Office 365 Sharepoint Default Credentials

Question

I am trying to update an internal application that updates a SharePoint list to be able to authenticate using the users current credentials to Office 365 SharePoint. I keep getting a error "The remote server returned an error: (401) Unauthorized." Does Office 365 SharePoint not support CredentialCache?

Here is a simple example that I am trying.

    static void Main(string[] args)
    {
        ConsoleColor defaultForeground = Console.ForegroundColor;
        Console.ForegroundColor = ConsoleColor.Green;
        //Office 365 Site URL
        string webUrl = "https://sp_site.sharepoint.com/";

        using (var newlistitem = new ClientContext(webUrl))
        {
            //newlistitem.Credentials = new SharePointOnlineCredentials(userName, password); works
            newlistitem.AuthenticationMode = ClientAuthenticationMode.Default;
            newlistitem.Credentials = CredentialCache.DefaultNetworkCredentials; 
            //Also tried just DefaultCredentials - same error
            List spList = newlistitem.Web.Lists.GetByTitle("List1");
            ListItemCreationInformation itemCreateInfo = new ListItemCreationInformation();
            ListItem newItem = spList.AddItem(itemCreateInfo);
            newlistitem.Load(spList);
            newItem["Title"] = "Test1";
            newItem.Update();

            newlistitem.ExecuteQuery();

        }
    }

Answer 1

For Local, by default the managed client object models authenticate users by using their Windows credentials (DefaultCredentials).So you don't need to explicitly set the Credentials for local.

But for Office 365, you have to pass the credentials:

context = new ClientContext(siteURL);
SecureString spassWord = new SecureString();
foreach (char c in password.ToCharArray()) spassWord.AppendChar(c);

context.Credentials = new SharePointOnlineCredentials(userName, spassWord);
web = context.Web;
context.Load(web);

context.ExecuteQuery();