Re: FYI: More on WebTV security

--- begin forwarded text


X-Sender: dstoler@gptmail.globalpac.com
Mime-Version: 1.0
Date: Tue, 13 Oct 1998 05:38:59 -0700
To: Pablo Calamera <pablo@microsoft.com>, rah@shipwright.com,
        mac-crypto@vmeng.com
From: dstoler@globalpac.com (dstoler)
Subject: Re: FYI: More on WebTV security
Cc: jimg@mentat.com

Dear all,

This message discusses Microsoft's recent press release where they announce
unlimited 128 bit RC4 export approval for WebTV users in Japan and the UK
with no key escrow. They announce secure email between WebTV users in
addition to security for financial services, web shopping, etc.

http://www.microsoft.com/presspass/press/1998/Oct98/EncryptionPR.htm (See
the end of this message for key paragraphs of the press release.)

I rarely post messages on the crypto mailing lists. I am sufficiently
disturbed by Microsoft's recent WebTV press release that I feel compelled
to comment.

The press release implies that there is secure end-to-end email between two
WebTV customers.

Perhaps I am overly cynical, but I am guessing that they are using SSL
(TLS) from a web based email application on the client to WebTV's servers.
I presume email data is decrypted at the servers, then re-encrypted to the
recipient when she uses the WebTV client to read email.

This approach would allow access to private email at the servers by WebTV
employees or law enforcement agencies.

Note the careful use of the phrases "unauthorized party" and "without
posing undo risks to national security and law enforcement" in the press
release.

I believe that WebTV's email security is directly coupled to their ability
to establish and enforce good security policy within their operation and
the trustworthiness of the employees who have access to sensitive data.

I am concerned that carefully constructed wording of Microsoft's press
release implies stronger email security than really exists. I hope I am
wrong.

David Stoler


Key paragraphs from Microsoft's press release:

WebTV Networks has been granted the first export license to use strong
128-bit encryption for any user and any application in Japan and the United
Kingdom. So, for example, an e-mail message with personal information sent
from a WebTV subscriber in Japan to a second WebTV subscriber in Japan will
be sent securely because there is no known technology by which an
unauthorized party could intercept and decipher it.

Therefore, as part of the WebTV Network, the WebTV-based Internet terminal
(starting at under $100) is now the most secure communications device
available from a U.S. company.

"WebTV Networks' export approval is a significant step for industry and
reflects the U.S. government's commitment to promoting e-commerce abroad,"
said William Reinsch, U.S. undersecretary for export administration. "The
WebTV Network provides secure communications for its customers and partners
without posing undue risks to national security and law enforcement."

--- end forwarded text


-----------------
Robert A. Hettinga <mailto: rah@philodox.com>
Philodox Financial Technology Evangelism <http://www.philodox.com/>
44 Farquhar Street, Boston, MA 02131 USA
"... however it may deserve respect for its usefulness and antiquity,
[predicting the end of the world] has not been found agreeable to
experience." -- Edward Gibbon, 'Decline and Fall of the Roman Empire'

Has anyone hacked WebTV to enable a terminal to connect to a plain vanilla
ISP (or better yet a local ethernet) or is it inexorably tied to their
network of proxy servers? I get the impression that like a Newton or any
other graphically limited device a WebTV browser would have to be aided by
a proxy server that translates the content to more amenable form before it
can take a crack at it. If it were possible to divorce it from their
service it might be a nifty device for less than $100. This would become
especially appealing if 128 bit crypto were thrown into the bargain.

Steve Bryan
Vendorsystems International
email: sbryan@vendorsystems.com
icq: 5263678
pgp fingerprint: D758 183C 8B79 B28E 6D4C  2653 E476 82E6 DA7C 9AC5

On Wed, Oct 14, 1998 at 03:23:45AM -0700, Bill Stewart wrote:
> At 06:32 PM 10/13/98 -0700, SDN wrote:
> 
> >More relevant to the list, the threat model for the WebTV service/box is
> >primarily concerned about loss of user data, forgotten passwords, and
> >unsecured data over the public internet.  It's not worried about privacy
> >from WebTV insiders.
> >As a result, all user data is stored on the service, traffic to and from the
> >box is encrypted, and data isn't hidden from the customer care people.
> 
> If it's not secure against insiders, then it's not only not secure against cops,

I'd say it's definitely not secure against law enforcement.  That's probably
the primary reason why the boxes got export approval with 128-bit crypto.
It's just so much easier to ask the service operators what a user has been
up to, check the logs, and go...

That's why I said that the threat model wasn't something a cypherpunk would
be happy with.  There just isn't any protection against an attacker who
looks legitimite to Microsoft.

> it's also not secure against crackers, unless Microsoft hsa let the
> WebTV folks do a very good job of security.

This is less clear.  The service predates the buyout, and it hasn't (yet)
migrated to NT.  The people who run and maintain it are very competent
(at least the ones I know personally), but anyone can make mistakes,
espescially under the pressures of a startup environment.

Jon Leonard

Again, the above are my opinions.  WebTV's opinions may be entirely different.

At 06:32 PM 10/13/98 -0700, SDN wrote:

>More relevant to the list, the threat model for the WebTV service/box is
>primarily concerned about loss of user data, forgotten passwords, and
>unsecured data over the public internet.  It's not worried about privacy
>from WebTV insiders.
>As a result, all user data is stored on the service, traffic to and from the
>box is encrypted, and data isn't hidden from the customer care people.

If it's not secure against insiders, then it's not only not secure against cops,
it's also not secure against crackers, unless Microsoft hsa let the
WebTV folks do a very good job of security.



				Thanks! 
					Bill
Bill Stewart, bill.stewart@pobox.com
PGP Fingerprint D454 E202 CBC8 40BF  3C85 B884 0ABE 4639

On Tue, Oct 13, 1998 at 11:58:37AM -0500, Steve Bryan wrote:
> Has anyone hacked WebTV to enable a terminal to connect to a plain vanilla
> ISP (or better yet a local ethernet) or is it inexorably tied to their
> network of proxy servers? I get the impression that like a Newton or any
> other graphically limited device a WebTV browser would have to be aided by
> a proxy server that translates the content to more amenable form before it
> can take a crack at it. If it were possible to divorce it from their
> service it might be a nifty device for less than $100. This would become
> especially appealing if 128 bit crypto were thrown into the bargain.

The WebTV units are in fact tied to the WebTV service.  You can use another
ISP to reach the service, though, at a reduced cost.  (Search for OpenISP
at webtv.net.)  Retrofitting ethernet onto a box isn't practical.

The proxy servers do transform data, but I don't think the software in the
box requires it.  My understanding was that the transformations were just
for faster downloads, and did things like rescale images.  It doesn't matter
much, because there isn't a way to avoid using them.

More relevant to the list, the threat model for the WebTV service/box is
primarily concerned about loss of user data, forgotten passwords, and
unsecured data over the public internet.  It's not worried about privacy
from WebTV insiders.

As a result, all user data is stored on the service, traffic to and from the
box is encrypted, and data isn't hidden from the customer care people.

If that doesn't fit what you want out of it (and it doesn't seem very
close to a consensus cypherpunks threat model), don't get one.  I think
it's the best attempt at an easy-to-use network computer on the market,
but I don't use one myself.  It's not what I want.

Jon Leonard

The above opinions are mine and not WebTV's.