[Cryptography] Tempest and limits on receiving

[Charlie Jonas]

On 2017-04-04 20:34, Bob Wilson wrote:
> Several posters seem to think that in the USA there are no restrictions
> on just listening, e.g.
>> In the US laws only prohibit active interference, not passive shielding.
> Have you tried to buy a shortwave radio that covers all of the
> frequencies from, say, 100MHz to 10GHz? There are quite a few receivers
> that say they do that, until you look at the footnote saying that
> reception of certain frequencies is disabled, because the disabled
> frequencies are used by some cell 'phones. I admit I don't know where
> the law might be, but something is certainly causing all those
> manufacturers to remove that capability from their receivers. This
> applies to units sold in the USA but built elsewhere as well as those
> built here.
> 
> Since we don't have vans on the streets looking for radiation from
> receivers (the way Britain for a long time enforced the requirement to
> buy a radio receiving license), the easy way to enforce such a
> restriction is to place it on all equipment made for sale. You could
> presumably build your own receiver with whatever reception frequencies
> and modes you wanted, and wait to see if any such restrictions are being
> enforced in some other way.
> 
> (Note that I am specifically saying "receivers". Many of them are built
> into "transceivers" that combine a receiver and a transmitter,
> frequently designed for ham radio use, but the (a) limitation is on
> reception and (b) if the company makes a separate receive-only device
> for those frequencies, the same restriction will be included.)
> 
> Bob Wilson
> 
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My understanding of UK law is that it's illegal to listen to *any*
channel that's not meant for public broadcast. You are, however, legally
allowed to listen in using receive-only equipment to any channel which
does have a public broadcast license or that is intended for general
consumption by the public (ie. FM broadcast radio, Ham & CB radio, WX &
Nav traffic).

That being said nobody has been prosecuted for this type of offence in
the UK AFAIK. And they don't actively police this in the same way they
to the television license fee.

-- 
Charlie Jonas                 chtj2 at cam.ac.uk