// service side ctor
 public SspiSecurityTokenProvider(NetworkCredential credential, bool extractGroupsForWindowsAccounts, bool allowUnauthenticatedCallers)
 {
     _token = new SspiSecurityToken(credential, extractGroupsForWindowsAccounts, allowUnauthenticatedCallers);
 }
 // client side ctor
 public SspiSecurityTokenProvider(NetworkCredential credential, bool allowNtlm, TokenImpersonationLevel impersonationLevel)
 {
     _token = new SspiSecurityToken(impersonationLevel, allowNtlm, credential);
 }