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As I understand it plausible deniability gives the user the option of having two passwords, one you provide the authorities/extortionist with and another that you might use for your self and files you may not want them seeing.

If someone were to use the plausible deniability and a court forced them to reveal their password in addition to the history file, are there any other files you might want to shred so as that there was not a record of using the "good" password?

As I see it you're as good as your weakest link, if theres a record of commands you've typed into your server isn't this all somewhat pointless?

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migrated from serverfault.com Aug 24 '12 at 23:54

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My point about the history file is not that I'm saving passwords there but that they are being saved there by default. Are there any other files that need to be shredded? –  Andrew Aug 24 '12 at 22:27
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I am confused. Why would the password appear in the history file? Also, if you are concerned about the history file, disable it. (Or rephrase your question: "How do I disable shell command history?" As written, you aren't really asking a question but starting a discussion (which doesn't really fit the Q&A format.) –  Aaron Copley Aug 24 '12 at 22:35
    
The password appears in the history because I use the command line to mount it. For example. If I type history | grep truecrypt I get 979 truecrypt -t /mnt/ITSTUDY -p mypassword /mnt/Data/ Yes I can disable the history file but is there a record of my typing stored in any other files? –  Andrew Aug 24 '12 at 22:55
    
Basically, you are curious where your activity in the terminal might be logged to, right? If so, you may want to edit the question and re-phrase it to be more generally about the security of typing passwords in a terminal. –  B-Con Aug 24 '12 at 23:58

3 Answers 3

As an alternative (or in addition) to completely disabling your command history, you could mount your encrypted volumes interactively. I haven't tried this myself, but the manpage tells us the -i option requests all security-sensitive information interactively from the user (so it doesn't get logged in your history file).

Of course as already indicated by others, if an "attacker" were to install a keylogger or such onto your system, none of these methods will work.

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Why would you be saving your Truecrypt passwords in a file in the first place?

You've asked some questions we can't answer, such as what courts might require and how to respond to them.

As always with security, you need to be aware of what your threats are. If in your threat model, a government is one of the threats, then you need to do a lot more than just encrypt your hard drive.

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Absolutely. I encrypt my drives, just in case, but the true security is 10 ounces of thermite on top of the drives, and a small chemical flare (like a road flare) set to ignite if there's a sudden power loss, such as would happen if the authorities tried to seize my box. Much better security than just encryption and plausible deniability. Does make kind of an expensive mess during power outages, though... and a bit of a fire hazard too. But at least I don't have to worry about stumbling around in the dark when the power dies. –  HopelessN00b Aug 24 '12 at 23:16
    
    
Nah, the molten metal dripping off the hard drives make short work of the RAM. And the motherboard. And the case... the carpet too... like I said, it creates an expensive mess. –  HopelessN00b Aug 24 '12 at 23:21
    
Did you read our blog post on exactly this subject: security.blogoverflow.com/2012/02/… –  Rory Alsop Aug 25 '12 at 22:09
    
They won't necessarily be turning it off: wiebetech.com/products/HotPlug.php so you may want to include a radio or GPS based trigger as well. –  Grant Aug 27 '12 at 14:12

To stop your command line history from being recorded check out:

http://www.commandlinefu.com/commands/view/1512/execute-a-command-without-saving-it-in-the-history

Of course, there could also be a key logger on your system or externally, if you are in a country where the courts can force you to give up your password, they might be allowed to come into your home and install one, or even do evil maid attack:

http://www.schneier.com/blog/archives/2009/10/evil_maid_attac.html

You have to decide what is the reasonable level of protection for data and a system. You could also setup a system to disable or trash logging, or fill your logs with bogus entries.

You might also want to look into using a key in addition to the password. Keep the key off the system, destroy the key to preserve your data.

If its acceptable that you can tell the court the key was destroyed, then your done. If its some regime or group that doesn't care (e.g., will torture or imprison you) then its a moot point. A better solution would be to setup a remote system in a safe country and use some number of TOR and VPN tunnels and a remote session so that nothing is stored locally or retained, clear your history of connecting to the remote system or use a live cd to connect.

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