I am using truecrypt to encrypt thumb drives and laptop harddrive etc, and have a question regarding the hidden volume option. As i understand it, an encrypted volume is created inside another, and the outer volume can be filled with "dummy" data. What i am wondering is, owdoes Truecrypt handle t hidden volume? would not the outer volume, if mounted, show up as almost full, even thou there is only a few files in the outer volume?
I think the official doc is pretty clear about that :
If you mount a TrueCrypt volume within which there is a hidden volume, you may read data stored on the (outer) volume without any risk. However, if you (or the operating system) need to save data to the outer volume, there is a risk that the hidden volume will get damaged (overwritten). To prevent this, you should protect the hidden volume in a way described in this section.
When you activate the Hidden Volume Protection:
As soon as a write operation to the hidden volume area is denied/prevented (to protect the hidden volume), the entire host volume (both the outer and the hidden volume) becomes write-protected until dismounted (the TrueCrypt driver reports the 'invalid parameter' error to the system upon each attempt to write data to the volume).
The outer volume is not aware of the hidden volume, and that's why the hidden part risk to be corrupted (overwritten). So, you won't see the usage of the hidden volume in the outer's usage.