@Nikolay Mikheev This is very helpful, however, I cannot seem to get this to work. I can get this to work in Postman just fine. I define the Region and Service Name and the request goes through just fine. However, ServiceNow will generate an Authorization token to use, but when I use it in a request it doesn't work, it returns 

var method = 'GET';
var service = 'nsm-service';
var region = 'us-west-2';
var credentialSID = '6db9679347c39d10ff7ca904846d4341'; 
var gdt = new GlideDateTime();

  // Define the HttpRequestData object
  var host = "nsm-service-corp.us-west-2.amazonaws.com";
  var endpoint = "https://" + host;
  var httpRequestData = new sn_auth.HttpRequestData();
  var dateNum = gdt.getNumericValue();

  httpRequestData.setEndpoint(endpoint);
  httpRequestData.setHost(host);
  httpRequestData.setRegion(region);
  httpRequestData.setService(service);
  httpRequestData.setHttpMethod(method);
  httpRequestData.setDate(dateNum);
    // httpRequestData.addQueryParam('Action', 'ListUsers'); //we don't use any params
    // httpRequestData.addQueryParam('Version', '2010-05-08'); //we don't use any params

  var credential = (new sn_cc.StandardCredentialsProvider()).getAuthCredentialByID(credentialSID);
  // Create the RequestAuthAPI object and sign the request
  var signingAPI = new sn_auth.RequestAuthAPI(httpRequestData, credential);
  var signMessage = signingAPI.generateAuth();  
  gs.log("Status is: " + signMessage.getStatus());
 
  //------------------------------------------------------------------------
  var headerMap = signMessage.getHeaderMap();

  for(var x in headerMap) {
   var y = headerMap[x];
   gs.log('HeaderMap[' + x + ']: ' + y);
  }