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Send a transaction with viem

Mera exports an adapter function toViemAccount that adapts a signing session into the account shape viem accepts, so viem signs and broadcasts while the key is owned by the session.

Sign in

Section titled “Sign in”
import { getPasskeyPrfOutput } from "@category-labs/mera";


const rpId = location.hostname;


const { prfOutput } = await getPasskeyPrfOutput({ rpId });

Derive the key

Section titled “Derive the key”

The seed and path come from the same mapping Create passkey accounts uses (Keys and accounts introduces the standards).

import { HDKey } from "@scure/bip32";
import { entropyToMnemonic, mnemonicToSeedSync } from "@scure/bip39";
import { wordlist } from "@scure/bip39/wordlists/english.js";


const firstEthereumAccountPath = "m/44'/60'/0'/0/0";


const seed = mnemonicToSeedSync(entropyToMnemonic(prfOutput, wordlist));


const node = HDKey.fromMasterSeed(seed).derive(firstEthereumAccountPath);
if (node.privateKey === null) throw new Error("derivation produced no key");

Create the viem account

Section titled “Create the viem account”

toViemAccount lives in the @category-labs/mera/viem entry point, which requires the optional viem peer dependency.

import { createSecp256k1SigningSession } from "@category-labs/mera";
import { toViemAccount } from "@category-labs/mera/viem";


const session = createSecp256k1SigningSession({
  privateKey: node.privateKey,
});


const account = toViemAccount(session);

Send the transaction

Section titled “Send the transaction”
import { createWalletClient, http, parseEther } from "viem";
import { sepolia } from "viem/chains";


const client = createWalletClient({
  account,
  chain: sepolia,
  transport: http(),
});


const recipient = "0x70997970C51812dc3A010C7d01b50e0d17dc79C8";
const hash = await client.sendTransaction({
  to: recipient,
  value: parseEther("0.01"),
});


session.end();

sendTransaction fills the missing transaction fields from the RPC, signs through the session and broadcasts.

See also

Section titled “See also”