%%% -*-latex-*-
%%%
-%%% $Id: storin.tex,v 1.1 2000/05/21 11:28:30 mdw Exp $
+%%% $Id: storin.tex,v 1.2 2000/05/21 21:43:26 mdw Exp $
%%%
%%% Definition of the cipher
%%%
%%%----- Revision history ---------------------------------------------------
%%%
%%% $Log: storin.tex,v $
+%%% Revision 1.2 2000/05/21 21:43:26 mdw
+%%% Fix a couple of typos.
+%%%
%%% Revision 1.1 2000/05/21 11:28:30 mdw
%%% Initial check-in.
%%%
\ar `r "d"+(0, 0.5); p+(1, 0) "x" \ar "x"; "d"%
}
-\def\figstart{%
+\def\figstart#1{%
\POS 0;<1cm,0cm>:%
\turnradius{4pt}%
- \ar @{-} (0, 0) *+{a}; p-(0, 0.5) ="a"
- \ar @{-} (2, 0) *+{b}; p-(0, 0.5) ="b"
- \ar @{-} (4, 0) *+{c}; p-(0, 0.5) ="c"
- \ar @{-} (6, 0) *+{d}; p-(0, 0.5) ="d"
+ \ar @{-} (0, 0) *+{a#1}; p-(0, 0.5) ="a"
+ \ar @{-} (2, 0) *+{b#1}; p-(0, 0.5) ="b"
+ \ar @{-} (4, 0) *+{c#1}; p-(0, 0.5) ="c"
+ \ar @{-} (6, 0) *+{d#1}; p-(0, 0.5) ="d"
}
\def\figround#1#2#3#4#5{%
\ar @{--} "d"; "d"-(0, 2) ="d"
}
-\def\figwhite#1#2#3#4{%
+\def\figwhite#1#2#3#4#5{%
\ar @{.} "a"-(0.5, 0); p+(8, 0)
\POS "a"+(8, -1)*[r]\txt{Postwhitening}
\figkeymix{#1}{#2}{#3}{#4}
- \ar "a"; p-(0, 1) *+{a'}
- \ar "b"; p-(0, 1) *+{c'}
- \ar "c"; p-(0, 1) *+{b'}
- \ar "d"; p-(0, 1) *+{d'}
+ \ar "a"; p-(0, 1) *+{a#5}
+ \ar "b"; p-(0, 1) *+{b#5}
+ \ar "c"; p-(0, 1) *+{c#5}
+ \ar "d"; p-(0, 1) *+{d#5}
}
\begin{document}
\leavevmode
\begin{xy}
\xycompile{
- \figstart
+ \figstart{}
\figround{0}{1}{2}{3}{Round 1}
\figround{4}{5}{6}{7}{Round 2}
\figgap
- \figwhite{32}{33}{34}{35}}
+ \figwhite{32}{33}{34}{35}{'}}
\end{xy}
\caption{The Storin encryption function}
\label{fig:cipher}
\leavevmode
\begin{xy}
\xycompile{
- \figstart
+ \figstart{'}
\figiround{32}{33}{34}{35}{Round 1}
\figiround{28}{29}{30}{31}{Round 2}
\figgap
- \figwhite{0}{1}{2}{3}}
+ \figwhite{0}{1}{2}{3}{}}
\end{xy}
\caption{The Storin decryption function}
\label{fig:decipher}
The initial objective was to produce a cipher which played to the particular
strengths of digital signal processors. DSPs tend to have good multipliers,
-and are particularly good at matrix multiplication. The decision use a
+and are particularly good at matrix multiplication. The decision to use a
matrix multiplication over $\mathbb{Z}_{2^{24}}$ seemed natural, given that
24 bits is a commonly offered word size.