaC]

Component

Forge

Describe the feature you would like

Foundry right now only has support for Leger or Trezor. This limits a developers options for working with hardware wallets, and promotes one of two options:

1. Export private keys for deployments
2. Use one of the supported wallets

If a user exports their private keys, they now increase the risk of that key being compromised. Ideally the keys stay in the hardware wallets. However, if I user doesn't have one of the supported wallets, they feel compelled to expose the private keys. Ideally, they are not using those keys to have privileged access, but it still enforces a bit of a bad practice.

My initial idea to fix this would be to enable support for metamask/software wallet, as those are already compatible with many hardware devices, and making Foundry compatible with Metamask would, in essence, leveraged the compatibilities there to make essentially any hardware wallet compatible, but it seems this feature is undesired.

#10823 (comment)

So, instead, having a system that enables devs to add a "plug-in" feature for hardware wallets is another recommended path, hence the issue created here.

Additional context

Related: #6556

[zerosnacks]

Thanks for your suggestion!

In my opinion our "plug-in" feature is effectively the signer-* crates in Alloy: https://github.com/alloy-rs/alloy/tree/main/crates. Ledger is supported through https://github.com/summa-tx/coins and Trezor through https://crates.io/crates/trezor-client.

What are specific hardware wallets you would like to see supported? Anything implemented in Alloy can be easily supported in Foundry.

Ideally, they are not using those keys to have privileged access, but it still enforces a bit of a bad practice.

I feel like single-use keystores are a good middle ground for users for things like repeated testnet deployments / testnet interactions. Deployment accounts should never be privileged post-execution and it is clear user error if they do so in production settings.

We should review https://getfoundry.sh/guides/best-practices/key-management for its accuracy and latest best practices

[zzh1996]

@zerosnacks

What are specific hardware wallets you would like to see supported?

I must stress that supporting third-party hardware wallets beyond just Ledger and Trezor is absolutely necessary. While these two are the most well-known, they have a critical flaw: they don't display the complete transaction parameters, often forcing users to "blind sign". (This is precisely one of the major reasons for the Bybit hack.)

The top priority should be to support QR-based hardware wallets based on EIP-4527. This approach already has wide adoption. MetaMask currently uses it to support Keystone, AirGap Vault, CoolWallet, D'Cent, ImToken, OneKey, and Ngrave Zero. Integrating this would not only cover the vast majority of other hardware wallets but also allow professional users to properly verify all transaction parameters by scanning QR codes.

Deployment accounts should never be privileged post-execution and it is clear user error if they do so in production settings.

On the topic of deployer keys, I see the technical point, but I believe exposing private keys is too risky from a business perspective. Consider this scenario: the private key for an official deployer address, like an address labeled "Uniswap: Deployer" on Etherscan, gets compromised. It could be used to deploy scam ERC-20 or NFT contracts, sign or post malicious on-chain messages, or interact with other projects, even competitors. Even without direct financial loss from the original contract, the damage to the project's reputation would be unacceptable. This risk goes beyond technical best practices and into crucial operational security.