(EIP712) - Encoding TypedData containing bytes

[fdematos]

I want to encode the following typed message:

{
  "types": {
      "EIP712Domain": [
          {"name": "verifyingContract", "type": "address"},
          {"name": "chainId", "type": "uint256"},
      ],
      "TxMessage": [
          {"name": "signer", "type": "address"},
          {"name": "to", "type": "address"},
          {"name": "data", "type": "bytes"},
          {"name": "nonce", "type": "uint256"}
      ]
  },
  "primaryType": "TxMessage",
  "domain": {
      "chainId": 3,
      "verifyingContract": "0x9f733Fd052A5526cdc646E178c684B1Bf2313C57"
  },
  "message": {
      "signer": "0x2c68bfBc6F2274E7011Cd4AB8D5c0e69B2341309",
      "to": "0x68f3cEdf21B0f9ce31AAdC5ed110014Af5DA1828",
      "data": "0xa21f3c6a68656c6c6f000000000000000000000000000000000000000000000000000000776f726c64202100000000000000000000000000000000000000000000000000",
      "nonce": 0
    }
}

Calling :

let typedData = try! JSONDecoder().decode(TypedData.self, from: jsonString.data(using: .utf8)!)
try! typedData.signableHash().web3.hexString

Returns:

0x064198dd39fd7731b32f3ea8873c8811a58d0a161374a7755533f67c8fb3c7fa

Expected returns:

0x1f177092c4fbedf53f392389d4512f0a61babf07acc05303a4f1ef7e90b67d92

Fix proposal

I thinks the problem come from the method parseAtomicType on the file Utils/TypedData.swift.

You have line 110:

       case .DynamicString, .DynamicBytes:
            guard let value = data.stringValue?.web3.keccak256 else {
                throw ABIError.invalidValue
            }
            return try ABIEncoder.encode(value, forType: .FixedBytes(32))
        case .FixedAddress, .FixedBytes:

You are considering 0xa21f3c6a68656c6c6f000000000000000000000000000000000000000000000000000000776f726c64202100000000000000000000000000000000000000000000000000" as a String, not as a Hex encoded Data.

I think it should be:

case .DynamicBytes:
            guard let stringValue = data.stringValue, let value = Data(hex:stringValue)?.web3.keccak256 else {
                throw ABIError.invalidValue
            }
            return try ABIEncoder.encode(value, forType: .FixedBytes(32))
        case .DynamicString:
            guard let value = data.stringValue?.web3.keccak256 else {
                throw ABIError.invalidValue
            }
            return try ABIEncoder.encode(value, forType: .FixedBytes(32))

Using this code, I got the expected Hash.

I think you based your code from TrustCore iOS SDK because it has the same logic with the same issues.

Thanks

[DarthMike]

Hello @fdematos, I'll take a look today. Thank you for reporting the issue.

[DarthMike]

Issue is now fixed and published in 0.4.1