如何使用 Mera 创建 passkey 账户

npm install @category-labs/mera viem @scure/bip32 @scure/bip39

import { createPasskeyWithPrfOutput } from "@category-labs/mera";

const created = await createPasskeyWithPrfOutput({
  rp: { id: location.hostname, name: "My Monad App" },
  user: { name: "player@example.com", displayName: "Player One" },
});

// created.prfOutput — Uint8Array(32), the root of every account
localStorage.setItem(
  "app.credential",
  JSON.stringify({
    credentialId: created.credentialId,
    transports: created.transports,
  }),
);

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

function deriveEvmKey(prfOutput: Uint8Array, index = 0): Uint8Array {
  const seed = mnemonicToSeedSync(entropyToMnemonic(prfOutput, wordlist));
  const node = HDKey.fromMasterSeed(seed).derive(`m/44'/60'/0'/0/${index}`);
  if (node.privateKey === null) throw new Error("derivation produced no key");
  return node.privateKey;
}

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

const session = createSecp256k1SigningSession({
  privateKey: deriveEvmKey(created.prfOutput),
});

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

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

session.end();

import { getPasskeyPrfOutput } from "@category-labs/mera";

const stored = localStorage.getItem("app.credential");
const known = stored ? JSON.parse(stored) : undefined;

const { prfOutput, credentialId } = await getPasskeyPrfOutput({
  rpId: location.hostname,
  credential: known,
});

// Nothing stored? The browser may have used a different passkey, so record it.
localStorage.setItem(
  "app.credential",
  JSON.stringify(known?.credentialId === credentialId ? known : { credentialId }),
);

// src/lib/wallet.ts
import {
  createSecp256k1SigningSession,
  getPasskeyPrfOutput,
  type Secp256k1SigningSession,
} from "@category-labs/mera";
import { toViemAccount } from "@category-labs/mera/viem";
import { createWalletClient, http, parseEther, type Hex } from "viem";
import { monadTestnet } from "viem/chains";

let session: Secp256k1SigningSession | undefined;

export async function connect() {
  const stored = localStorage.getItem("app.credential");
  const { prfOutput } = await getPasskeyPrfOutput({
    rpId: location.hostname,
    credential: stored ? JSON.parse(stored) : undefined,
  });

  session = createSecp256k1SigningSession({
    privateKey: deriveEvmKey(prfOutput),
  });

  return toViemAccount(session).address;
}

export function send(to: Hex, mon: string) {
  if (!session) throw new Error("not connected");

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

  return client.sendTransaction({ to, value: parseEther(mon), gas: 21_000n });
}

export function disconnect() {
  session?.end();
  session = undefined;
}

export async function send(to: Hex, mon: string) {
  const stored = localStorage.getItem("app.credential");
  const { prfOutput } = await getPasskeyPrfOutput({
    rpId: location.hostname,
    credential: stored ? JSON.parse(stored) : undefined,
  });

  using session = createSecp256k1SigningSession({
    privateKey: deriveEvmKey(prfOutput),
  });

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

  return client.sendTransaction({ to, value: parseEther(mon), gas: 21_000n });
}

import { isMeraError } from "@category-labs/mera";

if (isMeraError(error)) {
  switch (error.code) {
    case "PRF_UNAVAILABLE":          // unsupported passkey provider
    case "PASSKEY_OPERATION_FAILED": // prompt dismissed or failed; offer a retry
    case "CRYPTO_UNAVAILABLE":       // not a secure context
    case "SESSION_ENDED":            // signing call after end()
  }
}