Protection of Hidden Volumes Against Damage 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 mounting an outer volume, type in its password and before clicking
OK, click
Mount Options :
In the
Mount Options dialog window, enable the option ‘
Protect hidden volume against damage caused by writing to outer volume ‘. In the ‘
Password to hidden volume ’ input field, type the
password for the hidden volume. Click
OK and, in the main password
entry dialog, click
OK .
Both passwords must be correct; otherwise, the outer volume will not be mounted. When hidden
volume protection is enabled, TrueCrypt does
not actually mount the hidden volume. It only
decrypts its header (in RAM) and retrieves information about the size of the hidden volume (from
the decrypted header). Then, the outer volume is mounted and any attempt to save data to the
area of the hidden volume will be rejected (until the outer volume is dismounted).
Note that TrueCrypt never modifies the filesystem (e.g., information about allocated clusters, amount of free space, etc.) within the outer volume in any way. As soon as the volume is dismounted, the protection is lost. When the volume is mounted again, it is not possible to determine whether the volume has used hidden volume protection or not. The hidden
