[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]

Re: PCS Encryption?



Greg Rose wrote:
>
> The three different digital standards in North America are TDMA,
> CDMA, and GSM (in NY and DC only AFAIK).

GSM is also a Time Division Multiple Access (TDMA) system. In it's 
original form it uses specrum around 900 MHz, which I believe not to be 
available in the US. Shame really, I can roam with my GSM phone over 
pretty much the rest of the planet ... except the US.

Anyway, there are two higher frequency derivatives, PCS1800 & PCS1900, 
which have been deployed in the US. I'm not involved directly in the US 
market so I'm not sure where. I assume however that these are the 
systems to which Greg refers.

> Newer analog phones use at least some of this, but I don't know much
> about them. I'll ignore GSM.
              ^^^^^^^^^^^^^^^
Aww shame ;)

> The conclusion is that neither way of doing it is truly
> cryptographically strong, but both are a lot better than
> listening to Princess Di call Newt "Squidgy" on a Radio Shack
> scanner.

GSM uses the A5 algorithm which *is* cryptographically strong, but is 
unfortunately considered to be top secret stuff. If, however, you were 
to pick up a copy of "Applied Cryptography, 2nd Edition" by Bruce 
Schneier you may find something of interest.

I hope that you'll work out from my .sig why I can't say much more.

Hope this helps

Andy M

-- 
___________________________________________________________________

Andrew Meredith
Senior Systems Engineer        Tel:              +44(0) 1793 565377
Network Engineering Tools Grp  Fax:              +44(0) 1793 565161
GSM Products Division         Page:              +44(0)  839 421153 
Motorola                      SMTP:       [email protected]
16, Euroway, Blagrove         X400:           [email protected]
Swindon, SN5 8YQ, UK           SMS:   [email protected]
___________________________________________________________________