[3678] in cryptography@c2.net mail archive
Re: Is a serial cable as good as thin air?
daemon@ATHENA.MIT.EDU (Arnold G. Reinhold)
Tue Dec 1 12:26:51 1998
In-Reply-To: <Pine.BSF.3.96.981130134508.1490C-100000@support.mfn.org>
Date: Mon, 30 Nov 1998 22:55:45 -0500
To: Missouri FreeNet Administration <measl@mfn.org>,
Dianelos Georgoudis <dianelos@tecapro.com>
From: "Arnold G. Reinhold" <reinhold@world.std.com>
Cc: cryptography@c2.net
I am uncomfortable with the tone of this thread. There is nowhere near
enough information provided in Mr. Georgoudis' posting to conclude that
hisbank's existing floppy disk transfer scheme is secure, much less render
an opinion on the impact of a serial connection.
Most computer systems can be broken down in to a series of components, like
links on a chain, and analyzed individually. If all the links are ok, the
system should work. Cryptography is not like that. Crypto is more like a
condom where a single hole can cause a failure without the user even being
aware of the problem until it is too late. A careful analysis of Mr.
Georgoudis' total system, including threat models, acceptable levels of
risk, audit possibilities, etc. is needed to reach a sound conclusion.
Arnold Reinhold
At 1:46 PM -0600 11/30/98, Missouri FreeNet Administration wrote:
>Why not keep the "ThinAir" concept, and use an optically-isolated link?
>A one-way connection: just like your floppies...
>
>On Sun, 29 Nov 1998, Dianelos Georgoudis wrote:
>
>:Date: Sun, 29 Nov 1998 22:20:29 -0600
>:From: Dianelos Georgoudis <dianelos@tecapro.com>
>:To: cryptography@c2.net
>:Subject: Is a serial cable as good as thin air?
>:
>:
>: We are installing home banking systems where the Internet Server
>: is separated from the bank's computer center by air. Data is moved
>: periodically back and forth using low tech but dependable floppy
>: disks that carry only encrypted data (the principle of red/black
>: separation is implemented by loading only encrypted data on the
>: server). This "air-wall" is an effective way to stop hackers from
>: penetrating the bank's computer center using its Internet
>: services. This works quite well with services such as users'
>: credit-card queries.
>:
>: Now, we have a potential client insisting on on-line transaction
>: capability. One possible solution is to connect the Internet
>: server with a PC on the bank's private network using a serial
>: cable. We would write our own transmission protocol. The PC
>: working on the bank's network would run a memory resident program
>: that services the serial port and will discard any blocks that do
>: not decrypt properly or have an invalid structure (only blocks
>: that decrypt into the correct data structure would be processed at
>: all). Here is the question: Is this as good as thin air? Can you
>: see any way a hacker could use such a connection to penetrate the
>: bank's network?
>:
>:
>:Dianelos Georgoudis
>:email: dianelos@tecapro.com
>:http://www.tecapro.com
>:
>:
>
>Yours,
>J.A. Terranson
>sysadmin@mfn.org
>support@mfn.org
>
>--
>If the Government wants us to behave,
>they should set a better example!
