ChainId of TypedDataDomain not serializable during JsonRpcSigner.signTypedData()

[ZirionNeft]

Ethers Version

6.0.8

Search Terms

bigint, chainId, JsonRpcSigner, signTypedData, json, serialize, stringify

Describe the Problem

When trying to jsonRpcSigner.signTypedData(...) I got an error:

TypeError: Do not know how to serialize a BigInt
    at JSON.stringify (<anonymous>)
    at JsonRpcSigner.signTypedData (provider-jsonrpc.ts:324:18)

After debugging I realize that chainId of Domain data type converts to bigInt during TypedDataEncoder.getPayload(...), but after that JSON.stringify() don't know how to work with them without second argument function.

Code Snippet

export const Domain = (address: string, chainId: bigint) => ({
	name: 'EtherAlertsDonations',
	version: '1',
	chainId: '0x' + chainId.toString(), // or variable with any other type - nevermind
	verifyingContract: address
});

export async function getDonationSig<Signer extends AbstractSigner>(
	signer: Signer,
	rawData: TDonationToSign,
	contract: string,
	chainId: bigint
) {
	return signer.signTypedData(Domain(contract, chainId), DonationType, rawData);
}

Contract ABI

No response

Errors

TypeError: Do not know how to serialize a BigInt
    at JSON.stringify (<anonymous>)
    at JsonRpcSigner.signTypedData (provider-jsonrpc.ts:324:18)

### Environment

Ethereum (mainnet/ropsten/rinkeby/goerli), node.js (v12 or newer), Browser (Chrome, Safari, etc), Other (please specify)

### Environment (Other)

Svelte, SvelteKit

[Jovonni]

consistently getting this when signing:

 TypeError: Do not know how to serialize a BigInt

should I download until a fix, or is there a current workaround? @ZirionNeft @ricmoo

[insulineru]

Same problem with ethers@6.1.0

const domain = {
    "name": "Transfer Money",
    "version": "1.0.0",
    "chainId": 137,
    "verifyingContract": "0x91a3129e96e9488a98db463177F9A1312CF22081"
}

const TypesTransfer = {
  TransferCall: [
    { name: 'token', type: 'address' },
    { name: 'to', type: 'address' },
    { name: 'amount', type: 'uint256' },
    { name: 'fee', type: 'uint256' },
    { name: 'nonce', type: 'uint256' }
  ]
}

const config = {
    "token": "0x2791Bca1f2de4661ED88A30C99A7a9449Aa84174",
    "to": "0x777777125C91be606997038d50aD039dD7caa1a3",
    "amount": "4000000",
    "fee": "0",
    "nonce": "12607236389627287883"
}
signer.signTypedData(domain, TypesTransfer, config)

[ZirionNeft]

@Jovonni My workaround is just re-implementation of Signer class with true JSON.stringify with replacer callback.

[ricmoo]

Thanks! I've confirmed it's a bug.

Quick question @ZirionNeft, if the value is outside the safe integer range, do you encode it as a 0x-prefixed quantity?

[insulineru]

@ricmoo I think you will find this information useful for the fix.

I made a patch like this to fix the problem

[ricmoo]

@insulineru Thanks! So, passing the chainId as a decimal string works then? The payload will look like: ...{"domain":{"chainId":"1234",...}}?

[insulineru]

@insulineru Thanks! So, passing the chainId as a decimal string works then? The payload will look like: ...{"domain":{"chainId":"1234",...}}?

No. I tried passing "137" or "0x87" in the chainId parameter, but TypedDataEncoder translates any value into BigInt. So I have to patch the BigInt class

[ricmoo]

Oh, I meant when data is passed directly to MetaMask. Basically, your above fix works?

I have a local copy working too. :)

[insulineru]

I tried Metamask and Rabby Wallet and my fix worked fine. Before that, with the exact same example, I signed all the messages in ethers@5.7.2, so yeah

Thanks for the heads up, @ricmoo :)

[ricmoo]

Sorry, the fix was mislabelled in the commit (see 50b74b8). This has been fixed in v6.3.0.

Closing now as fixed, but if you run into any problems, please re-open.

Thanks! :)