% File              : andrew.tex
% Version           : $Revision: 1.1 $
% Last-modified     : $Date: 2005/01/04 11:45:32 $
% Last-modifier     : FJ

\documentclass{splib}

\begin{document}
% main environment
\begin{protocol}%
% name
{BAN concrete Andrew Secure RPC}%
% authors
{Michael Burrows and Martin Abadi and Roger Needham}%
% date of the first publication
{1989}%
% editor name
{}%
% date of submission
{}%
% date of last change, empty or = date of submission
{14/11/2002}

\begin{abstract}
A concrete realization of the \crossref{andrew} protocol,
stronger and with less encryption.
Exchanged of a fresh shared key,
Symmetric key cryptography.
\end{abstract}

\begin{core}
\begin{declarations}
\dcl{A, B}{principal}
\dcl{Kab, K'ab}{symkey}
\dcl{Na, Nb, N'b}{nonce}
\dcl{succ}{nonce -> nonce}
\end{declarations}

\begin{messages}
\msg{1}{A}{B}{A, Na}
\msg{2}{B}{A}{\crypt{Na, K'ab}{Kab}}
\msg{3}{A}{B}{\crypt{Na}{K'ab}}
\msg{4}{B}{A}{Nb}
\end{messages}
\end{core}

\begin{explanation}
This protocol establishes the fresh
shared symmetric key \code{K'ab}.

The nonce \code{Nb} is sent in message \code{4}
to be used in a future session.


We assume that initially, the symmetric keys \code{Kab}
is known only to \code{A} and \code{B}.
\end{explanation}

\begin{property}
See \crossref{andrew}.
\end{property}

\begin{references}
\cite{BurrowsAbadiNeedham89}
\end{references}

\begin{attacks}
In \cite{Lowe96}, with 2 parallel runs
where the intruder \code{I} impersonates \code{B}.
\begin{messages}
\msg{i.1}{A}{I(B)}{A, Na}
\msg{ii.1}{I(B)}{A}{B, Na}
\msg{ii.2}{A}{I(B)}{\crypt{Na, K'ab}{Kab}}
\msg{i.2}{I(B)}{A}{\crypt{Na, K'ab}{Kab}}
\msg{i.3}{A}{I(B)}{\crypt{Na}{K'ab}}
\msg{ii.3}{I(B)}{A}{\crypt{Na}{K'ab}}
\msg{i.4}{I(B)}{A}{Ni}
\msg{ii.4}{A}{I(B)}{Nb}
\end{messages}
A fix to this attack can be found in \crossref{andrewLowe}.
\end{attacks}

\begin{see} %\crossref{}, see all.aux for labels names
\crossref{andrew},
\crossref{andrewBAN},
\crossref{andrewLowe}.
\end{see}

\end{protocol}
\end{document}

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