// The message string will be UTF-8 encoded before signing.
// Hashing (e.g., Keccak256 for Ethereum, SHA256 for Bitcoin)
// is handled automatically by the Lit Protocol based on the selected chain.
const messageBytes = new TextEncoder().encode(messageToSign);

const signatures = await litClient.chain.raw.pkpSign({
  chain: "ethereum",
  signingScheme: "EcdsaK256Sha256",
  pubKey: pkpInfo.pubkey,
  authContext: authContext,
  toSign: messageBytes, // UTF-8 encoded message
});