GSM - A5 Strength

[Alec Muffett - SunLabs]

 >Why is there so much discussion about the security of GSM, which has a
 >fairly well protected radio link, while many people use at home an
 >analog cordless phone with either no encryption at all or a silly
 >analog frequency inversion scheme that every owner of a scanner and a
 >PC soundcard can descramble instantly?

In the interests of not trashing the reputation of scanner owner/users
any further than the media has already done, just a quick note:

Since most analogue cordless phone base-stations operate around
1600KHz FM, you wouldn't actually need a sexy VHF/UHF scanner to
receive them.

These transmissions are actually only just above the medium-wave
frequency band, and any half-decent shortwave radio should be capable
of receiving them, either in native FM, or in AM by tuning
off-frequency and picking up the AM edge-effect.

Spread-spectrum.  Verb. sap.

	- alec

-- 
    alec muffett, sun microsystems laboratories, alec.muffett @ uk.sun.com
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