ViemLocalEip712Signer.md

ViemLocalEip712Signer

An Eip712Signer that is initialized with an Viem LocalACcount and can be used with Builders to sign Farcaster Messages.

Properties

Name	Type	Description
scheme	Uint8Array	Signature scheme used when signing messages

Constructors

static new ViemLocalEip712Signer

Usage

import { ViemLocalEip712Signer } from '@farcaster/hub-nodejs';
import { mnemonicToAccount } from 'viem/accounts';

const mnemonic = 'ordinary long coach bounce thank quit become youth belt pretty diet caught attract melt bargain';
const account = mnemonicToAccount(mnemonic);
const eip712Signer = new ViemLocalEip712Signer(account);

Parameters

Name	Type	Description
signer	Signer	A wallet instance

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Instance Methods

getSignerKey

Returns the 160-bit address in bytes.

Usage

const ethereumAddressResult = await eip712Signer.getSignerKey();
if (ethereumAddressResult.isOk()) {
  console.log(ethereumAddressResult.value);
}

Returns

Value	Description
HubAsyncResult<Uint8Array>	A HubAsyncResult containing the 160-bit address as a Uint8Array.

signMessageHash

Generates a 256-bit signature for a string input and returns the bytes.

Usage

import { blake3 } from '@noble/hashes/blake3';
import { randomBytes } from '@noble/hashes/utils';

const bytes = randomBytes(32);
const hash = blake3(bytes, { dkLen: 20 });
const signatureResult = await eip712Signer.signMessageHash(hash);
if (signatureResult.isOk()) {
  console.log(signatureResult.value);
}

Returns

Value	Description
HubAsyncResult<Uint8Array>	The 256-bit signature as a Uint8Array.

Parameters

Name	Type	Description
hash	Uint8Array	The 256-bit hash of the message to be signed.

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signVerificationEthAddressClaim

Generates a 256-bit signature for a VerificationClaim and returns the bytes.

Usage

import { FarcasterNetwork, hexStringToBytes, makeVerificationEthAddressClaim } from '@farcaster/hub-nodejs';

const blockHashHex = '0x1d3b0456c920eb503450c7efdcf9b5cf1f5184bf04e5d8ecbcead188a0d02018';
const blockHashBytes = hexStringToBytes(blockHashHex)._unsafeUnwrap(); // Safety: blockHashHex is known and can't error

const ethereumAddressResult = await eip712Signer.getSignerKey();

if (ethereumAddressResult.isOk()) {
  const claimResult = makeVerificationEthAddressClaim(
    1,
    ethereumAddressResult.value,
    FarcasterNetwork.DEVNET,
    blockHashBytes
  );

  if (claimResult.isOk()) {
    const verificationResult = await eip712Signer.signVerificationEthAddressClaim(claimResult.value);
    if (verificationResult.isOk()) {
      console.log(verificationResult.value);
    }
  }
}

Returns

Value	Description
HubAsyncResult<Uint8Array>	The 256-bit signature as a Uint8Array.

Parameters

Name	Type	Description
claim	VerificationEthAddressClaim	The body of the claim to be signed.

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signUserNameProofClaim

Generates a 256-bit signature for a UserNameProofClaim and returns the bytes.

Usage

import { makeUserNameProofClaim } from '@farcaster/hub-nodejs';

const claim = makeUserNameProofClaim({
  owner: '0x8773442740c17c9d0f0b87022c722f9a136206ed',
  name: 'farcaster',
  timestamp: Date.now(),
});

const signatureResult = await eip712Signer.signUserNameProofClaim(claim);
if (signatureResult.isOk()) {
  console.log(signatureResult.value);
}

Returns

Value	Description
HubAsyncResult<Uint8Array>	The 256-bit signature as a Uint8Array.

Parameters

Name	Type	Description
claim	UserNameProofClaim	The body of the claim to be signed.

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