How to get request digest value from provider hosted app?
I am developing SharePoint 2013 Provider hosted app using javascript REST Api. In order to perform create (POST), or update (MERGE) operations on sharepoint items I need to set the 'X-RequestDigest' header with the request. When in SharePoint-hosted apps I was able to use the http://contoso.sharepoint.com/SharePointHostedApp/_api/contextinfo service to retrieve the request digest value; however, I am having trouble getting that value when in a provider hosted app. The first difference of provider hosted app is that now we need to make a cross-domain request since we are not running in a