Commentary

George Hulme
 

TrueCrypt: No Cloaking Crypto For You

Researchers say the steganography feature, also known as the Deniable File System (DFS), in TrueCrypt may not provide the "security by obscurity" users hoped for.

Researchers say the steganography feature, also known as the Deniable File System (DFS), in TrueCrypt may not provide the "security by obscurity" users hoped for.Over at our sister site, Dark Reading, senior editor Kelly Jackson Higgins covered some interesting research conducted by researchers at the University of Washington and British Telecommunications' Bruce Schneier that cracked the DFS feature. In a nutshell, the DFS feature aims to both encrypt files and then hide them in an "invisible" section of the hard drive so that snoops wouldn't know of their existence at all.

It seems certain -- extremely common -- file types, such as Microsoft Vista, Word, and Google Desktop reveal the DFS partition.


More Security Insights

White Papers

More >>

Reports

More >>

Webcasts

More >>

From Jackson's story:

The researchers were able to get around DFS in versions 5.0 and below of TrueCrypt's encryption-on-the-fly tool, and will present their findings on the hack at the Usenix HotSec '08 summit next week in San Jose, Calif.

However, the developers of the open source TrueCrypt say the latest version isn't vulnerable, but highly regarded cryptographer Schneier ain't buying that claim, and contends DFS is easier to hack than encryption:

TrueCrypt's developers, meanwhile, say the just-released new version of the software, 6.0, remedies the leakage problem with DFS. "To our best knowledge, TrueCrypt 6 solves all the issues," says David, one of TrueCrypt's developers. The new features include the ability to create and run a hidden encrypted operating system, for example.

Schneier, however, isn't convinced that TrueCrypt 6 can't be hacked. The version had not yet been released when he and the UW researchers did their work, but Schneier thinks the outcome would likely be basically the same. "The new version will definitely close some of the leakages, but it's unlikely that it closed all of them," he says. Schneier, who has studied the viability of the so-called "deniable" file system model in the past, says DFS is actually easier to hack than encryption, and that there may be no way to make files truly undetectable on a drive. "Deniability is a much harder security feature to enable than secrecy," he says. (See Schneier On Schneier and Schneier: In Touch With Security's Sensitive Side.)

Now, proving that a file exists does, in fact, break DFS -- but that's not the same as recovering the encrypted file. The researchers say that only some of the file's contents can be recovered when encrypted in DFS.

My takeway: ignore the DFS feature and use TrueCrypt's full disk encryption. That's always been safer than only encrypting files and folders.

The full paper is available here.


Related Reading




Currently we allow the following HTML tags in comments:

Single tags

These tags can be used alone and don't need an ending tag.

<br> Defines a single line break

<hr> Defines a horizontal line

Matching tags

These require an ending tag - e.g. <i>italic text</i>

<a> Defines an anchor

<b> Defines bold text

<big> Defines big text

<blockquote> Defines a long quotation

<caption> Defines a table caption

<cite> Defines a citation

<code> Defines computer code text

<em> Defines emphasized text

<fieldset> Defines a border around elements in a form

<h1> This is heading 1

<h2> This is heading 2

<h3> This is heading 3

<h4> This is heading 4

<h5> This is heading 5

<h6> This is heading 6

<i> Defines italic text

<p> Defines a paragraph

<pre> Defines preformatted text

<q> Defines a short quotation

<samp> Defines sample computer code text

<small> Defines small text

<span> Defines a section in a document

<s> Defines strikethrough text

<strike> Defines strikethrough text

<strong> Defines strong text

<sub> Defines subscripted text

<sup> Defines superscripted text

<u> Defines underlined text

InformationWeek encourages readers to engage in spirited, healthy debate, including taking us to task. However, InformationWeek moderates all comments posted to our site, and reserves the right to modify or remove any content that it determines to be derogatory, offensive, inflammatory, vulgar, irrelevant/off-topic, racist or obvious marketing/SPAM. InformationWeek further reserves the right to disable the profile of any commenter participating in said activities.

Disqus Tips To upload an avatar photo, first complete your Disqus profile. | View the list of supported HTML tags you can use to style comments. | Please read our commenting policy.
T-Shirt Giveaway T-Shirt Giveaway: Each week we're selecting one great comment from our readers. The author of the comment will receive an InformaitonWeek Community t-shirt. So get posting!
Subscribe to RSS

Resource Links