dgf-prototype/backend/src/verify-signature.js

const { recoverPersonalSignature } = require('@metamask/eth-sig-util');

const verifySignature = ({
  authors, content, signature, embeddedData,
}) => {
  let contentToVerify = content;
  if (embeddedData && Object.entries(embeddedData).length) {
    contentToVerify += `\n\n${JSON.stringify(embeddedData, null, 2)}`;
  }
  try {
    const account = recoverPersonalSignature({ data: contentToVerify, signature });
    const authorAddresses = authors.map((author) => author.authorAddress.toLowerCase());
    if (!authorAddresses.includes(account.toLowerCase())) {
      console.log('error: signer is not among the authors');
      return false;
    }
  } catch (e) {
    console.log('error: failed to recover signature:', e.message);
    return false;
  }
  return true;
};

module.exports = verifySignature;