[Dshield] DI-624 encryption - Run it if you have it!

Chuck Rothauser chuckr at keywestkeys.com
Wed Feb 25 20:12:05 GMT 2004


breezenet does sell products using FHSS but the thruput is about 3 Mbs.

i am working on a PhD dissertation which focuses on improving the
performance and security at the network wireless to wired interface.....

----> Chuck Rothauser

"Tomorrow is a new day and you never know what the tide will bring"


----- Original Message -----
From: "John Holmblad" <jholmblad at aol.com>
To: "General DShield Discussion List" <list at dshield.org>
Sent: Wednesday, February 25, 2004 1:45 PM
Subject: Re: [Dshield] DI-624 encryption - Run it if you have it!

> Rick,
> re: your comment on using frequency hopping for additional security:
> Although the 802.11 standard supports several physical layer standards,
> Direct Sequence Spread Spectrum (DSSS), Frequency Hopping Spread
> Spectrum (FHSS), infrared, and Orthogonal Frequency Division
> Multiplexing (OFDM - this method was added to the standard as a part of
> both 802.11a and 802.11g in ~2001 to support higher data rates up to  54
> mbps, see: http://www.wave-report.com/tutorials/OFDM.htm)  virtually all
> of the commercial products of which I am aware use either  the DSSS
> method (802.11 and 802.11b) or the OFDM method (802.11a) or both DHSS
> and OFDM (802.11g). With the DHSS method the spreading sequence (an 11
> bit barker code) is standardized and is the same for all radios. Thus
> spread spectrum is not used for message privacy but as a means for
> maintaining satisfactory signal to noise (S/N) ratio  while sharing the
> channel in unlicensed radio bands where there may be other signals
> (cordless telephones, microwave ovens, etc.) on specific frequencies in
> the same band. If different transmitter-receiver pairs were using
> different and more complex spreading codes from those used in the case
> of DSSS, then such a multiplexing method would be referred to as Code
> Division Multiple Access or CDMA, like we see in some of the mobile
> wireless networks, especially in the US.
> I would be interested to learn if there are commercial products deployed
> using FHSS. However I should point out that even with FHSS as defined
> within the 802.11 standard, the hopping sequence is fixed by region of
> the world  and does not provide a means to assure any kind of message
> privacy.
> I suspect that with the introduction of 802.11b which increased the
> channel data rate to 11 mbps versus the 802.11 FHSS maximum data rate of
> 4.5 mbps that, in the end, 802.11b and consequently DSSS won out
> commercially over 802.11 FHSS. Better still, in terms of throughput at
> least, are the OFDM based standards, 802.11a and 802.11g, both of
> which, as mentioned above, support the much higher 54 mbps maximum data
> rate.
> --
> Best Regards,
> John Holmblad
> Televerage International
> (H) 703 620 0672
> (M) 703 407 2278
> (F) 703 620 5388
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