Generate mailgun email signature in node.js

mailgun-signature-generator.js

var crypto = require('crypto');

var mailgunSignature = function(mailgunApiKey) {

  var token = crypto.randomBytes(25).toString('hex');
  var timestamp = Math.floor(Date.now() / 1000);

  return {
    token: token,
    timestamp: timestamp,
    signature: crypto
      .createHmac('sha256', mailgunApiKey)
      .update(new Buffer(timestamp + token, 'utf-8'))
      .digest('hex')
  };
};