Eip 1271 support

[q9f]

https://eips.ethereum.org/EIPS/eip-1271

[q9f]

Ref spruceid/siwe-ruby#15

[q9f]

Hi there, checking in on the status of this PR (#68), would be very helpful to implement EIP-1271 for Sign-In with Ethereum spruceid/siwe-ruby#15, let me know if there is anything I can do to help!

@w4ll3 I'm tracking EIP-1271 here, let's briefly discuss this. I'm not very familiar with the mechanics of 1271 but will you require full smart-contract support as in ethereum.rb gem? @kurotaky is working on that but it might take a couple of weeks to release this.

It's quite probable that 1271 does only require a subset of the functionality of that PR #68. Could you describe in a few bullet points what the 1271 authentication workflow looks like, so I can take a look? Maybe we can prioritize this specific feature.

[w4ll3]

Sure, 1271 defines a function that should be implemented on smart contract wallets, isValidSignature(hash, signature), so in order to support it we would need support to make a call using this ABI, you can see a Typescript implementation of it here https://github.com/spruceid/siwe/blob/main/packages/siwe/lib/utils.ts Att, Gregório Granado Magalhães.

…

On Mon, Apr 25, 2022, 1:24 PM Afr Schoe ***@***.***> wrote: Hi there, checking in on the status of this PR (#68 <#68>), would be very helpful to implement EIP-1271 for Sign-In with Ethereum spruceid/siwe-ruby#15 <spruceid/siwe-ruby#15>, let me know if there is anything I can do to help! @w4ll3 <https://github.com/w4ll3> I'm tracking EIP-1271 here, let's briefly discuss this. I'm not very familiar with the mechanics of 1271 but will you require full smart-contract support as in ethereum.rb gem? @kurotaky <https://github.com/kurotaky> is working on that but it might take a couple of weeks to release this. It's quite probable that 1271 does only require a subset of the functionality of that PR #68 <#68>. Could you describe in a few bullet points what the 1271 authentication workflow looks like, so I can take a look? Maybe we can prioritize this specific feature. — Reply to this email directly, view it on GitHub <#44 (comment)>, or unsubscribe <https://github.com/notifications/unsubscribe-auth/ACBSTQCOD5N52HCHWPXXZB3VG3BKJANCNFSM5LYGLIOA> . You are receiving this because you were mentioned.Message ID: <q9f/eth. ***@***.***>

[q9f]

Gotcha.

// SPDX-License-Identifier: Apache-2.0

pragma solidity ^0.8;

library LibBytes {
  function readBytes32(
    bytes memory b,
    uint256 index
  )
    internal
    pure
    returns (bytes32 result)
  {
    index += 32;
    require(b.length >= index);
    assembly {
      result := mload(add(b, index))
    }
    return result;
  }
}

contract Signer {
  using LibBytes for bytes;
  address constant internal OWNER = 0xCaA29806044A08E533963b2e573C1230A2cd9a2d;
  bytes4 constant internal MAGIC_VALUE = 0x1626ba7e;

  function isValidSignature(
    bytes32 _hash,
    bytes calldata _signature
  )
    external
    pure
    returns (bytes4)
  {
    if (recoverSigner(_hash, _signature) == OWNER) {
      return MAGIC_VALUE;
    } else {
      return 0xffffffff;
    }
  }

  function recoverSigner(
    bytes32 _hash,
    bytes memory _signature
  )
    internal
    pure
    returns (address signer)
  {
    require(_signature.length == 65);
    uint8 v = uint8(_signature[64]);
    bytes32 r = _signature.readBytes32(0);
    bytes32 s = _signature.readBytes32(32);
    signer = ecrecover(keccak256(abi.encodePacked("\x19Ethereum Signed Message:\n32", _hash)), v, r, s);
    return signer;
  }
}