* Double-check the key fingerprint: <pre>
\# apt-key fingerprint
- pub 1024D/9DDD734B 2011-02-05
- Key fingerprint = 9606 1022 48CB D253 4A12 5DE3 9777 CA77 9DDD 734B
- uid Wilhelm-Gymnasium, Braunschweig (Repository Key)
- sub 2048g/DF8AB114 2011-02-05
+ pub 2048R/0D05ED3E 2014-01-01 [expires: 2017-12-31]
+ Key fingerprint = 50ED 1BAD E0A5 910A 8B26 84B3 0B02 3D2B 0D05 ED3E
+ uid Wilhelm-Gymnasium Braunschweig (Repository Key) <packages@wilhelm-gym.net>
+ sub 2048R/1CCA0A2B 2014-01-01 [expires: 2017-12-31]
</pre>