[Tex/LaTex] How to draw protocol interaction using tikzpicture

math-modetikz-pgf

I have a question on using the tikzpicture package.

I have a protocol interaction on which two participants want to exchange some numbers, say α and β. I need bilateral arrows, and on top of it would be α and below it the β. That means these two participants are exchanging the numbers simultaneously. BTW, I don't need dots in the side of arrows, but some calculations which results in α or β must be placed there.

alt text

How can I have this output? I don't know if I have chosen the right package but it seems to me that this is the right choice.
Every sample that I have seen so far uses some dots and creates a matrix, but I don't know how to replace dots with these terms. BTW, I have no idea how can I have that arrow and even making it larger.
Any good tutorial with examples close to my need will be appreciated.

Best Answer

You don't need TikZ for this. If you're using LaTeX, you just need amsmath and the mathtools package (both of which you likely have):

\documentclass{minimal}
\usepackage{amsmath}
\usepackage{mathtools}

\begin{document}
  \[\begin{matrix}
      x \xleftarrow{\quad R\quad} \mathcal{Z}_q            &\quad
      \xrightleftharpoons[\beta=g^y]{\quad\alpha=g^x\quad} \quad&
      y \xleftarrow{\quad R\quad} \mathcal{Z}_q            \\
      g^{xy} & & g^{xy} \\
  \end{matrix}\]
\end{document}

This produces the following output:

Extensible arrows and harpoons.

The amsmath package provides the \xleftarrow and \xrigharrow commands, which set an eXtensible \leftarrow and \righarrow, respectively; their mandatory argument is set on top, and their optional argument is set below (\xleftarrow[below]{above}). Normally, it's just as wide as necessary for the text, so I inserted \quads around the text to space it out. The mathtools package, which extends amsmath, provides more extensible arrows, including \xleftrightarrow (for an extensible ↔), \xLeftrightarrow (for an extensible ⇔), \xleftrighharpoons (for an extensible ⇋; the upside-down version of the symbol in the example picture), and \xrightleftharpoons (for an extensible ⇌, as seen in the example picture), any of which could be used here depending on your tastes.

Also, note that you shouldn't need to space out the \xrightleftharpoons like I did (which is why there's &\quad ... \quad&), but apparently I needed to here (though in LaTeXit I didn't, so with some small change you probably wouldn't need to). You only need the matrix here since you want to align the g^{xy}s with the first and third arrows; if you just wanted the top line, you wouldn't need to bother.

Related Solutions

[Tex/LaTex] Legend in tikzpicture

Here is a solution based on Using a pgfplots-style legend in a plain-old tikzpicture. There are two examples: in the first one, the descriptions in the legend are centered, while in the second one, the descriptions are left aligned.

To define numbers in the legend, I added a key number in legend:

% definition to insert numbers
\pgfkeys{/pgfplots/number in legend/.style={%
        /pgfplots/legend image code/.code={%
            \node at (0.295,0){#1};
        },%
    },
}

Centered descriptions

The example:

\documentclass[a4paper,11pt]{article}
\usepackage{tikz}
\usetikzlibrary{calc,shadings}

\usepackage{pgfplots}

% Code from Christian Feuersänger
% https://tex.stackexchange.com/questions/54794/using-a-pgfplots-style-legend-in-a-plain-old-tikzpicture#54834

% argument #1: any options
\newenvironment{customlegend}[1][]{%
    \begingroup
    % inits/clears the lists (which might be populated from previous
    % axes):
    \csname pgfplots@init@cleared@structures\endcsname
    \pgfplotsset{#1}%
}{%
    % draws the legend:
    \csname pgfplots@createlegend\endcsname
    \endgroup
}%

% makes \addlegendimage available (typically only available within an
% axis environment):
\def\addlegendimage{\csname pgfplots@addlegendimage\endcsname}

%%--------------------------------

% definition to insert numbers
\pgfkeys{/pgfplots/number in legend/.style={%
        /pgfplots/legend image code/.code={%
            \node at (0.295,-0.0225){#1};
        },%
    },
}

\begin{document}
\begin{tikzpicture}
\draw (0,0)--(10,0);
\draw(0,-0.2)--(0,0.2)node[above,red]{\small{0}};
\draw(10,-0.2)--(10,0.2)node[above,blue]{\small{1}};
%------------------%
\foreach \m[count=\mi] in {0.909090909,...,9.090909090}
\draw(\m,-0.1)--(\m,0.1) node[anchor=north](a\mi){};
\draw[dotted]($(a2)+(0,0.1)$)--($(a2)+(0,0.4)$);
\draw[dotted]($(a3)+(0,0.1)$)--($(a3)+(0,0.4)$);
\draw[stealth-stealth,red,opacity=0.4]($(a3)+(0,0.4)$)--($(a2)+(0,0.4)$)node[anchor=south west,xshift=0.23cm,black,opacity=1]{\small{$R$}};
%------------------%
\foreach \x/\xtext in {0.7/$u_1$,1.2/$u_2$,4.5/$u_3$,5.2/$u_4$,5.6/$u_5$,7.5/$u_6$}
\shade[ball color=blue]  (\x,0 ) circle (0.1cm) node[below=0.1cm]{\small{\xtext}};
%------------------%
% inf user
\shade[ball color=green]  (0,0 ) circle (0.1cm) node[below=0.1cm]{\small{$u_{inf}$}};

\begin{customlegend}[
legend entries={ % <= in the following there are the entries
$R$: infection radius,
$u_i$: users,
$u_{inf}$: initial infected user, 
social space max dimension,
social space min dimension,
example of rectangle
},
legend style={at={(4.5,3.5)},font=\footnotesize}] % <= to define position and font legend
% the following are the "images" and numbers in the legend
    \addlegendimage{stealth-stealth,red,opacity=0.4}
    \addlegendimage{mark=ball,draw=white}
    \addlegendimage{mark=ball,ball color=green,draw=white}
    \addlegendimage{number in legend=1,blue}
    \addlegendimage{number in legend=0,red}
    \addlegendimage{area legend,orange,fill=orange!20}
\end{customlegend}
\end{tikzpicture}

\end{document}

which gives:

enter image description here

Left aligned descriptions

The code is:

\documentclass[a4paper,11pt]{article}
\usepackage{tikz}
\usetikzlibrary{calc,shadings}

\usepackage{pgfplots}

% Code from Christian Feuersänger
% https://tex.stackexchange.com/questions/54794/using-a-pgfplots-style-legend-in-a-plain-old-tikzpicture#54834

% argument #1: any options
\newenvironment{customlegend}[1][]{%
    \begingroup
    % inits/clears the lists (which might be populated from previous
    % axes):
    \csname pgfplots@init@cleared@structures\endcsname
    \pgfplotsset{#1}%
}{%
    % draws the legend:
    \csname pgfplots@createlegend\endcsname
    \endgroup
}%

% makes \addlegendimage available (typically only available within an
% axis environment):
\def\addlegendimage{\csname pgfplots@addlegendimage\endcsname}

%%--------------------------------

% definition to insert numbers
\pgfkeys{/pgfplots/number in legend/.style={%
        /pgfplots/legend image code/.code={%
            \node at (0.125,-0.0225){#1}; % <= changed x value
        },%
    },
}
\pgfplotsset{
every legend to name picture/.style={west}
}

\begin{document}
\begin{tikzpicture}
\draw (0,0)--(10,0);
\draw(0,-0.2)--(0,0.2)node[above,red]{\small{0}};
\draw(10,-0.2)--(10,0.2)node[above,blue]{\small{1}};
%------------------%
\foreach \m[count=\mi] in {0.909090909,...,9.090909090}
\draw(\m,-0.1)--(\m,0.1) node[anchor=north](a\mi){};
\draw[dotted]($(a2)+(0,0.1)$)--($(a2)+(0,0.4)$);
\draw[dotted]($(a3)+(0,0.1)$)--($(a3)+(0,0.4)$);
\draw[stealth-stealth,red,opacity=0.4]($(a3)+(0,0.4)$)--($(a2)+(0,0.4)$)node[anchor=south west,xshift=0.23cm,black,opacity=1]{\small{$R$}};
%------------------%
\foreach \x/\xtext in {0.7/$u_1$,1.2/$u_2$,4.5/$u_3$,5.2/$u_4$,5.6/$u_5$,7.5/$u_6$}
\shade[ball color=blue]  (\x,0 ) circle (0.1cm) node[below=0.1cm]{\small{\xtext}};
%------------------%
% inf user
\shade[ball color=green]  (0,0 ) circle (0.1cm) node[below=0.1cm]{\small{$u_{inf}$}};

\begin{customlegend}[legend cell align=left, %<= to align cells
legend entries={ % <= in the following there are the entries
$R$: infection radius,
$u_i$: users,
$u_{inf}$: initial infected user, 
social space max dimension,
social space min dimension,
example of rectangle
},
legend style={at={(4.5,3.5)},font=\footnotesize}] % <= to define position and font legend
% the following are the "images" and numbers in the legend
    \addlegendimage{stealth-stealth,red,opacity=0.4}
    \addlegendimage{mark=ball,draw=white}
    \addlegendimage{mark=ball,ball color=green,draw=white}
    \addlegendimage{number in legend=1,blue}
    \addlegendimage{number in legend=0,red}
    \addlegendimage{area legend,orange,fill=orange!20}
\end{customlegend}
\end{tikzpicture}

\end{document}

Result:

enter image description here

[Tex/LaTex] Using node shapes or self made tikzpicture as image in legend

You can set the code that's used to draw the legend image using legend image code/.code={ ...}:

\documentclass[a4paper,11pt]{article}
\usepackage{tikz}
\usetikzlibrary{shapes.geometric}

\usepackage{pgfplots}

% Code from Christian Feuersänger
% http://tex.stackexchange.com/questions/54794/using-a-pgfplots-style-legend-in-a-plain-old-tikzpicture#54834

% argument #1: any options
\newenvironment{customlegend}[1][]{%
    \begingroup
    % inits/clears the lists (which might be populated from previous
    % axes):
    \csname pgfplots@init@cleared@structures\endcsname
    \pgfplotsset{#1}%
}{%
    % draws the legend:
    \csname pgfplots@createlegend\endcsname
    \endgroup
}%

% makes \addlegendimage available (typically only available within an
% axis environment):
\def\addlegendimage{\csname pgfplots@addlegendimage\endcsname}

%%--------------------------------

% definition to insert numbers
\pgfkeys{/pgfplots/number in legend/.style={%
        /pgfplots/legend image code/.code={%
            \node at (0.295,-0.0225){#1};
        },%
    },
}

\begin{document}
\begin{tikzpicture}

% node shaped as cylinder
\node[shape=cylinder](c) at (0,0){};

% cylinder drawn myself
\draw(3,3)--(4,3);
\draw(3,4)--(4,4);
\draw(3,4) arc [x radius=0.1, y radius=0.5, start angle=90, end angle=270];
\draw(4,3.5) ellipse (0.1 and 0.5);

\begin{customlegend}[legend cell align=left,
legend entries={ cylinder},
legend style={at={(6,3)},font=\footnotesize}]
\addlegendimage{legend image code/.code={\node [draw, cylinder, minimum size=1em] {};}}
\end{customlegend}

\end{tikzpicture}


\end{document}

Best Answer

Related Solutions

[Tex/LaTex] Legend in tikzpicture

[Tex/LaTex] Using node shapes or self made tikzpicture as image in legend

Related Question