Um guys, A5/3 is completely broken. According to Wikipedia: "In 2010, Dunkelman, Keller and Shamir published a new attack that allows an adversary to recover a full A5/3 key by related-key attack.[5] The time and space complexities of the attack are low enough that the authors carried out the attack in two hours on an Intel Core 2 Duo desktop computer even using the unoptimized reference KASUMI implementation. The authors note that this attack may not be applicable to the way A5/3 is used in 3G systems; their main purpose was to discredit 3GPP's assurances that their changes to MISTY wouldn't significantly impact the security of the algorithm."
Even if A5/3 weren't broken, there are still tower dumps and IMSI catchers, which are a whole lot easier to use than breaking encryption.
Yes A5/3 is better than A5/1, but I call bullshit on this whole article.
>Yes A5/3 is better than A5/1, but I call bullshit on this whole article.
Super pendantic, but the title is 'hardens' not 'makes hard'. If it's better, than it's been hardened. Might not be the best thing available, but that's the meaning of a comparative.
I have T-Mobile, and I have to say, I've been quite happy with it and I've been just waiting for the other shoe to drop. The only negative thing I hear about them is people don't like the coverage area - which doesn't bother me because when I switched to them they were the only company that offered wifi calling (meaning I can comfortably use my phone at work and at home, where I spend 99% of my time, for the first time in 6-8 years).
Do I just have a rosy outlook, or is T-mobile's limited marketshare such a problem that they're somehow disciplined into being an actually good mobile carrier?
Same story here. Have had T-Mo for ~3 years, wouldn't ever switch to one of the other big carriers (I would move to Republic Wireless if I was going to change). My wife moved from Verizon -> T-Mobile last year after finally getting tired of the ridiculous prices from Verizon, and is also very happy.
Coverage is fine. Sometimes on road trips to the beach here in North Carolina we will lose service for say 5-10 miles when we are really in the middle of nowhere (the sprawling metropolis of Elizabeth City, NC in particular gives me trouble). This is acceptable in return for nearly 50% savings and not having to do business with AT&T/Verizon.
Depends on your definition of "actually good". I've been a T-Mobile customer since they first entered the US, and I've generally been happy, but I was incredibly upset when I saw that they started zero-rating "approved" music services[0] .
I have unlimited data, but as a strong supporter of net neutrality, I take issue with that.
I've been a VoiceStream, then T-Mobile customer for over 16 years. There's been ups and downs in the relationship over the years. The most notable "down" was the $800 international roaming charge they refused to remove from my bill a few years back. Even though I really wanted to leave them then, a thorough cost analysis of the competition showed they really were still cheaper...
More recently, the Simple Choice plan they introduced last year which includes "free" international data roaming has ensured I stick with them for even longer. I travel quite a bit, so that + the wifi calling which works pretty much anywhere in the world has been a great thing.
I dropped them many years ago over a similar issue, except in my case I was almost 40 miles from the Canadian borders and picked up a Canaidam tower... They slapped me with a huge fee for international roaming.
This was late 90s, so I think a 10 minute call cost like $150!
A lot of the time, such charges come up because the customer was unaware, not because they used it. I once made a call from whatsapp not realizing it wouldnt go through wifi, and ran up almost $150, but T-mobile was kind enough to remove it off the bill. Just customer-friendliness, more than anything else.
The wife and I took a cruise a few years ago and I tried my damnedest to turn off anything even remotely resembling "yes, you can have a data connection". I wanted to leave my phone on in case something happened with the kids (and so I'd have a watch), I just didn't want it to DO anything other than allow incomming calls. Got home to a $200 phone bill because there was a checkbox somewhere I'd missed and cruise-ship mobile data is abhorrently expensive.
T-mobile is the only carrier in the U.S. with good coverage and unlimited data + iPhone support, so for me it's really my only option. They've been really great so far; only charge what they say they are going to charge, no contract, and no overages. It's incredibly disheartening to know that these basic requirements are unheard of for other large carriers.
Regarding coverage, I'm feeling the pain. I've been a TMobile customer for over 2 years now and their service in NYC is great, but out in Pennsylvania (where I am almost weekly) is terrible to non existent.
On top of coverage being bad, their plans are limited to around 10MB of data roaming per month. Yes, MB. That is only domestic though, if you're international you get unlimited data roaming. I guess that is what happens when you bad-talk other carriers then ask them about letting your customers roam on their networks.
They really did refund my early termination fee with Verizon, and it only took about a month. I was expecting the worst (as is the norm in the world of rebates) and was pleasantly surprised.
The slam dunk for me is the JUMP (Just Upgrade My Phone) program which allows you to upgrade phones much more frequently and easily. Doesn't save much money, but I am tickled knowing that I will get new phones much more frequently now.
I've been a T-Mobile customer since 2004 and I've been really happy with them the whole time. The customer service has always been what kept me there even when I (briefly) lived in poor coverage areas. My feeling is that if you live in a good coverage area and you don't do a ton of travel then theres no good reason not to use T-Mobile.
I checked them out, but their coverage just doesn't exist where I need it. Ended up going with the Verizon Allset plan. Requires that I buy my device up-front, but I get 4G LTE with a gig of base data, the ability to add-on data as-needed, and the ability to tether with no contract, and no activation fees.
Just a reminder: TMobile is also actively chipping away at net neutrality through their 'free' music streaming feature.
That is, they inspect your traffic and don't charge your bandwidth quota for network traffic with TMobile-selected music streaming services (Spotify, Google Play, etc).
They don't DPI your traffic for this feature - if Spotfiy detects you're on .tmodns.net, they will serve you from internal Telekom network caches instead of hitting the wider internet. This is pretty much equivalent to australian ISPs' freezones.
They do DPI for other purposes though, such as ensuring that you don't tether without paying (if you use a desktop browser user agent, it'll count your tethering quota separately -- even if you spoof the UA from your phone's browser), and for "caching" HTTP traffic (you'll see a 'X-Via: Harmony proxy' header on any HTTP traffic, on any port).
They also hijack DNS NXDOMAIN for ad-filled pages, with no usable opt out ("opt out" uses a cookie that uses javascript to serve the page anyway, then hide it with a fake nginx 404)
> even if you spoof the UA from your phone's browser
I don't know about T-Mobile's ways of detection, but AT&T is detecting[0] tethering users by checking the network packets TTL values: If you are tethering then the TTL on their side will be below the expected value of mobile OS's default TTL. There are apps which can hide your tethering usage by altering your device's default TTL. You should still use a mobile browser's UA string, of course.
That is pretty incredible. I knew about ISP's DNS servers that hijacked NXDOMAIN but I've never before heard of MITMing of third party DNS servers! Wow! Have you contacted T-Mobile about it?
I haven't, but that's a good idea. I'm guessing there are semi-legitimate reasons beyond just forcing people to the stupid NXDOMAIN search page. But I agree that it's pretty unpleasant.
I think most of the plans include free tethering now, so I am not too worried about that. I was disappointed to see them redirect to lookup.t-mobile.com though. That is one vote in favor of the people that google everything instead of just typing in a domain name.
At least a couple years ago, when I switched the UA in a different browser to Firefox and forgot to switch it back, it did use up all my tethering data. It just cut me off though, they didn't try charging me oodles of money.
I'm not sure if you know that Spotify is doing that, but Grooveshark is also a music streaming partner and we're not doing any special routing/detection for T-Mobile customers, everything is on T-Mobile's end.
HTTPS doesn't do anything for their DNS servers not returning NXDOMAIN as they ought to. Also, clients can use a VPN all on their own, they can't force all the servers they use to use HTTPS if they don't already.
Charging extra for tethering is total crap—it's just another way the telecoms are trying to erode net neutrality. The fact that they charge for it makes it seem like somehow IP packets from my computer are totally different from IP packets from my phone. If they are worried about computers using more data, then just charge the correct amount for bandwidth (though honestly, in these days of mobile netflix and nice mobile web browers, I highly doubt computers use much more than phones).
Apparently some IP packets are more equal than others.
I don't know. There are some lines I'm willing to cross and feel completely ethical, and bypassing stupid arbitrary net-neutrality rules is one of them.
I get what you're coming from, but personally I'd feel guilty getting something for free when I know I'm supposed to pay for it -- even if I disagree with the way its priced. It's not that far from people who justify pirating Photoshop because Adobe charges too much for it.
No this is like buying Photoshop and Adobe saying you can't let your friend come over and use it without paying for a new license.
I paid for the data. There is no difference if I use the data request comes from my mobile device or if it comes from my laptop connected to my mobile device.
Price discrimination is not a god given right nor is it criminal (usually) to avoid. (I can't think of a case where avoiding price discrimination is criminal, but I'm sure there is)
Google Play Music is specifically not on that list, which makes me terribly sad, Google Play Music All Access is the best deal in streaming right now. Speculation is that it didn't make the list because Google refused to turn off HTTPS on Google Play Music for T-Mobile's packet scanning jobs.
On one hand, it sounds reasonably "fair" for everyone involved. It seems that T-Mo is committed to impartiality (the site repeatedly mentions that all legal music services are eligible). They aren't double-dipping, since it's on top of the metered bandwidth you paid for (as opposed to charging the user for unlimited/unmetered data and then throttling services that don't pay up).
On the other hand, it's terribly opaque. Are they charging the streaming providers? Do the providers need to install dedicated proxies for T-Mo customers? Are they charging everyone the same? Is every service on the same terms? It's quite obvious that they have a cross-promotion deal with Rhapsody, but does Rhapsody get preferential treatment?
It seems that T-Mo are aiming for a compromise in regards to net neutrality. It doesn't seem too bad at this point, but there's always the risk of a slippery slope.
I'd say T-Mo is a great example of why net neutrality is a bad idea. From a purely network engineering point of view, it's efficient to bring those streaming services into the carrier's network instead of sending it over the Internet. Net neutrality prevents the carrier from doing something that makes total technical sense and benefits the customer.
Not really; data passing from the general internet onto the carrier's network (or any wired network) is much much cheaper than that data passing over the limited and contested cellular airwaves. Even if t-mobile has their own cdn servers for the streaming services, the data still has to make the much more expensive hop.
It's really just a marketing technique. Even though music streaming can use a significant amount of data, it's at a safely capped rate. It's probably a lot more effective to market "unlimited music streaming" to the general populace than "500mb more data".
Mobile links are in fact quite often backhaul limited. Especially as you make cell sectors smaller (and in particular with T-Mo, which uses higher frequencies and needs to deploy smaller cells), getting data off the cell sites can become a significant bottleneck: http://www.pcworld.com/article/251838/analyst_mobile_network...
Not yet, but with SD cards now at 512GB capacity, its not out of the realm of possibility to do caching of popular content at-scale across your tower infrastructure.
You're mistaken. Nothing about net neutrality as it is commonly understood prevents the carrier from serving streaming services from their own network. Nothing at all.
It makes it harder for other businesses to enter the same market, as their offerings will not be zero-rated without an agreement with T-Mobile.
Any measure that makes it more difficult for companies to complete will ultimately harm consumers in the long run. So the only people this benefits, ultimately, are the incumbent providers, because it makes their market less competitive. Startups, for one, definitely lose: http://avc.com/2014/01/vc-pitches-in-a-year-or-two/
Please specify one startup that this directly impacts. Which streaming service is left out in the cold, and in what way does this specific situation stifle competition?
Data caps on cellular data plans already exist, so getting uncapped data for specific services does only benefit the consumer.
Your generic "net neutrality is good" arguments don't apply here, where net neutrality has been broken for years. Net neutrality hasn't ever existed on the web, let alone cellular data plans, anyway.
In other T-Mobile security news, their customer website only supports SSL3 and will stop working with Firefox 34 on November 24 (because SSL3 will disabled due to the POODLE attacks). (Their website login is currently broken in Firefox Beta, Aurora, and Nightly release channels.)
Active attacks, involving a device called an “IMSI catcher,” may still be able to eavesdrop on individual calls by manipulating a phone’s security settings directly, without having to crack the encryption.
So, just hardens against passive eavesdropping (and only by upgrading to the latest standard, not by any specially devised method).
Also, I think a tower (real or bogus) can instruct your phone to downgrade to no-encryption, in which case the cipher won't matter.
If they really wanted to be "progressive" they would allow the phone to display a cipher icon for proper encryption with the tower, which was always part of the GSM spec, but was abandoned very early on. I think your SIM card needs to support that as well, IIRC ...
With 2G the network verifies the handset and the handset blindly trusts the network. It's not technically a downgrade, A5/0 null cypher is a perfectly valid choice of the 4 available. Sure it screws you as a user but it's not going to cost the network so that's fine.
Clarification: Notification to null encryption still exists, and iirc then it's actually mandatory. It's just that you can disable the warning by setting a bit on the simcard which it seems nearly every operator in the world does. As it was so unused the majority of even vaguely modern phones don't seem to have bothered writing the code to handle it anyway.
iirc, India _only_ uses A5/0 as it's illegal for them to use crypto [someone please clarify and educate me].
To be fair, it's a lot easier to harden the equipment they own vs the equipment your customers own. I'm not sure such a cipher icon is even possible in iOS without Apple's help. It certainly wouldn't be easy.
It's been a while since I went down this rabbithole, but I think it is required via spec, but only if your SIM card has that feature enabled ... and no carriers anywhere (globally) enable that feature.
So I would be interested to see what happens if you insert a SIM card with security checking turned on, into an iphone...
Germany has great cellular network hackers. If anyone of you would like to know more about this area I'd highly recommend to search for talks by Harald Welte or Karsten Nohl.
For many years I have impression that T-mobile seem to be the most user-friendly network among all of them.
I also enjoy their Simple Talk Network. $40 unlimited talk, text, mms, 3G. Sometimes my friends have hard time on their $120 Sprint or $140 ATT plan to get internet fast in places where SimpleTalk (T-mobile rebrand) works like a thunder!
Good on Tmobile. I had them about 5 years ago and they was pretty good to me. I only switched because I wanted an iPhone and at the time the unlock community didn't come out with a patch. Because of that service I just opened a new line with them for my second phone and so far so good.
A5/3 (Kasumi) is near-on identical to the cyphers used in 3G connections, but you're right, this is the 2G only implementation; so yes, this only affects (applies to) 2G/EDGE/GSM.
I'm absolutely bloody agog that commercial first-world operators have taken until the end of 2014 to actually support this -I think it was ratified into the specification around 2001 if not earlier.
Also, for all you tinfoil wearers out there, you might like the fact that the original specification for A5/3 was altered to make it more hardware friendly. In 2010 it was realized that this actually made it extremely easy [1] to recover the session key (if not in real time) [2].
Integrating support for these algorithms on the device side ends up being a high hurdle. Doing anything at scale is inevitably harder than you expect it to be. If it was a simple change, people would make it.
You're mistaken - 3G/UMTS supports circuit-switched voice calls just fine. It's 4G/LTE that hasn't supported voice calls until very recently when the first networks deployed VoLTE.
Even if A5/3 weren't broken, there are still tower dumps and IMSI catchers, which are a whole lot easier to use than breaking encryption. Yes A5/3 is better than A5/1, but I call bullshit on this whole article.