Friday, 4 May 2012

Microsoft changes skype supernodes architecture to support wiretapping

Two months ago, Skype replaces user-hosted P2P supernodes with Linux grsec boxes hosted by Microsoft, but for what?

I found some brilliant and valuable comment about this:
I think wiretapping is one of the big reasons for the rearchitecture. Skype officially claimed they could not comply with wiretapping requests because of the P2P network as late as 2008 (, and Microsoft was already working on wiretapping VoIP in 2009 (
via Hacker News


So, think twice.

P.S. M$ talking, that "supernodes don't transit voice traffic" - this is bullshit. They do. In case, where you both behind NAT or in case of authority curiosity.

P.S2. Especially, for Kostya Kortchinsky at post.
Relay nodes take care of those if you can't communicate directly with the other end. There is a mutual exclusivity in that a node can't be a relay and a supernode at the same time.
Can he prove it? No. But, I can. This code, which I wrote in past, will allow for your traffic to flow via supernode(and also relay node): skyrel.c skypush.c

How to deal with AES keys? Not big problem, if you have Skype RSA CA(certificate of authority) private key, which skype/microsoft obviously have.

So, forget about security and anonymity in microsoft-skype.


  1. Aren't Skype supernodes more like DNS? Just telling the two parties how to connect with each other and then getting out of the middle?

    1. Supernodes also have the ability to relay the VoIP traffic if the callers cannot form a P2p connection. More info here
      It would be a small change to the supernode logic to enable relaying of calls for wiretap requests.

    2. I don't understand. Isn't end-to-end encryption something that has been solved since the eighties?

      I realize that Skype is in some sense special - obviously when there is silence on both ends, you should not be flooding the load-sensitive relay node with padded packets - so, no padding means that highly complex voice packets will encrypt to bigger packets than low-complexity silence, and by seeing how different morphemes encrypt you can kind of make some guesses about the conversation. Fine. There was research about this.

      But does skype not even try to use end to end encryption, however breakable?

  2. I can't wait to be able to encrypt the speech on the client side before sending it over the network. =)

  3. Isn't there some encryption involved?

    1. Yes but:
      1) the encryption algorithms are secret, so we don't know how good they are and
      2) Skype(microsoft) have the keys

    2. Sounds like we urgently need a secure and opensource VOIP system that we can trust.

    3. jitsi seems like the best alternative right now.

    4. or boophone

  4. Others have argued that the real value of this is the improved user experience (and control over the user experience). That's almost certainly true. But more importantly, mining data from Skype would be of negative value to MS.

    Trying to gather any information that's utterly generic and innocuous would cause a massive PR scandal that would probably destroy Skype's credibility for ever, and possibly taint many other of Microsoft's online services as well. What data worth from wiretapping could possibly be worth $8+ billion?

    The only way it could possibly make sense is if they were certain of never getting caught. And that's a tall order in these days. All it takes is one lawsuit against MS where the legal discovery process can touch documents and communications pertaining to Skype.

    1. It's one thing to wiretap with a court order.

      It's very different to mine data for evidence of criminal intent and send that to the authorities on your own volition (like Facebook does). That's generally *illegal* under the Stored Communications Act and I hope Facebook gets their pants sued off.

      The thing is that VOIP is not so easy to mine data from. You'd have to text to speech and then mine data from it. So it's a lot of work for a very negative payoff. I can't believe that Microsoft would be that stupid.

      But it is a good reminder to be careful about these new technologies and the capacities for abuse.

    2. Some people might say...

      (1) - Why would they tell anyone, they never have before.
      - go find a Catalogue of law suits already take out against BT, Virgin, Talktalk, MS, Google etc etc
      (It won't take you long)
      - Sadly, most people don't know how to VOTE, and just hope someone else will keep their rights safe.
      THEY WON'T - You have to do it, Yourself.

      (2) - Bad publicity didn't stop SKY in the UK
      - and Rupert Murdoch STILL isn't in jail for the CAPITAL Offense of Espionage. (the one the US is trying to extradite and torture Julian Assange for)

      (3) - Citizens have a RIGHT to Privacy (not to have that privacy infringed at-will by those with Wealth)

      (4) - Civil Servants (politicians) have a DUTY to Defend YOUR Rights. THAT'S WHAT YOU PAY THEM FOR.

      (5) - LAW prevents 'stalking/espionage' by anyone but the Police - Then ONLY with Just Cause & a Warrant. - unless Zuckerburg succeeds in pushing CISPA thru.

      ^^ THIS is how Democratic Freedoms works, unless you'd prefer the US alternative. Capitalist Mass-Control.

      ^^ Remove these & ANY company, ANY government can buy, sift, trace, read and LISTEN to every word YOU say.
      - Automatically in the Very near future.
      Both Online and IN PERSON, by any means they choose.

      If it sounds sinister, IT IS - bad enough that 'the rich' are given Monumental privileged in Court (not Law). Imagine if they could Legally Persecute Anyone, with anything they wouldn't want revealed. If someone who didn't like you could Buy your 'Profile' and use it against you... (and read what the IOC-Olympics - have already done this year to protestors)

      People might also say that... :oD

      COKE ignore their daily 'massive PR scandal' as they happily murder and pollute by sub-contract in any 2nd world country & advertise themselves into profit.
      M$/Skype don't insist their suppliers protect Workers Rights, care where they buy materials or which arms-dealers they do business with.
      Why would they be any different?

      If they want Solid P2P systems, INCREASE the Network Capacity & Number of Peers - Peeriod ;oJ

      Adobe run SD TV on this principal thru FMES.
      ^^ This also saves them a Fortune as the End User (you) does much of the encoding, relaying etc...

      M$ want you to ignore it, listen to the debate & hope it will be ok. They CAN build secure, communal, comms - but they DON'T. At HUGE additional cost to themselves. << And your not asking WHY?

      Zuckerberg (Facebook) already buys server data on YOU and Your Friends every day. Where you Shop, Your emails, Your friends email Address's - and sells them (legally) to anyone who wants them.
      More information than has Even been held by Any intelligence agency Ever - in the hands of an self-serving, Industrial Egoist. Why would you trust him?

      I Don't Like being Stalked.
      If a person lurked at your house, noting where you went, who you spoke to and when. You'd take out a restraining order on them. As well you should...

      BUT WHAT CAN I DO? - You say...

      If every American spent $27 less per YEAR on MS kit - they would be loosing $8000,000,000 ($8bn) - and that's just the US. They are Global.

      You are INCREDIBLY Rich and Powerful.
      It might not feel like it, but every dollar you hold is a Vote. A Choice. So CHOOZE
      Vote with your Dollar, Don't buy from scum.
      Don't use Scum-ware (like Skype) there a Oodles of websites that won't stalk you, at very least they aren't big enough to Steal Your Rights, MS - ARE.

      So don't build Bills empire or believe a single word of the 'explanation'

      Some people might say... he's a c**nt xxJ

  5. Agencies reaction:

    FBI Wants Backdoors in Facebook, Skype and Instant Messaging
    Wired News - 2 hours ago

    FBI: We need wiretap-ready Web sites -- now
    CNET - 4 hours ago

  6. session key agreement was explained in public security review paper, dated october 2005:

    1. Supernode can easily act like a remote buddy. Because with RSA CA private key you can generate valid RSA certs-credentials of any user. So its standard MitM-attack.

    2. ---
      3.4 Attacks on the Skype Key Agreement Protocol

      3.4.1 Man-in-the-Middle (MITM) Attacks

      A last scenario requires defeat of the security mechanisms at the Skype Central
      Server. As I pointed out above, digital certificates created by the certificate
      authority are the basis for identity in Skype.

      Microsoft now have:
      1) Traffic
      2) CA key

      Job done.

  7. I'm not sure but there are other places you can try to host decrypted binaries and related code. GitHub is in the US and they always listen to DMCA takedown notices without question as a result.

    Gitorious is one example that does not and they are not in the US. When the PS3 hacking started happening, it was clear GitHub would not be the place to host any code. Gitourious became one of the places instead.

  8. Gitorious removed ps3 hacks too (for DMCA)

  9. seems to me it was just a matter of time when this had to happen, anyway time has come for an healthy open-source, secure, replacement for skype

  10. what's wrong with XMPP/jabber? it supports voice, video and encryption. doesn't it?

    1. Nothing's wrong with XMPP/Jabber. Unfortunately, (almost) no one uses it.
      1. It's not user friendly enough yet. Not a problem to configure for me, but your average grandma probably wouldn't be able to set it up.
      2. It's not widespread. I'm pretty sure 89% of the society never even came across the name. I guess you could maybe count Jabber/XMPP users is tens of thousands. Constrast with 280 million Facebook accounts. It makes no sense to speak to people in Navajo in the middle of China, just as it doesn't make sense to speak XMPP/Jabber to Skype/[nation's favourite IM client] people.
      3. Network provider-specific free communication. Never underestimate that. I use Skype to call home whenever I'm outside because our mobile network lets us use Skype calls and IM completely free. You could even get a pre-paid SIM and NEVER have to top up and Skype-call and Skype-IM 24/7.

      I'm NOT comfortable with using Skype (mainly because it's closed-source so I don't trust it security-wise) but if I/my family didn't, we wouldn't be able to call each other AND the people abroad at such an affordable price. It's quite good value despite its flaws. Life's full of compromises you have to make and this is just one of them, I guess. At least until everyone and their grandma switch to XMPP and the network providers will start doing ONLY 3G-data protocol-neutral contracts. I would be happy if XMPP/Jabber overtook Skype, but it might take some time.

  11. Do you have the decompiled MAC OS X version as well?

  12. Google+ Hangouts to the rescue.

  13. So the FBI is pushing for wiretaps in all such communications. They tried to mandate backdoors in email too a while back.

    I think the big thing we need are decentralized public key encryption infrastructure approaches, perhaps with an ability to publish a key via DNS or the like. Then we need products which do end-to-end encryption over it.

    The FBI has routinely lost every major encryption battle they have started since about 1990 though.

    The larger issue though is the NSA.....

  14. +1 for osx version. i wanna play

  15. fuck me, you geeks talk some utter shite

  16. Use Skype sucks anyway.

  17. Good post. Someone needs to build an onion flavored VOIP solution. Open source of course...

  18. > Supernodes don't handle traffic

    No, hole punching method will work for all combinations of firewall at each end of the intended communications channel. If connecting the clients directly in either direction after the initial negotiation fails then Skype (and tools like it) will instead send the data via a 3rd host (which sits in the middle and acts as a bridge between the two TCP streams).
    If they get a wiretap order and your client can normally achieve a direct connection with a particular user, they could just emulate connection failure and the clients would revert to using the proxy without informing the user (after all, they are designed to do that for the sake of resilience of the user experience). You can probably see where the traffic is going, the client may even tell you without you having to dig far, but you won't know if you are going via the middle-man server(s) because of a general network issue that is stopping a direct connection being possible or if it is because of a wire-tap.


  19. I think these 2 older articles support that conclusion as well:

    All of the sudden the outrageous $8.5 billion price Microsoft paid for Skype (and twice as much as any other competing bid) starts to make sense.

  20. The European Union is considering changing the law so VoIP conversations using services such as Skype can be tapped during law enforcement investigations.

  21. "Microsoft has replaced P2P Skype supernodes with thousands of Linux boxes"

    > So the question would be, Is it worth rewriting a ton of working code just so we can say it runs on our platform.

    But no code needed to be rewritten. Skype supernodes were working on Windows before (on Windows machines in the P2P network.) Microsoft effectively stopped supporting Windows!

  22. Just thinking out loud, but wouldn't it be possible to build a simple skype-addon that would look at your network traffic and be able to tell if your voice conversations were going through a supernode and not p2p.
    This way you would get a quick indicator of whether or not you were likely being monitored.

  23. Explaining Supernodes

  24. The National Security Agency put out an RFP for Skype decrypting/intercepting awhile back and this was the first thing that popped back into my mind when Microsoft bought Skype. Then, when M announced they were replacing the supernodes, it only re-confirmed what was going on, in my mind.

  25. I think it is more likely because they want to build a social network for collaboration around Office 365, Yammer and Skype, and maybe, be able to give some uptime/quality guarantees to customers (things would not necessarily be better, but more under control of Microsoft)
    If you have a distributed system but want to wiretap some calls, I think it would be easier to have some back door for instructing clients "whenever you make a call/get a call from one of these numbers, CC us".

  26. > The evidence on this one is rather thin. It takes a speculation in a comment on HN about what Microsoft could be doing - without any proof that they are actually doing it, adds some code that proves something Microsoft claims they do not do could be done if they wanted to do it - and the conclusion is Microsoft definitely has sold everybody to the Man. I think a jump from "they could be doing it" to "they did it" requires more proof than that.

    This is for anyone who was assuming that Skype wasn't wire-tappable. But then again, I don't know why anyone would assume that in the first place.

  27. > This means new opportunities in the VoIP market. Thank you Microsoft

    > In the short term, I'm hoping Google Hangouts will be a viable alternative for both normal users and enterprise users.
    In the long term, I hope the WebRTC protocol will disrupt both of them.

    > Why are Google Hangouts a viable alternative for people who care about privacy? (Ostensibly the point of this article.)

    > I agree. Distributed and P2P with encryption is the only way to guarantee privacy.

    > first, make yourself familiar with WebRTC. it will require server side signaling. demo by google: sending srtp session keys over that signaling server sounds interesting

  28. > Did we really think we could trust Microsoft with such an acquisition?

    > You used to trust a shady Europe-based private corporation; now you have to trust a shady US-based private corporation. Regardless of their specific track records, there is nothing intrinsically different between the two.

    > Except executive management and leadership

  29. > Any privacy we could had using Skype was dead the same day MSFT bought them. It was just a matter of time to make it official.


  31. > Its called a hostile takeover. MS has a long history of buying tech companies out and then deep-sixing the tech forever.


  33. Why do you think the FEDS dropped the monopoly lawsuit(s) back when against MS and why do you think the FEDS were involved in the last few distributions of their OS. their are built in back doors to all MS OS's now. MS and the FEDS are in bed together. Same goes for Google and Apple and the rest of them.
    Long Live Linux.

  34. Microsoft Patents VoIP and Skype Wiretapping

  35. legal intercept microsoft

  36. Big brother Microsoft listens in to your Skype IMs

    No, Microsoft and Skype are not playing Big Brother

    What Does Skype's Architecture Do

    Skype denies police surveillance policy change

  37. Is Skype snooping on your conversations?

  38. Why I Don't Care If Microsoft Can Listen In On My Skype Calls


  40. they don't want supernodes because that gives independency to the net, to the users. They want to eface skype so first, they remove that supernodes capacity and then, they will finally remove the servers. It's a big bussines to make skype to work no more and so they did pact to make it this way. Microsoft was paid to do the job. I'ts very important to do reverse engineering the protocol and to spread it with the servers protocol all in the old version. To de world. To the people.

  41. У российских спецслужб появилась возможность отслеживать разговоры в Skype, рассказали«Ведомостям» несколько участников рынка информационной безопасности. Гендиректор Group-IB Илья Сачков говорит, что спецслужбы «уже пару лет»
    могут не только прослушивать, но и определять местоположение пользователя Skype.«Именно поэтому сотрудникам нашей компании, например, запрещено общаться на рабочие темы в Skype», — говорит Сачков.

    После того как Microsoft в мае 2011 г. приобрела Skype, она снабдила клиента Skype технологией законного прослушивания, рассказывает исполнительный директор Peak Systems Максим Эмм. Теперь любого абонента можно переключить на специальный режим, при котором ключи шифрования, которые раньше генерировались на телефоне или компьютере абонента, будут генерироваться на сервере.

    Получив доступ к серверу, можно прослушать разговор или прочитать переписку. Microsoft предоставляет возможность пользоваться этой технологией спецслужбам по всему миру, в том числе и российским, объясняет эксперт.

    По словам двух специалистов по информационной безопасности, доступ к переписке и разговорам в Skype российские спецслужбы не всегда получают по решению суда — иногда это происходит «просто по запросу». Считать, что прослушивание Skype представляет собой для российских правоохранительных органов непреодолимую проблему, нельзя, подтверждает сотрудник МВД. Официальные представители МВД и ФСБ отказались от комментариев.

    Также поступили и представители Microsoft. Раньше глава российской Microsoft Николай Прянишников говорил, что Microsoft может раскрыть исходный код Skype Федеральной службе безопасности. Сам по себе код не позволил бы спецслужбам прослушивать разговоры, но при помощи его спецслужбы могли бы легче найти способ «дешифровки» информации.

    Два российских предпринимателя, перебравшихся в Лондон подальше от российских правоохранительных органов, рассказали, что им известно о возможностях прослушивания Skype, поэтому они пользуются сервисом«с большой осторожностью». Их сосед — основатель «Евросети» Евгений Чичваркин — поступает так же. А вот в 2009 г. Skype обеспечивал конфиденциальность, считает Чичваркин: он пользовался им в момент обысков, которые происходили в

    На этой неделе стало известно, что в китайской версии Skype есть специальный механизм для отслеживания действий абонента. Ученый Джеффри Нокел из Университета Нью-Мексико установил, что в китайский дистрибутив Skype встроен кейлоггер — специальная программа, фиксирующая действия пользователя на клавиатуре. Она проверяет тексты на содержание в них нежелательных слов и пересылает собранные логи«куда следует». Нокел составил даже перечень нежелательных слов: Тяньаньмэнь(площадь, где в 1989 г. были подавлены протестные акции), Human Rights Watch,«Репортеры без границ», BBC News и др.

  42. What do you think about ?