From: Glenn_Everhart at bankone.com (Glenn_Everhart@...kone.com)
Subject: harddisk encryption

Comments on hard drive encryptors:

1. If the encryptor encrypts your boot disk, it has to be involved early in the
boot process and may be broken by anything that changes the system boot sequence.
On the whole such a product would likely need two different drivers, one of which
would change BIOS behavior, and the other of which would change runtime
OS behavior, and they must be in synch with one another.

  This is fine until you decide to change operating systems, at which point the boot
may change and make your old data suddenly disappear. Things on the other hand are
easier if the encrypting disk product only encrypts data devices (including virtual
disks) since only one driver need be used.

2. In the event of disk crash or emergency, unless a tool is provided to allow you
to access the encrypted disk from somewhere else, anything which causes an OS to
become non bootable may be unfixable. You would not normally want such a tool online,
but when you need it, you REALLY need it.

3. If a product says it can encrypt local disks but not network ones, you may want
to know what exactly is going on. Something that exists just above the hardware control
layer would be expected to produce disk structures which would share across networks
normally when the encryption keys had been entered. If some OS layers cannot see
the disk as a normal disk, some programs may also be affected.

4. An interesting question to ask of such a package is whether the data in any
disk block is a cipher depending only on a fixed key and the original data. If so,
and the same key is used for every block, there are attacks which can be used
to compromise such a system without having to decrypt it all. If on the other hand
something else is an input, you need to know what else is used and how it is
used and how key scheduling is done, to make any estimate of how strong the
cipher really is.

(Now mind: most of the attackers will not be cryptanalysts, and thus even a
cipher that cryptanalysts laugh at has value in discouraging curious system
admins, PHBs, or others who may be able to get privileged access to a box but
lack knowledge or time to crack the cipher. A vendor or author who acknowledges
this is not vending snake oil...just admitting limitations of some methods.)

The Ultimaco literature suggests that many users may have different passwords to
access a computer disk protected by its package. If I were buying it in bulk I
would certainly want to know more about how the key management is done to allow
this. 

Over the long term, leakage of some sensitive data onto swap files is often
a very minor exposure compared to what is protected with an encrypted virtual
disk, and its continued function generally is easier to maintain than anything
that has to deal with both boot and runtime OS environments...and not much
different in training requirements. Remember too there are in Windows some
registry controls that allow the swap file to be wiped on shutdown.

-----Original Message-----
From: full-disclosure-bounces@...ts.netsys.com
[mailto:full-disclosure-bounces@...ts.netsys.com]On Behalf Of Lentila de
Vultur
Sent: Tuesday, February 15, 2005 10:05 AM
To: full-disclosure@...ts.netsys.com
Subject: [Full-Disclosure] harddisk encryption


hi,

sorry for my late answer and for breaking the thread. below you can find the
original post:

<>
i'm evaluating a software that performs harddisk encryption for deploying in
my company. the software in question is utimaco safeguard easy v4.10
(www.utimaco.com) running on w2k.

i am interested in communitty's oppinion about this product. has anyone
performed a detailed analysis of it? i googled around but i couldn't find
much information, except that the version 3.20 sr1 has earned an eal3
certification from the german federal agency for it security. 
</>


thank you for all your answers and suggestions on and off the list.

what i like at safeguard easy are the possibility to encrypt full harddisks,
not only files or partitions, and the boot authentication. Frank Knobbe
suggested encryption plus hard disk from pc guardian - I asked for an
evaluation copy. google suggested also drive crypt plus pack -
www.securstar.com.

imho, the main disadvantage of pgpdisk and alike compared with
full-encryption tools is that valuable data can remain unencrypted in the
swap file or in temporary files outside the container. When using full 
harddisk encryption tools no extra user interaction is required, everything
is done transparently. there is no need for user training.


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