GBDE-GEOM Based Disk Encryption on FreeBSD

BSD Forums writes "The ever increasing mobility of computers has made protection of data on digital storage media an important requirement in a number of applications and situations. GBDE is a strong cryptographic facility for denying unauthorised access to data stored on a 'cold' disk for decades and longer. GBDE operates on the disk(-partition) level allowing any type of file system or database to be protected. A significant focus has been put on the practical aspects in order to make it possible to deploy GBDE in the real world. FreeBSD's Poul-Henning Kamp says in an email to freebsd-current that he has uploaded this paper and slides which he presented at BSDcon 2003, California, USA."

Comments

CD-ROM encryption

[avleeuwen]

One of the cooler features that come with GBDE is the fact that you can encrypt CD-ROM images. This makes for a very secure way of getting someone a lot of sensitive data. A patch was recently posted on the current@ mailing list to allow this.

That is very interesting

[kasperd]

I have been working on article on disk encryption though it is not quite ready to be published yet. I didn't know anybody else was working seriously on this. I know about cryptoloop in Linux. It is bad, but not the worst I have seen described. It is nice to finally see somebody but me realizing that disk encryption is not as simple as those implementing it think. I don't know how the more "professional" products work. What I have realized is, that good disk encryption has an overhead on disk usage. Those "professional" products I have seen just a few details about doesn't have for too litle overhead for good crypto. The system described by the article only protects cold disks, no protection at all for hot disks. What I describe in my own article actually has some protection for hot disks, not much protection though, because the hot disk naturally limits the protection that is possible.

Random comments...

[ssimpson]

(Full disclosure: I've been involved with the Win32 Scramdisk project in the past)

Hhhm, this is pretty interesting. I am not aware of any other disk encryption program (Scramdisk, DriveCrypt, LoopAES, PGPDisk, BestCrypt etc) that offers sector remapping. It's useful because it prevents standard disk structures from being exploited in a known plaintext attack (note: with current knowledge, this is only a theoretical weakness with AES anyway).

Apart from that it looks a pretty standard On-The-Fly-Encryption (OTFE) system. It does appear to be slightly more complex than most programs, but this is offset by the peer review from (at least...) two very well respected cryptographers - Dr David Wagner and Lucky Green. I am not aware of any of the other OTFE systems being reviewed by anyone half this competent.

Last paragraph of 6 says "RSA2/512" should read SHA2/512.

I'd personally be worried about the use of a static (zero!) IV. I know the key is random, but.....Oh well, if Dr Wagner has peer reviewed it then this can't be much of an issue.

From the paper: "A truly paranoid setup would leave the computer con- figured to boot the Windows system by default, and locate the GBDE data in such a way that it would be destroyed by the act of doing so."

It's likely this wouldn't work - the first thing a half-competent adversary would do is image all disks in a system before booting....It's forensic 101.