SharepointOnlineCredentials not working in an app

Question

I want to authenticate against sharepoint online site using SharepointOnlineCredentials class. Below code works fine in a console application. But the same code is generating error when written in wcf data service and consumed in a provider hosted app.

  ClientContext clientContext = new ClientContext("<Sharepoint online site url>");
  SecureString securePassword = new SecureString();
  foreach (char c in _password)
  {
      securePassword.AppendChar(c);
  }
  //Generates exception on this step. Exception details provided below
  SharePointOnlineCredentials creds = new SharePointOnlineCredentials(_username, securePassword);
  clientContext.Credentials = creds;

Exception Details:

Catastrophic failure (Exception from HRESULT: 0x8000FFFF (E_UNEXPECTED))

at Microsoft.SharePoint.Client.Idcrl.ManagedIdcrl.CheckHResult(Int32 hr) at Microsoft.SharePoint.Client.Idcrl.ManagedIdcrl.EnsureInited() at Microsoft.SharePoint.Client.Idcrl.ManagedIdcrl.LogonIdentity(String username, SecureString password) at Microsoft.SharePoint.Client.Idcrl.SharePointOnlineAuthenticationProvider.Logon(String username, SecureString password) at Microsoft.SharePoint.Client.SharePointOnlineCredentials..ctor(String username, SecureString password)

Answer 1

The way the SharePointOnlineCredentials must be used differ from a client app versus web service - i believe this example explains it http://tomaszrabinski.pl/wordpress/2013/03/18/connecting-to-office-365-using-client-side-object-model-and-web-services/