How secure is GSM?
In particular is it possible to listen in on sms text messages?
Apparently they are sent on the network signalling frequencies? It would be presumably quite easy to listen in on this signal and decode every sms on it?
I am just curious. Perhaps we should avoid sending anything on sms that we would not send on a post card?
At a guess I think GSM phone calls would be more secure than sms?
Thanks very much for any replies.

They are secure enough not to be listened into on ordinary scanners. The police can tap them though if they've got a warrant.

Tap then with a advanced radio scanner or tap them by getting the phone company to send them to a police station?

The question how secure depends on who you want to be secure against. From what I understand GSM compared with most other telecommunications equipment is among the securest out of the box. It is far beyond the scope of most normal people to listen to GSM calls out of the air, as the equipment for one thing is very expensive, and only sold to licensed government agencies. GMS uses a combination of security keys etc which results in very strong encryption between the end user hand set and base station, but obviously someone could intercept the signal at the base station end after it has been unencrypted to get the data.

But im not sure if this applies to SMS - I have not personally heard of any equipment to do this so I really wouldn’t worry about it.

Listening to cordless analogue phones on the other hand is a walk in the park.

Part of the GSM encryption system was hacked a while back A5 Algorithm . In fact when GSM was being developed they intended to use a much stronger Algorithm than they use at the moment. But certain governments weren't very happy about it and it soon got dropped!

A few years ago I did see a website selling a scanner & a laptop alegedly capable of decrypting GSM & given the multi million dollar price tag I suppose it could be true. They would even fly someone out to your country for a demo which would cost you a few thousand dollars! And it was for sale to law enforcement agencies only.

For most part GSM is fairly secure I dont know about SMS though. You can be pretty sure the only people listening in will be Governments and they listen to everything! Echelon

I don't know why but I just have this sneaky suspicion that sms is less secure than phone calls.

v.interesting
hope those strong encryption appears on 3G

Poo if your interseted in the 3G encryption look hereGSM World A5/3 Algorithm which will be more secure apparently.

There is also an audio discussion of GSM security at http://the.wiretapped.net/multimedia/beyondhope/gsm.ra

One thing you may not know is that ALL Mobile Phone calls are listened to and monitored. Computers process the calls listening to words such as "Kill, Bomb, Queen" etc, if it detects enough of the words enough times quite often on numerous phone calls, your call is then put on a special monitoring list and eventually monitored by humans. But this is only mobile calls, not land line calls. Kinda Scary is'nt it?

[blush] Hmm, I wonder if the automatic monitor picks up SMS messages containing the text "...with your bum". [/blush]

RR

Not just GSM, land line calls are monitored too!

That system is called "Echelon" - and if undergound whisperings are to be believed the "Technology Information Centre" in central London run by MI5/MI6 will soon be snooping on your emails/surfing habits.

D.P.