Need a centred headline in Beamer

Question

I have a presentation to put together and I need to specify the classification of each page (UNCLASSIFED) centred at the very top (above the Frametitle) and at the very bottom. I tried using \setbeamertemplate{headline}{UNCLASSIFIED}, for example, but all it does is stick the classification on the far left. When I add it within \begin{center}{}\end{center}, nothing happens. In either case, I get nothing for the footline.

\documentclass[t]{beamer}
\begin{document}
\section{Background:  The Problem}
\frame{
\setbeamertemplate{headline}
{
\begin{center}
{\bf UNCLASSIFIED} 
\end{center}
}
\frametitle{Background:  The Problem}
\begin{itemize}
{\small
\item stuff stuff stuff stuff stuff stuff stuff stuff stuff stuff stuff stuff;
\item stuff stuff stuff stuff stuff stuff stuff stuff stuff stuff stuff stuff;
\item stuff stuff stuff stuff stuff stuff stuff stuff stuff stuff stuff stuff;
\item stuff stuff stuff stuff stuff stuff stuff stuff stuff stuff stuff stuff;
\item stuff stuff stuff stuff stuff stuff stuff stuff stuff stuff stuff stuff;
\item stuff stuff stuff stuff stuff stuff stuff stuff stuff stuff stuff stuff;}
\end{itemize}
\setbeamertemplate{footline}
{
\begin{center}{\bf UNCLASSIFIED}
\end{center}
}
}
\end{document}

Answer 1

You could try something like this:

\documentclass[t]{beamer}

\defbeamertemplate{headline}{class}[1]{%
    \vskip5pt%
    \makebox[\paperwidth][c]{\textbf{#1}}%
}

\defbeamertemplate{footline}{class}[1]{%
    \vskip-3pt
    \begin{minipage}[t][2cm][t]{\paperwidth}
        \centering
        \textbf{#1}\\
    \end{minipage}
}

\begin{document}

    \setbeamertemplate{headline}[class]{unclassified}
    \setbeamertemplate{footline}[class]{unclassified}
    \begin{frame}
        \frametitle{Background:  The Problem}
        test
    \end{frame}

    \setbeamertemplate{headline}[class]{classified}
    \setbeamertemplate{footline}[class]{classified}
    \begin{frame}
        \frametitle{Background:  The Problem}
        test
    \end{frame}

\end{document}