XeroPrivate.gs needs PLAINTEXT oauth signature method but RSA-SHA1 encoded consumer secret about apps-script-oauth1

[jyauxi]

I've solved the problem, and it is not what I had written in the previous issue. The problem is in passing a proper PEM key. Two things should be noted:

1. Generating the key in the proper format - Using openssl generating a key for RSA-SHA1 is as follows:

openssl genrsa -out rsa-private-key.pem 1024

This generates a key rsa-private-key.pem with header:

-----BEGIN RSA PRIVATE KEY-----

This is the format that will NOT be accepted by computeRsaSignature(algorithm, value, key) function and must be converted to pkcs8 format with openssl and this command:

openssl pkcs8 -topk8 -inform pem -in rsa-private-key.pem -outform pem -nocrypt -out private-key.pem

The output private-key.pem should start with:

-----BEGIN PRIVATE KEY-----

2. Passing the key in the format required - the approach I used is to ask the user for the private key from a ui.prompt without the -----BEGIN PRIVATE KEY-----, and then when storing the key in PropertiesService, the -----BEGIN PRIVATE KEY-----\n and \n-----END PRIVATE KEY-----\n is appended.

/**
 * Dialog box to enter private key.
 */
function enterPrivateKey() {
  var ui = SpreadsheetApp.getUi();
  var result = ui.prompt("Enter private key", ui.ButtonSet.OK_CANCEL);
  // Process the user's response.
  var button = result.getSelectedButton();
  if (button == ui.Button.OK) { // User clicked "OK".
    var scriptProperties = PropertiesService.getScriptProperties();
    scriptProperties.setProperty("PRIVATE_KEY", "-----BEGIN PRIVATE KEY-----\n" + result.getResponseText() + "\n-----END PRIVATE KEY-----\n");
    ui.alert("private key saved");
  } else if (button == ui.Button.CANCEL) { // User clicked "Cancel".
    ui.alert("Private key was not saved");
  } else if (button == ui.Button.CLOSE) { // User clicked X in the title bar.
    ui.alert("You closed the dialog.");
  }
}