I would like to use encryption on my external HDD but I would like to be able to access the encrypted data from Windows as well. As suggested in other questions, TrueCrypt is one option here, or I am using momentarily encfs, which is not available for Windows.

But my question goes further: I would like to be able to access the encrypted partition from Windows without installation as I will be using it from different Windows machines for which I have no administrator access. My main OS is Linux and I have full root access to that computer.

Is there a full disk or file based encryption which I can use cross platform and which does not require installation under Windows?

ADDITION:

It seems that TrueCrypt provides a portable mode which fulfills my requirements partly: http://www.truecrypt.org/docs/?s=truecrypt-portable, but still the TrueCrypt driver needs to be installed by an administrator... pitty

Thanks