How to use the pem.createPrivateKey function in pem

'Create 2048bit Private key': (test: any) => {
    pem.createPrivateKey(2048, (error: any, data: any) => {
      const key = (data && data.key || '').toString();
      test.ifError(error);
      test.ok(key);
      test.ok(key.match(/^\n*\-\-\-\-\-BEGIN RSA PRIVATE KEY\-\-\-\-\-\n/));
      test.ok(key.match(/\n\-\-\-\-\-END RSA PRIVATE KEY\-\-\-\-\-\n*$/));
      test.ok(key.trim().length > 1650 && key.trim().length < 1700);
      // test.ok(fs.readdirSync('./tmp').length === 0);
      test.done();
    });
  },

'Create CSR with own encrypted key': (test: any) => {
    var password = 'my:secure! "password\'s\nawesome';
    pem.createPrivateKey(2048, { cipher: 'des3', password: password }, (error: any, data: any) => {
      var key = (data && data.key || '').toString();

      pem.createCSR({
                      clientKey: key,
                      clientKeyPassword: password
                    }, (error: any, data: any) => {
        var csr = (data && data.csr || '').toString();
        test.ifError(error);
        test.ok(csr);
        test.ok(csr.match(/^\n*\-\-\-\-\-BEGIN CERTIFICATE REQUEST\-\-\-\-\-\n/));
        test.ok(csr.match(/\n\-\-\-\-\-END CERTIFICATE REQUEST\-\-\-\-\-\n*$/));

        test.equal(data && data.clientKey, key);

        test.ok(data && data.clientKey);
        // test.ok(fs.readdirSync('./tmp').length === 0);

function getNewKey(keyLen, callback) {
  // this function wants key len in bits, our config 
  // specified it in bytes, so multiply by 8
  pem.createPrivateKey(keyLen*8, function(err, key) {
    if (err) {
        console.log("key callback got an error");
        callback(err, null);
    } else {
        var tempKeyStr = "";
        var finalKey = "";
        
        // get rid of wrapping text and new lines
        var result = key.key.split("\n");
        for (var i = 1; i < (result.length-1); i++) {
            tempKeyStr += result[i];
        }

        //console.log("tempKeyStr len: %d\ntempKeyStr: %s\n", tempKeyStr.length, tempKeyStr);

        // decode the string

function checkServiceKey(cb) {
  try {
    fs.statSync(keyPath);
    var serviceKey = fs.readFileSync(keyPath);
    cb(null, serviceKey);
  } catch (e) {
    if (e.code === 'ENOENT') {
      // if key.pem not exist, generate the private key
      console.log("Create the service key 'config/key.pem'");
      pem.createPrivateKey(2048, function(e, keyData) {
        if (e) {
          cb(e);
        } else {
          fs.writeFile(keyPath, keyData.key, function(e) {
            cb(e, e || { newKey: true, keyData: keyData.key });
          });
        }
      });
    } else {
      cb(e);
    }
  }
}

function createPrivateKey(req, res, next){
    if (openSSLEnabled) {
        let options = getKeyOptions(req.body.options);
        pem.createPrivateKey(
            options.keyBitsize,
            options,
            function(err, privateKey){
                if(err){
                    return res.parcel.setStatus(400)
                        .setData(err)
                        .deliver();
                }
                return res.parcel.setStatus(200)
                    .setData(privateKey.key)
                    .deliver();
            }
        );
    } else {
        res.parcel.setStatus(400)
            .setMessage('Security options have not been properly configured')

tasks.push(function(cb){
                pem.createPrivateKey(keyOptions.keyBitsize, keyOptions, function(err, key){
                    csrOptions.clientKey = key.key;
                    cb(err);
                });
            });
        }