如何在 React Native 中使用 Mera

import { getRandomValues } from "expo-crypto";

if (typeof globalThis.crypto?.getRandomValues !== "function") {
  Object.defineProperty(globalThis, "crypto", {
    configurable: true,
    value: { ...globalThis.crypto, getRandomValues },
  });
}

import "./src/polyfills";

import { registerRootComponent } from "expo";
import App from "./App";

registerRootComponent(App);

import type { ExpoConfig } from "expo/config";

const rpId = "accounts.example.com";

const config: ExpoConfig = {
  name: "My Monad App",
  slug: "my-monad-app",
  ios: {
    bundleIdentifier: "com.example.app",
    associatedDomains: [`webcredentials:${rpId}`],
  },
  android: {
    package: "com.example.app",
  },
  extra: { rpId },
};

export default config;

import {
  createPasskeyWithPrfOutput,
  getPasskeyPrfOutput,
} from "@category-labs/mera";
import { reactNativeWebAuthnClient } from "@category-labs/mera/react-native-webauthn-client";

const rpId = "accounts.example.com";

export function createAccount() {
  return createPasskeyWithPrfOutput({
    rp: { id: rpId, name: "My Monad App" },
    user: { name: "player@example.com", displayName: "Player One" },
    webAuthnClient: reactNativeWebAuthnClient,
  });
}

export function signIn() {
  return getPasskeyPrfOutput({
    rpId,
    webAuthnClient: reactNativeWebAuthnClient,
  });
}

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

export function deriveEvmKey(
  prfOutput: Uint8Array,
  index = 0,
): Uint8Array {
  const mnemonic = entropyToMnemonic(prfOutput, wordlist);
  const seed = mnemonicToSeedSync(mnemonic);
  try {
    const node = HDKey.fromMasterSeed(seed).derive(`m/44'/60'/0'/0/${index}`);

    if (node.privateKey === null) {
      throw new Error("Derivation produced no private key");
    }

    return node.privateKey;
  } finally {
    seed.fill(0);
  }
}

import { createSecp256k1SigningSession } from "@category-labs/mera";
import { toViemAccount } from "@category-labs/mera/viem";
import { createWalletClient, http, parseEther } from "viem";
import { monadTestnet } from "viem/chains";
import { signIn } from "./passkey";
import { deriveEvmKey } from "./wallet";

export async function sendTransaction() {
  const { prfOutput } = await signIn();
  const privateKey = deriveEvmKey(prfOutput);
  const session = createSecp256k1SigningSession({ privateKey });

  try {
    const client = createWalletClient({
      account: toViemAccount(session),
      chain: monadTestnet,
      transport: http(),
    });

    const hash = await client.sendTransaction({
      to: "0x70997970C51812dc3A010C7d01b50e0d17dc79C8",
      value: parseEther("0.01"),
      gas: 21_000n,
    });

    return hash;
  } finally {
    privateKey.fill(0);
    prfOutput.fill(0);
    session.end();
  }
}