True Crypt Container - Optimal Size?

Briefly,

1) I have installed TC on a USB thumb drive for use on several computers.

2) I wish to encrypt a 2 TB USB external hdd.

3) What is the optimal size for the "hidden container" within this encrypted 2 TB drive so as to have "plausible deniability"?

My fear is that if the accessible (not hidden) container appears too small, the existence of a hidden container would be obvious.

I assume that the hidden container must be of fixed size - and not expanding as more and more data is input.

Thanks!

Note: x942 did touch on this point and was very helpful, but unfortunately did not address my question as to optimal size for plausible deniability of the the hidden and non-hidden volumes:

 

I don't know if this is a good idea, so hopefully someone with more knowledge can point out any errors. I would leave the drive unpartitioned and unformatted so that post-encryption it looks like an unpartitioned, unformatted drive.

 

@0strodamus

TC requires partitioning. As for my 2 TB external USB drive, I intend for that to be dedicated to TC and TC only - no partitioning per se.

What I don't understand is what sizing each volume (the one where you are forced to give up a password) and the other "hidden" volume should ideally have.

I mean you could argue that if you made the "I give up; here's my password" partition only 10 GB and the Hidden Volume 1.99 TB (extreme example) it would look suspicious.

 

The optimal size is highly dependent on what you want to store on that hidden volume AND on what are you going to store on the "normal" (not hidden) volume. For instance, if you have 3 photos and a text and you keep them in the "normal" 2 TB volume, someone will surely suspect the existence of a hidden one!

However, I hope you are hiding from an adversary that can't resort to this: http://xkcd.com/538/

 

Multi-Terrabyte drives are almost as cheap as lattes these days. Not having them filled to capacity isn't that unusual...especially with multi-computer/tablet/phone households. You can't tell a hidden volume is there. If you don't protect it, and write to the outer volume, it will destroy the hidden. *Assume* is a lot different than *proven* where I live. I don't think you can even get a warrant with the first.

All that said, sure, if you can reasonably guess at your hidden volume data needs, buy a drive twice as big and fill it half way if it "looks" better. JMO.

PD

Just so I'm clear, when you mount the Outer "I give up" volume - it won't say 10GB...it'll be the full amount of the partition. They can only ask (your lawyer) why there is only 10 GB on a 2 TB drive. Only from within the Hidden volume, will it show the size of itself, which will be less than the total partition size. The Outer shows only the entire container/partition size...no matter how big or small the Hidden is.

Also (I just re-tested to make sure) 1. Checking the "Protect Hidden Volume" box, and then mounting the Outer volume *still* shows the total size - it doesn't show you the OV size only. 2. If an attacker said "Check that box" (to your lawyer?) go ahead and check it...what password are you going to put in there for something that doesn't exist? Ask him if you should put "allyourbasesarebelongtous" LOL.

 

PD is correct. Your size question is moot since the entire 2TB will be displayed during the mounting of the outer volume.

Additionally, be careful about using "outer volume protection" in a high threat model. If an adversary pulls up the TC control panel it will show "outer" instead of "normal". The outer flag means there is a hidden volume so you could not deny its existence.

Backup of the contents of the hidden volume and if you are forced to open the outer volume in "normal mode", just plan on the hidden volume being destroyed by an adversary. That is how it works.


OP,

What you might really be asking is how much data do I need to have on the outer volume to be realistic? There is no set answer. Any assumed answer simply cannot prove the existence of the hidden volume.

 

Yes, absolutely. The only way you can be burned with a Hidden volume, is if you get caught with the Outer volume open when the Hidden is protected. Never do that where other people are around. Never leave your computer unattended in that state. Think about cameras too, or telephoto lens' through a window

PD