From: "Christian D. Odhner" <cdodhner@indirect.com>
Date: Sat, 30 Apr 94 16:14:10 PDT
To: A.W.S.Helwig@ET.TUDelft.NL
Subject: Secure Device - Plaintext/Cyphertext size difference?
In-Reply-To: <01HBRTDS3EQ0935JW0@delphi.com>
Message-ID: <Pine.3.89.9404301643.A6094-0100000@id1.indirect.com>
MIME-Version: 1.0
Content-Type: text/plain


I just started using this program (secure device) yesterday. I love the 
concept, however there is something that bugs the hell out of me... I set 
it up for a 30-meg encrypted 'volume', and the file is indeed about 30 
megs. However when I 'log in' to it, a dir shows only about ten megs of 
space. I tried creating an additional secure device volume, and this one 
was 25 megs on the outside and a bout 8 megs on the inside.  From what I 
glean from Applied Cryptography, IDEA usualy produces cyphertext 
approximately the same size as the cleartext, right? so why the massive 
difference in available space?

Happy Hunting, -Chris.

______________________________________________________________________________
Christian Douglas Odhner     | "The NSA can have my secret key when they pry
cdodhner@indirect.com	     | it from my cold, dead, hands... But they shall
pgp 2.3 public key by finger | NEVER have the password it's encrypted with!"
cypherpunks         WOw            dCD           Traskcom          Team Stupid
  Key fingerprint =  58 62 A2 84 FD 4F 56 38  82 69 6F 08 E4 F1 79 11 
------------------------------------------------------------------------------

On Sat, 30 Apr 1994, Mike Ingle wrote:

> Secure Drive, the disk encryption system written by me and improved by
> Edgar Swank, has been completely rewritten by two programmers in the
> Netherlands, Max Loewenthal and Arthur Helwig. I was not aware of this
> until I saw the program yesterday.
> 
> They changed it to Secure Device. It still uses the IDEA algorithm, but
> you no longer have to create a partition! Secure Device uses a file as a
> phantom partition, like Stacker or inDiskreet. It has a .SYS driver of
> about 6K. There is a login program, or you can use another TSR which does
> a pop-up login prompt. There is also keyboard logout and time-delay logout.
> 
> Another advantage of Secure Device is ease of backup. You just backup the
> container file onto your tape, and the data stays encrypted. Secure Device
> includes source code and is copylefted.
> 
> FTP wuarchive.wustl.edu, /pub/MSDOS_UPLOADS/cryptography/secdev11.arj. 
> 
> --- Mike
> 
>