Sign and verify arbitrary payloads

[CodeSandwich]

Component

Cast

Describe the feature you would like

We can sign and verify messages using cast wallet sign, they get the \x19Ethereum Signed Message:\n prefix before being hashed. It'd be great to be able to do the same with arbitrary payloads.

This could be used to tinker around with all kinds of signed things:

• ERC-712 messages. Currently there's no way to create or verify a permit payload.
• Raw transactions. There's no way to verify an arbitrary supposedly signed transaction. There's also no way to manually build a transaction because it can't be signed.

It's crucial to be able to provide a raw 256-bit payload (hash) to be signed. Being able to provide a payload which needs to be hashed first would be a nice addition, but not necessary, it'd save a call to cast keccak.

Additional context

No response

[onbjerg]

Maybe we should add a flag like --raw or --headerless?

[CodeSandwich]

That would be awesome, --raw could accept a 256-bit payload to be directly signed and --headerless an arbitrary length payload to be hashed and then signed.

[raxhvl]

Raw transactions. There's no way to verify an arbitrary supposedly signed transaction. There's also no way to manually build a transaction because it can't be signed.

I am looking to use cast for this use case. Any luck this would work?

[marcuspang]

Hey @CodeSandwich, I implemented the --raw and --headerless flags as mentioned over at #5248. I also added a --raw flag for cast wallet verify. Is this what you had in mind for the feature?

[CodeSandwich]

Hi @marcuspang, yes, that's exactly it!

[marcuspang]

I believe this issue is resolved with #7180 using the --no-hash flag. Although one would need to hash the message themselves first.