This post has been made after a google search. I found that thread from Arniekat:
http://www.linuxquestions.org/questions/showthread.php?p=3315974#post3315974The thread has been modified to suit the Debian distro.
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The Truecrypt binary needs to have root privileges. The fix is to create a group with the privilege of running the truecrypt binary and add your unprivileged (non-root) users to the truecrypt group so they can run Truecrypt.
Do the following (need to su):
# addgroup truecrypt
Now you edit the sudoers file (must be done with vi!)
# visudo
Add the following 2 lines to the bottom of the sudoers file:
# Allow users of truecrypt group to run truecrypt as root.
%truecrypt ALL=(root) NOPASSWD:/usr/bin/truecrypt
Save it and exit visudo
Now add your regular user (toto) to the truecrypt group
# adduser toto truecrypt
The Truecrypt file containers default mount on:
/media/truecryptX