apt sources.list:

<pre>
cat &gt;/etc/apt/sources.list.d/rus-cert.list &lt;&lt;EOF
deb https://deb.cert.uni-stuttgart.de/debian stable main
EOF
</pre>

and trust our <a href="https://deb.cert.uni-stuttgart.de/Release.key">Release.key</a>:

<pre>
wget -O/etc/apt/trusted.gpg.d/cert.gpg https://deb.cert.uni-stuttgart.de/cert.gpg
</pre>