Not being able to use passphrase signs

[iwaduarte]

I am trying to sign with a private Key string that I have encrypted ( for security reasons) and altough the function called by this sign could be using that feature (since crypto have built in) unfortunately is not there.

The bypass it is a ugly hack:
{ keypairId: 'id', privateKeyString: {privateKeyString, passphrase: 'password', toString: () =>privateKeyString} };

The function below work just fine, since the fine method allows to receive a keyObject with the passphrase in it.
https://nodejs.org/api/crypto.html#crypto_class_keyobject

_createPolicySignature(policy, privateKey) {
  var sign = crypto.createSign('RSA-SHA1');
  sign.update(policy.toJSON());

  return sign.sign(privateKey, 'base64');
}

The problem it is with the validation function itself that assumes that I am sending a string while I am sending a object (because I need the passphrase property)

More specifically:

function _getPrivateKey(params) {
  var privateKeyString = params.privateKeyString; 

  var newLinePattern = /\r|\n/;
  var lineBreakExists = newLinePattern.test(privateKeyString);
  if (!lineBreakExists) {
      throw new Error('Invalid private key string, must include line breaks');
  }

  return privateKeyString;
}

I guess it should use destructuring to get the variable inside the object. What are your thoughts on this?