<chapter id="chiasmus">

<chapterinfo>
<authorgroup>
<author>
<firstname>Jan-Oliver</firstname>
<surname>Wagner</surname>
<affiliation><address>
<email>jan@intevation.de</email>
</address></affiliation>
</author>
<author>
<firstname>Till</firstname>
<surname>Adam</surname>
<affiliation><address>
<email>till@kdab.net</email>
</address></affiliation>
</author>

</authorgroup>

<date>2005-06-30</date>
<releaseinfo>1.8</releaseinfo>
</chapterinfo>

<title>Using the Chiasmus encryption tool</title>

<sect1 id="chiasmus-preparations">
<title>Preparations</title>

<para>
To encrypt and decrypt with Chiasmus, you need the BSI's Chiasmus 
command line tool for GNU/Linux. It is intended solely for use in
government agencies and availabe from the BSI on request.
</para>

<para>
When executed without parameters, the <command>chiasmus</command>
program should output something like:
</para>

<para>
<screen>
Chiasmus (R) fuer Windows K 1.8.0.0
Bundesamt fuer Sicherheit in der Informationstechnik
Kontakt: Chiasmus@bsi.bund.de
(C) 2001 - 2005
[ ...]
</screen>
</para>

<para>
Version 1.8.0.0 was tested succesfully. Other versions may or may not
work correctly.
</para>

<para>
As a last preparation step a directory which will hold the key files
ending in <filename>.xis</filename> has to be created, if none already exists. Usually
<filename class="directory">~/.chiasmus/</filename>  is used.
</para>

</sect1>

<sect1 id="chiasmus-configuration">
	<title>Configuration</title>
<para>
Select <menuchoice><guimenu>Settings</guimenu><guimenuitem>Configure KMail
</guimenuitem></menuchoice> and choose the <guilabel>Crypto-Backends</guilabel>
tab on the Security page. Select the entry for <guilabel>Chiasmus</guilabel> and click 
<guibutton>Configure....</guibutton> to open the configuration dialog 
for the Chiasmus backend.
</para>

<para>
Specify the path to the Chiasmus binary and the directory where key files are
to be stored, using the file selection dialogs which open when you click the
folder icons next to the path entries.
</para>

<para>
Close the backend configuration dialog by clicking <guibutton>Ok</guibutton>
and check the <guilabel>Chiasmus Checkbox</guilabel> to activate it. Then also close the main 
configuration dialog.
</para>

</sect1>


<sect1 id="chiasmus-encryption">
	<title>Encryption</title>
<para>
To encrypt a message with Chiasmus, select <menuchoice><guimenu>
Options</guimenu><guimenuitem>Encrypt message with chiasmus
</guimenuitem></menuchoice>. A dialog comes up in which you can select
the key file to use, as well as additional command line arguments to
be passed to <command>chiasmus</command>.
</para>

<note>
<para>
If you want to use Chiasmus encryption regularly, you should add
an icon for that option to your toolbar, using <menuchoice><guimenu>
Settings</guimenu><guimenuitem>Configure toolbars</guimenuitem>
</menuchoice>. Move the entry for <guilabel>Encrypt with Chiasmus
</guilabel> from the left side of the dialog to the right, using the
buttons between the two panes. You can then quickly enable or disable
Chiasmus encryption using that toolbar button and have a visual 
indication of the current state.
</para>
</note>

<note>
<para>
If automatic saving of backup copies of currently edited messages is
enabled, you will be prompted for your Chiasmus password, if Chiamsus
encryption is active.
</para>
</note>

<para>
On message sending, you will be prompted for the password. If the password
is correct, the text of the message and all its attachments will be
encrypted.
</para>

<note>
<para>
The other signing and encryption options are completely independent of
the Chiasmus encryption. You can use those in addition to Chiasmus,
&eg; to sign the message.  Additional encryption, on the other hand,
does not make much sense and complicates decryption for the
recipients.
</para>
</note>

</sect1>

<sect1 id="chiasmus-decryption">
	<title>Decryption</title>
<para>
&kmail; and &kontact; detect messages that have been encrypted
using Chiasmus and will automatically ask for the key file to use for
decryption, as well as the corresponding password. If the password is correct, the
message will be decrypted and displayed.
</para>

<para>
To decrypt attachments that were encrypted using Chiasmus (&ie; those which have
a file name ending in <filename>.xia</filename>), right-click on the 
attachment you want to decrypt and select <menuchoice><guimenuitem>Decrypt using Chiasmus
</guimenuitem></menuchoice>. After you have chosen a key file to be used for decryption and
entered the correct password for it, a file selection dialog will allow you
to specify where the decrypted attachment should be saved.
</para>
</sect1>

</chapter>
