Python signing EIP-712 messages for blur.io

Question

The goal is to place a collection bid on blur.io in python. To access the Blur API I use https://rapidapi.com/openseatools/api/blur/.

To summarise the issue: I cannot manage to successfully sign a message (or get the same signature in python as in Metamask, using the same data).

The attempt:

values = message["signatures"][0]["signData"]["value"]

# 'message' types that differs from 'types' schema
values["tokenId"] = int(values["tokenId"])
values["amount"] = int(values["amount"])
values["price"] = int(values["price"])
values["expirationTime"] = int(values["expirationTime"], 16)
values["salt"] = int(values["salt"], 16)
values["extraParams"] = bytes(int(values["extraParams"], 16))
values["nonce"] = int(values["nonce"])

data = {
    "domain": message["signatures"][0]["signData"]["domain"],
    "message": values,
    "types": { 
    "EIP712Domain": [
        {"name": "name", "type": "string"},
        {"name": "version", "type": "string"},
        {"name": "chainId", "type": "uint256"},
        {"name": "verifyingContract", "type": "address"},
     ], 
     **message["signatures"][0]["signData"]["types"]
  },
  "primaryType": 'Order',
}

signature = Web3().eth.account.sign_message(
    encode_structured_data(data), 
private_key=self.wallet_credentials.private_key) 

With message being the response from a POST /v1/collection-bids/format.

You can test the process by visiting blur.io and posting a collection bid (and watching the format and submit requests).

---

The developer from rapidapi.com provided the following code to sign the message in JS. This code works fine, so the question could be: how to implement this function in python?

const signature = await wallet.signer._signTypedData(
      message.signData.domain,
      message.signData.types,
      message.signData.value,
    );

Answer 1

The error was here:

values["extraParams"] = bytes.fromhex(values["extraParams"][2:])

Answer 2

Have got some troubles when trying to run this code

 values = message["signatures"][0]["signData"]["value"]
             ~~~~~~~^^^^^^^^^^^^^^
TypeError: string indices must be integers, not 'str'

encode_structured_data is not defined

private_key=self.wallet_credentials.private_key):
self is not defined, wallet_credentials.private_key = Any