The "modern" game Microsoft plays is boring. It acknowledges and thanks researchers, often accepts worst-case assessments of impact, and fast-tracks fixes. What they don't understand is that our stories need an antagonist, someone we can name and pillory. Thanks, Claire Cranton at GSM.com, for giving us one.
Microsoft has more experience handling security disclosures than any other organization. The GSM manufacturers apparently have very little comparable experience. I'm just contrasting the two.
“What he is doing would be illegal in Britain and the United States.”
Hmm, guess which two countries he is not doing this in. I am not sure how this is relevant, except to say, "oh fuck." (If you can't attack the argument, attack the person who's arguing.)
To do this while supposedly being concerned about privacy is beyond me.
Now I know for sure that I need to encrypt my calls in another way. Before this announcement, I figured it was handled for me; I didn't assume that criminals had already broken the crypto and had kept the information secret. Now I am sure they have, and that my non-encrypted calls are obviously being monitored. (I exaggerate a bit, but it's clear how this disclosure enhances my privacy.)
Not sure why the GSM folks are taking this so seriously. Computers are fast. 64-bit encryption has been unsafe for nearly a decade. Everyone knows that this was going to happen eventually.
Edit: after reading the slides, I am really amazed by this. I remember when I was a kid and I used to listen in on cordless phones and baby monitors with my radio scanner. It was really, really interesting. The thought of sitting on the train and listening to both sides of people's cell-phone calls appeals to me in a way that I can't quite explain.
In fairness, or whatever, the problem with A5/1 isn't simply that it's got a 64-bit key, but that it's a uniquely bad stream cipher prone to linear equation-style attacks and precomputation. Nate, Colin, or Bruce may smack me down for saying this, but I don't think you can apply the same attacks to, say, RC5.
For roughly a decade, pretty much anyone who attended more than one local 2600 meeting got the tech demo on snooping cell phone calls --- they were analog. Everything old is new again. It's nice that encrypted digital calls were so successful that the loss of their security is major news.
Yeah, you are right. The impression that I got from the NYT article was that this was "given a trace and a bunch of computers, you can get the voice data... maybe, eventually", but the impression that I get from the talk is that it is actually realtime. That requires weaknesses in the crypto that are embarrassing for anything 1980s or 1990s vintage. I don't think this attack would be feasible if they used DES instead. (I will defer to you or cperciva for that one, however :)
what i got from the 3c talk is that the data stream is on the order of 80MB/s (tx/rx, because they need to record the entire spectrum due to frequency modulation) and that currently they have not found a way, it seems due to lack of fpga programming skillz, to decode in real time. it seems like they are recording and then decoding some time later via their 2TB lookup table. Even with the 64bit keyspace the lookup table is 2TB because its a rainbow lookup which means that only certain values at certain intervals are stored.
The point of the presentation is not that GSM has been broken; it's to make it so blatantly, obviously, publicly broken that the public (i.e., corporate IT departments) will have to pay attention.
It seems likely that to the extent that things like the GSS-ProA suitcase interceptors crack A5/1, they do it with special-purpose hardware. A practical software attack is news.
- If you have an iPhone 3G signal (for example), you're using UMTS (not GSM), which has longer encryption keys (128-bit) and an enhanced protocol. Brute-forcing this keyspace (as in the CCC paper) is unlikely, though they mention the cipher (KASUMI) is "academically broken".
- Neither system has end-to-end privacy. Data is encrypted to your operator's equipment. All other hacks apply.
NYT: In 2007, the GSM developed a 128-bit successor to the A5/1, called the A5/3 encryption algorithm, but most network operators have not yet invested to make the security upgrade.
As far as I can determine, this is wrong. Europe has UMTS broadly deployed and the US came late to this party.
I'm not sure of the specific relevence to this article, since it was a good while ago i listened the details mostly escape my memory, but you can grab a good background on why GSM is insecure listening here: http://twit.tv/sn213
They are down to ~2TB for rainbow tables, calculated on GPUs, making cracking feasible. Also, the code and knowledge is put into the public: http://reflextor.com/trac/a51/wiki
“This is theoretically possible but practically unlikely,” said Claire Cranton, a GSM spokeswoman, noting that no one else had broken the code since its adoption. “What he is doing would be illegal in Britain and the United States. To do this while supposedly being concerned about privacy is beyond me.”
A set of incredible admissions.
* This is theoretically possible but practically unlikely
GSM 64bit encryption is broken. Not theoretically but actually. The likelihood of it happening to someone now depends on the value of the calls.
* no one else had broken the code since its adoption.
And now they have, that's the point
* would be illegal in Britain and the United States
I don't think criminals are deterred by such niceties and they are hardly likely to reveal their source while extorting money from me or making insider trades
* To do this while supposedly being concerned about privacy is beyond me
Knowing that my handset can be eavesdropped by people outside of the law is the ultimate privacy concern. That you don't understand this is beyond me.
> The association noted that hackers intent on illegal eavesdropping would need a radio receiver system and signal processing software to process raw radio data, much of which is copyrighted.
Again, copyright infringement would be very low on the list of criminal organisations.
Your response beggars belief, except it is perfectly reasonable viewed through the lens of PR.
Right now there are employees of GCHQ, NSA, Mossad, whatever the KGB is called this week, smirking at that assertion, they've probably had the capability for years. All this does is level the playing field a little.
I know for a fact that real-time A5/1 has been privately available commercially since at least 2006. It is my understanding from talking to a relevant engineer that if the algorithm wasn't known-broken when released, it was broken by intelligence services within the first year.
In conclusion, don't talk on cell phones when you're talking about sensitive things. In some locations (mid east), it has compromised you for years.
So you sent an e-mail to some public relations person at an interest group (gsm.ORG btw). You should approach your service provider or handset manufacturer, who (in theory) could take direct action as described in the presentation from ccc. This is one of the reasons for having an open phone.
Please find below my full reply to the journalist's enquiry.
Regards,
Claire Cranton.
~~~~~~~~~~~~~~~~~~~~~~~~
We have been asked about this a number of times and the industry position is below. A5/1 has been in existence for a long time and so we have developed A5/3 as a migratory strategy for operators. However what I'd like to stress is that this activity is highly illegal and in the UK would be a serious RIPA offence as it probably is in most countries, it is likely also to contravene IPR. The GSMA heads up a security working group which looks at all issues re security and this isn't something that we take lightly at all.
Best wishes
Claire
STATEMENT ON GSM ENCRYPTION
GSM networks use encryption technology to make it difficult for criminals to intercept and eavesdrop on calls. On most GSM networks, the communications link between the handset and the radio base station uses the A5/1 privacy algorithm to scramble the signal.
Over the past few years, a number of academic papers setting out, in theory, how the A5/1 algorithm could be compromised have been published. However, none to date have led to a practical attack capability being developed against A5/1 that can be used on live, commercial GSM networks.
Reports of an imminent GSM eavesdropping capability are common. The GSMA, which welcomes research designed to improve the security of communications networks, routinely monitors the work of groups in this area. In 2007-8, a hacking group claimed to be building an attack on A5/1 by constructing a large look-up table1 of approximately 2 Terabytes - this is equivalent to the amount of data contained in a 20 kilometre high pile of books. In theory, someone with access to the data in such a table could use it to analyse an encrypted call and recover the encryption key.
Another group has announced similar plans in 2009. However, before a practical attack could be attempted, the GSM call has to be identified and recorded from the radio interface. So far, this aspect of the methodology has not been explained in any detail and we strongly suspect that the teams attempting to develop an intercept capability have underestimated its practical complexity. A hacker would need a radio receiver system and the signal processing software necessary to process the raw radio data. The complex knowledge required to develop such software is subject to intellectual property rights, making it difficult to turn into a commercial product.
Today, mobile networks are typically configured to optimise call set-up times, capacity and other aspects related to operational efficiency. But mobile operators could, if it ever proved necessary, quickly alter these configurations to make the 1 A definition of a lookup table is available at http://en.wikipedia.org/wiki/Lookup_table interception and deciphering of calls considerably harder. Moreover, intercepting a mobile call is likely to constitute a criminal offence in most jurisdictions.
All in all, we consider this research, which appears to be motivated in part by commercial considerations, to be a long way from being a practical attack on GSM. More broadly, A5/1 has proven to be a very effective and resilient privacy mechanism. By comparison, inexpensive and readily available radio scanners could be used to intercept calls on the analogue cellular networks that pre-dated GSM and which did not use encryption.
The mobile industry is committed to maintaining the integrity of GSM services and the protection and privacy of customer communications is at the forefront of operators' concerns. The GSMA has been working to further enhance privacy protection on GSM networks and has developed a new high-strength algorithm, A5/3. Over the past decade, export control agencies have removed many of the traditional barriers to the sale of cryptographic technologies enabling the development and use of A5/3. This new privacy algorithm is being phased in to replace A5/1.
- Show quoted text -
The GSMA represents the interests of the worldwide mobile communications industry. Spanning 219 countries, the GSMA unites nearly 800 of the world's mobile operators, as well as more than 200 companies in the broader mobile ecosystem. Visit www.gsmworld.com and www.mobileworldlive.com for more information.
It also produces the premier industry events including Mobile World Congress in Barcelona www.mobileworldcongress.com and Mobile Asia Congress www.mobileasiacongress.com
I agree... it's a ridiculous description, and obviously the point is to confuse a less technical person into thinking 2 TB requires more than a single top-of-the-line HDD to store.
Taking your request literally, 2 terabytes is equivalent to (roughly) one-37th of the currently-digitized items in the printed collection in the Library of Congress. Good day. :)
> The complex knowledge required to develop such software is subject to intellectual property rights, making it difficult to turn into a commercial product.
Intellectual property rights aren't a security mechanism.
If the people in power at GSM are this clueless about security, I don't think they will ever be capable of producing anything usably secure.
Did you know that if you took the five pound notes it cost to buy 2tb of disk drive and laid them out end to end it would go from here to the end of my desk and back. Your book comparison is hilarious.
Who on earth is suggesting that anyone is going to make this into a commercial product?
I'm not sure whether you are naive or you think I am.
You should be giving FULL DISCLOSURE to your users, not platitudes.
It really is shameful that you are just trying to cover your arses.
http://chargen.matasano.com/chargen/2009/4/1/how-to-hidehhha...
The "modern" game Microsoft plays is boring. It acknowledges and thanks researchers, often accepts worst-case assessments of impact, and fast-tracks fixes. What they don't understand is that our stories need an antagonist, someone we can name and pillory. Thanks, Claire Cranton at GSM.com, for giving us one.