--Adonis Comment--
I do not agree with some of truecrypt comments specially the quoted text below.

What if you had  created a virtual disk  and give that to  someone. That someone
use it as his/her own disk and  decided to change the password because they  own
the disk  now (You  give them  to them  with the  pass). So  they did change the
passowrd, but the originator  can still access that  disk if he/she replace  the
passphrase  bytes in  the binary  file. So  I consider  this an  attack on  data
INTEGRITY and  data AVAILABILITY since the legitimate user will be denied access
to the disk after replacing the passphrase bytes.

-- End Comment--

====================================================================
"In conclusion, this is not a "security bug", but design/feature. Also,
to exploit the design, the adversary would have to know your password
first (or have your keyfiles). That means, for example, that he would
capture it using a keystroke logger. If that was the case, then all
security would be practically lost on that machine."
====================================================================


RE: A Nasty Security Bug that affect PGP Virtual Disks & PGP SDA , PGP 8.x & 9.x and Truecrypt. May 26 2006 09:14AM
ennead (at) truecrypt (dot) org [email concealed] (ennead truecrypt org)
Hello,

This is an official response from the TrueCrypt development team.

First, this is not a security bug. It is a known, documented and
expected feature. It is utilized, for example, for the volume header
backup/restore operation.

Quotes from the TrueCrypt documentation:

"WARNING: Restoring a volume header also restores the volume password
that was valid when the volume header backup was created."

Quote 2:
"Note that if an adversary knows your password and has access to your
volume, he may be able to retrieve and keep its master key. If he does,
he may be able to decrypt your volume even after you change its
password (because the master key was not changed). In such a case,
create a new TrueCrypt volume and move all files from the old volume to
this new one."

Sincerely,
Ennead
TrueCrypt Foundation

====================================================================
Addendum May 26 2006 10:47AM
ennead (at) truecrypt (dot) org [email concealed] (ennead truecrypt org)

Addendum to my previous letter:

Note that this design (master key encrypted with header key) is common
and has been used for many years by many products (for example,
Scramdisk, E4M, etc.)

The main advantage of the design is that the user can change his
password within a few seconds without having to re-encrypt the entire
volume (which could take even days or weeks).

In case of TrueCrypt, this also allows administrators in large
corporations to "reset" passwords when a user forgets his password.
This is described in the manual and in the FAQ:

Quote from the TrueCrypt FAQ:

"Q: We use TrueCrypt in a corporate environment. Is there a way for an
administrator to reset a volume password when a user forgets it (or
when he or she loses the keyfile)?

A: There is no ?back door? implemented in TrueCrypt. However, there is
a way to ?reset? a TrueCrypt volume password/keyfile. After you create
a volume, backup its header (select Tools -> Backup Volume Header)
before you allow a non-admin user to use the volume. Note that the
volume header (which is encrypted with a header key derived from a
password/keyfile) contains the master key with which the volume is
encrypted. Then ask the user to choose a password, and set it for
him/her (Volumes -> Change Volume Password); or generate a user keyfile
for him/her. Then you can allow the user to use the volume and to
change the password/keyfiles without your assistance/permission. In
case he/she forgets his/her password or loses his/her keyfile, you
can ?reset? the volume password/keyfiles to your original admin
password/keyfiles by restoring the volume header (Tools -> Restore
Volume Header)."

In conclusion, this is not a "security bug", but design/feature. Also,
to exploit the design, the adversary would have to know your password
first (or have your keyfiles). That means, for example, that he would
capture it using a keystroke logger. If that was the case, then all
security would be practically lost on that machine.

Sincerely,
Ennead
TrueCrypt Foundation
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