I need to go through airport security and customs, and its known that at least the German customs (http://en.wiktionary.org/wiki/Bundestrojaner) (and I suspect others as well) try to upload software to the system.
So here my question:
How can I make sure that nobody tempers with my system while I do not have physical access to it (they usually take it backdoors to "inspect" it), or verify it has been accessed / changed?
I have installed a BIOS password, but in a hard case they could just unplug my harddrive, and do something directly. The other option I thought of was doing a MD5 sum over my complete HDD, but as soon as I reboot, that sum will change most likely.
How can I either avoid to have a system, to which I might lose physical governance over temporarily, have a Trojan / Virus / something installed, or otherwise notice an intrusion?