Implementing signing directly

import canonicalize from 'canonicalize'; // Support JSON canonicalization
import crypto from 'crypto'; // Support P-256 signing

// Replace this with your private key from the Dashboard
const PRIVY_AUTHORIZATION_KEY = 'wallet-auth:insert-your-private-key-here';
// ...

function getAuthorizationSignature({url, body}: {url: string; body: object}) {
  const payload = {
    version: 1,
    method: 'POST',
    url,
    body,
    headers: {
    'privy-app-id': 'insert-your-app-id'
    // If your request includes an idempotency key, include that header here as well
    }
  };

  // JSON-canonicalize the payload and convert it to a buffer
  const serializedPayload = canonicalize(payload) as string;
  const serializedPayloadBuffer = Buffer.from(serializedPayload);

  // Replace this with your user or authorization key. We remove the 'wallet-auth:' prefix
  // from authorization keys before using it to sign requests
  const privateKeyAsString = PRIVY_AUTHORIZATION_KEY.replace('wallet-auth:', '');

  // Convert your private key to PEM format, and instantiate a node crypto KeyObject for it
  const privateKeyAsPem = `-----BEGIN PRIVATE KEY-----\n${privateKeyAsString}\n-----END PRIVATE KEY-----`;
  const privateKey = crypto.createPrivateKey({
    key: privateKeyAsPem,
    format: 'pem'
  });

  // Sign the payload buffer with your private key and serialize the signature to a base64 string
  const signatureBuffer = crypto.sign('sha256', serializedPayloadBuffer, privateKey);
  const signature = signatureBuffer.toString('base64');
  return signature;
}

const authorizationSignature = getAuthorizationSignature({
  // Replace with your desired path
  url: 'https://api.privy.io/v1/wallets/<wallet_id>/rpc',
  // Replace with your desired body
  body: {
    method: 'personal_sign',
    params: {
    message: 'Hello world',
      // ...
    },
  }
});