[ajarmoniuk]

but it's easy to triangulate the broadcaster and take measures (imprison, torture, kill).

I lived through the communist era in Poland. Amateur radio stations were banned and prosecuted (you would go to jail), even possession of a CB radio was a crime. Things may be similar in Iran.

[bwarp]

It's not that easy and there are simple anti-triangulation countermeasures you can use. It's possible to drop decoy transmitters/relays, which are easy enough to knock up and are cheap. You can also use refraction to "bounce" HF radio waves off the ionosphere to mask the source. You can scramble the signals. You can disguise the signals as legitimate but include carrier data. There are lots of ways of hiding what you are doing.

As usual, if you don't take precautions, that will happen.

Pirate radio stations were and still are common in the UK, particularly around London. They move around regularly and broadcast for short periods so it's hard to trace or predict a location.

The same conditions apply here.

[wormik]

Umm, you make it look like a trivial problem to solve, which IMHO is not the case when you take the fact you can risk life in prison or death in to the account. I'm from ex-communism country - where a lot of successful broadcastings happened, nevertheless, they got always identified at the end of the day - and then, guess what happened. When you are facing such restrictive conditions, even signal itself is good cause to get you in trouble - no matter whether the information carried is understood/sniffed or not, bounced or not. Anti-triangulation measures you are talking about have IMHO no practical use as long as anyone on the other side is using mobile radio signal detectors. Or if you know about real world application - I'd love to learn about it. Cheers

[bwarp]

It's not trivial - but it's not unsurmountable.

Regarding triangulation, it's about finding the source. The source is hard to track reliably if it moves, especially away from the detection devices or rapidly out of range. Try tracking a broadcast source from a vehicle driving around you in a circle. If it's omnidirectional you'd have to be in the line of sight. If there is interference across the band, selectivity of the RDF recievers is compromised. Radio direction finding is surprisingly painful.

Hint: The anti-triangulation measures are actively used on Clansman radio sets.

[Tichy]

Do you have more resources on that? Occasionally I think about the problem of censorship and free speech and wonder how to enable occupied people to report their plight. So far I could not think of a solution, because I assumed any kind of broadcasting would make the broadcaster an easy target. So what you say interests me (to be fair I am not building anything at the moment, and I am not a hardware person - yet).

[bwarp]

Yes. You need to look up "Electronic Countermeasures". There are plenty of chunks of real info out there on it. Pretty much any form of it is plainly described despite the usual expectation that it's top secret or classified. There are handy forms of point to point encryption which can be easily used on paper and via voice as well. Nice read here on it: http://users.telenet.be/d.rijmenants/en/onetimepad.htm

Also, remember the general rule is that if the broadcaster can become a target, so can the oppressor.

When I finished my EE qual, I actually ended up working as an engineer for one of the more nefarious defense contractors. After about 2 years, I realised that what I was working on was engineering devices to watch people, to keep secrets and kill people. So I gave them the finger. My morals have kept me thinking about this for the last 20 years.

[pnathan]

I came to the conclusion some time ago that I would not work to build devices to harm or spy upon people until it became a matter of doing so or being irresponsible to my family.

Rather work at a Taco Bell than write a censorship program.

[Tichy]

A onetime pad would be a good example of something I would not like to have on me if got grabbed by some oppressive regime. That is the kind of problem I mean.

Tor is not a solution, because it could be found on your computer.

Radiowaves - I don't know, I would also expect them to be easily detectable, but I'll look it up.

[bwarp]

A one time pad can be easily hidden amongst other text i.e. a book printing with some rules applied (third letter of every alternate sentence).

[Finster]

I think I saw this on Max Headroom.

[yread]

I would guess that Internet without HTTPS and SSL is much more traceable than a radio. Also if the authorities don't know there is encrypted radio communication going on they would have hard time finding out about it

[VMG]

I'd imagine that in principle, any wireless communication with simple technology and therefore little infrastructure is still more robust than complex, wired technology with high infrastructure needs.