[unisog] OT: Putting Encyption Functions in the HDDs

Cosmin Stejerean cstejerean at gmail.com
Wed Apr 26 05:11:03 GMT 2006


The fact that the drive uses 3DES doesn't make me feel safe because
saying that something uses 3DES is incredibly vague. There are many
ways to use 3DES, and each is fit for certain situations. My guess is
that it is using ECB mode since CBC would require
encrypting/decrypting the entire drive to do reads / writes. If this
is using ECB mode then some interesting attacks could be mounted
against it.

Aside of implementation details (which sometimes prove to be the weak
spot) the biggest problem with encryption is the KEY. The data is only
as safe as the key.

Also, the article mentions that there are 4 user passwords and 4
master passwords. This is great, but since all the passwords have
access to the drive it means that the key is not derived from the
password but rather stored somewhere on the drive. I would hope there
are multiple copies each encrypted with a key that is derived from one
of the passwords with access to the drive. The key could also be
stored in plaintext but protected from tampering using hardware
protection (much like your USB tokens). How this key is generated
plays a big factor on determining how long for an attacker to decrypt
the data.

The last concern I have with this comes back to using passwords. I see
mentions of potentially integrating this with stronger authentication
mechanisms but as long as it is using passwords it has some potential
flaws. I wonder about the limitation on password size (8 chars would
be pretty bad). Also I am not sure if they have any way of enforcing
users to pick strong passwords. A password of 'password' would not
keep your data very safe. Doing a dictionary attack followed by an
exhaustive search of the password space will require much less than
cracking 3DES by bruteforce. I would bet than an attacker than got his
hands on a laptop which contains credit card info is willing to wait 6
months to crack the encryption since most of the cards will be valid
at the end of the 6 month period and if the data contains social
security numbers and other personal info the data is valuable for many
years to come so being willing to wait a couple of years to crack the
encryption is not out of the question.

What I am worried about is that crypto magic dust will once again be
sprinkled on top of a problem without actually solving the entire
problem but rather create a false sense of security. If this solution
fails to adequately protect the content of a hard drive the only
result of this is will be that companies won't be required to disclose
when a laptop was stolen because they can assume the data is safe.

--
Cosmin Stejerean

On 4/25/06, Saqib Ali <docbook.xml at gmail.com> wrote:
> I found this article which better explains the enccryption process in
> FDE drives. Essentially it uses 3DES with EDE
> (encryption-decryption-encryption) mode with 3 64-bit keys.
>
> See:
> http://www.dailytech.com/article.aspx?newsid=1493
>
> --
> Saqib Ali, CISSP, ISSAP
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