try
{
       // Way safer than string comparison against "BUILTIN\\Administrators"
       IdentityReference BuiltinAdministrators = new SecurityIdentifier(WellKnownSidType.BuiltinAdministratorsSid, null);
       IdentityReference AuthenticatedUsers = new SecurityIdentifier(WellKnownSidType.AuthenticatedUserSid, null);

       FileSecurity FileACL = File.GetAccessControl("database.sdf"); // Grab ACL from file

       if (FileACL.GetOwner(typeof(SecurityIdentifier)) != BuiltinAdministrators) // Check if correct owner is set
       {
             FileACL.SetOwner(BuiltinAdministrators); // If not, make it so!
       }

       foreach (FileSystemAccessRule fsRule in FileACL.GetAccessRules(true, true, typeof(SecurityIdentifier)))
       {
             if ((fsRule.FileSystemRights & FileSystemRights.Delete) == FileSystemRights.Delete ||
                    (fsRule.FileSystemRights & FileSystemRights.ChangePermissions) == FileSystemRights.ChangePermissions) // Check if rule grants delete or change permissions
             {
                  FileACL.RemoveAccessRule(fsRule); // If so, nuke it!
             }
       }

       // Add explicit rules
       FileACL.AddAccessRule(new FileSystemAccessRule(BuiltinAdministrators, FileSystemRights.FullControl, AccessControlType.Allow));
       FileACL.AddAccessRule(new FileSystemAccessRule(AuthenticatedUsers, FileSystemRights.Delete, AccessControlType.Deny));
       FileACL.AddAccessRule(new FileSystemAccessRule(AuthenticatedUsers, FileSystemRights.ChangePermissions, AccessControlType.Deny));
       FileACL.AddAccessRule(new FileSystemAccessRule(AuthenticatedUsers, FileSystemRights.Read, AccessControlType.Allow));
       FileACL.AddAccessRule(new FileSystemAccessRule(AuthenticatedUsers, FileSystemRights.Write, AccessControlType.Allow));

       FileACL.SetAccessRuleProtection(true, false); // Enable protection from inheritance, remove existing inherited rules
       File.SetAccessControl("database.sdf", FileACL); // Write ACL back to file
   }
   catch { }