Workaround to sign Recurly.js billing info updates

signbillinginfo.js

var crypto = require('crypto');

var privateKey = 'yourprivatekey';

function signBillingInfo(accountCode) {

  // copypasta from transparent post
  function hash(data) {
    //get the sha1 of the private key in binary
    var shakey = crypto.createHash('sha1');
    shakey.update(privateKey);
    shakey = shakey.digest('binary');
    //now make an hmac and return it as hex
    var hmac = crypto.createHmac('sha1', shakey);
    hmac.update(data);
    return hmac.digest('hex');
   }

  var timestamp = Math.round((new Date()).getTime() / 1000);

  var message = '['+timestamp+',billinginfoupdate,[';
  message += 'account_code:' + accountCode;
  message += ']]';

  return hash(message) + '-' + timestamp;
}

console.log( signBillingInfo('anaccountcode') );


/* backend:
 *
 * signature = signBillingInfo(accountCode);
 *
 * view: 
 *
 * buildBillingInfoUpdateForm({
 *   ...
 *   accountCode: '#{accountCode}'
 *   signature: '#{signature}'
 * });
 * */