Discussion: Legacy 1271 Support (to enable signing on a Safe)

[jamesmccomish]

The current smart wallet ERC1271 setup does not allow the account to be used as a signer on a Safe.

Safe check contract signatures using the legacy ERC1271 function:
isValidSignature(bytes,bytes). So they expect the legacy return value of 0x20c13b0b.

Since it's a pretty minimal addition which would enable the smart wallet to be used with the most popular multisig, I added the legacy isValidSignature function on this test branch.

Do you think it's something worth keeping in the code?

[wilsoncusack]

Hey thanks for this. Interesting! I wasn't aware of this legacy value. Is there some ERC history?

[jamesmccomish]

It's strange that there isn't any mention of it in the ERC itself given it's still in production on some contracts. But the git history of EIP1271 shows the legacy value here.

Maybe it never got finalised with that value? But I have seen it used in a few contracts, and Safe signers are a pretty big use case.