Re: [Discuss-gnuradio] "A scanner with a digital output" address@hidden pwright.com: @stake wows the wireless rubes...]

[Dave Emery]

On Thu, Mar 21, 2002 at 07:32:35AM -0500, Nick Waterman wrote:
> Sure...
> 
> Wandering offtopic a bit, and sounding like I'm advertising my company a bit
> too much, but...
> 
> 
> The one that CAN be sniffed is the "blackberry internet edition" bought by
> the man-on-the-street. There's no corporate BES to do the encryption, email
> is sent across the (insecure) internet in plaintext SMTP to RIM, and sent in
> plaintext to the carriers, across the air, to the pagers. There's no
> realistic way to exchange keys and little point anyway. I suppose some sort
> of public/private method would theoretically be possible, but seems
> pointless considering this particular solution is supposed to be no more
> secure than any other 2-way pager - just the added convenience of being
> "real email". This is NOT supposed to be used for secure corporate mail -
> for that you'd buy the more expensive but more popular BES enterprise
> version, and use the end-to-end encrypted service.
> 

        Sort of sad that the usual rationale for not LINK encrypting a very
vulnerable radio link has bit again as it so very often does.   Best as
enemy of good enough seems a very serious problem in this area.

        Sure link encryption of the rf link does not protect much at all
against all the other possible ways of intercepting the traffic (on the
Internet in particular), and sure the right way to do this is what you
supply to corporate customers (which I understand is more or less done
quite well and clearly indicates that RIM understands the issues).

        But simply encrypting the public user traffic with either a
fixed default key based on a hash of the user ID and addresses and
device serial and a large secret salt known only to RIM or a RIM chosen
random key associated with the device would keep out 99.99% of potential
rf link attackers.  Clearly this would make randomly or casually
browsing public user Blackberry traffic with a scanner and laptop (very
easy to do now as the required software has been floating around on the
Internet for about 3 or 4 years) essentially impossible.   And doing
this seems such a useful social good that it strikes me as sad and
appalling that RIM did not do so since they obviously had all the
firmware and technology in place to handle this both in the Blackberry
itself and their network.

        In fact, even encrypting the traffic with a fixed key based just
on a hash of address and serial number and a salt value contained in the
Blackberry ROM, weak as it sounds, would require an attacker to know the
device address and the (not sent over the rf link) serial number and the
salt value which would eliminate all but those with very specific 
and targeted interest.

        But for some reason for the last 30 years the attitude in lots
of places seems to be - if it isn't completely end to end secure against
very effective and targeted attack by attackers with large resources  it
isn't worth securing at all even on radio links that can be completely
anonymously and untraceably intercepted for tens of miles (or more)
around the transmitting sites.  So the traffic gets sent in the clear
where it can be intercepted by virtually anyone with minimal skill and
equipment while if the link was half decently link encrypted it would at
least take a quantum step upwards in resources, information and skill to
get at the traffic.

        And too often the actual end user is constrained by economics and
other circumstances and simply cannot afford to implement and use high
grade end to end security, or doesn't even appreciate the need for it
and therefore puts his sensitive traffic in the clear on a trivially 
intercepted link with absolutely no security at all.   And this is sad,
when there could be at least SOME security there at low cost to the
carriers involved.

        And given the description of the two classes of Blackberry
customer, I cannot help but wonder if LEAs and TLAs had something to do
with the decisions involved - clearly very few if any corporate
customers with BES systems and the whole 9 yards inside their firewalls
are likely to be criminals (or at least low level stupid criminals
likely not to get COMSEC right), whilst a significant (albiet small)
percentage of public Blackberry users will be drug
dealers/criminals/terrorists of great interest to LEAs and intelligence
agencies, and probably at least some of those people will assume that
because corporate Blackberries are secure and encrypted  theirs are too
and there is no chance of LEAs legally or extra-legally intercepting
their traffic.   Thus keeping the rf link completely open helps the
watchers watch, and is something that they can be presumed to have
quietly pressured to have happen.

-- 
        Dave Emery N1PRE,  address@hidden  DIE Consulting, Weston, Mass. 
PGP fingerprint = 2047/4D7B08D1 DE 6E E1 CC 1F 1D 96 E2  5D 27 BD B0 24 88 C3 18