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Posted by George W. Maschke
- Dec 18, 2014, 04:39 AMTen years ago, I suggested using Skype for "free secure Internet phone calls." I'd like to make clear that I no longer suggest doing that and would advise against it. Documents disclosed last year by NSA whistleblower Edward Snowden reveal that Skype (now owned by Microsoft) has been an NSA PRISM-partner, facilitating the surveillance of its customers, since 6 February 2011.
Recently, Tor developer Jacob Appelbaum, whose opinion I respect, posted on Twitter: "Remember: Never use Skype":
https://twitter.com/ioerror/status/545078471639461889
In a reply, I mentioned to him that whenever possible, I use Jitsi instead, but that at times, when Jitsi won't connect, Skype can be useful (bearing in mind that it is monitored).
He replied to me: "Don't even have Skype installed on your systems. Seriously. Just stop."
I asked for any risk mitigation tips for those who for practical reasons must at times use Skype. Appelbaum replied, "Here is how you mitigate Skype risks: stop using it":
https://twitter.com/georgemaschke/status/545085536646737921
Recently, Tor developer Jacob Appelbaum, whose opinion I respect, posted on Twitter: "Remember: Never use Skype":
https://twitter.com/ioerror/status/545078471639461889
In a reply, I mentioned to him that whenever possible, I use Jitsi instead, but that at times, when Jitsi won't connect, Skype can be useful (bearing in mind that it is monitored).
He replied to me: "Don't even have Skype installed on your systems. Seriously. Just stop."
I asked for any risk mitigation tips for those who for practical reasons must at times use Skype. Appelbaum replied, "Here is how you mitigate Skype risks: stop using it":
https://twitter.com/georgemaschke/status/545085536646737921
Posted by Irishgeek
- May 16, 2006, 09:34 PMSkype is a great application..!!!
Cheapest way for doing long distance calls (Ireland). I have not used the encrypted features yet...will have to give it a try.
Cheapest way for doing long distance calls (Ireland). I have not used the encrypted features yet...will have to give it a try.
Posted by George W. Maschke
- May 16, 2006, 08:34 AMYou can now use Skype to make free calls within the US and Canada through the end of 2006:
http://news.com.com/2100-7352_3-6072256.html
http://news.com.com/2100-7352_3-6072256.html
Posted by Skeptic
- Sep 18, 2005, 05:19 PMQuote from: George W. Maschke on Sep 18, 2005, 07:02 AMWith Skype's acquisition by eBay, it may be less secure. Presumably, as a U.S.-owned company, Skype will become subject to the provisions of the USA Patriot Act, under which the FBI, by issuing a "National Security Letter" (no court order required), may demand customer information from telephone companies, Internet service providers, bookstores, and even public libraries. The recipient of a National Security Letter is prohibited from informing the customer that his information has been provided to the government.
PGP developer Philip Zimmermann, whom the U.S. Government once sought to criminally prosecute for making strong encryption publicly available, is working on a secure VoIP application that is presently called zFone. Unlike Skype, zPhone's source code will be made public for peer review.
The question would be whether or not Skype could build a backdoor into the telephone. I'm not familiar with the protocol, but a backdoor into the software itself would enable tapping.
I don't see any other method by which the telephone call could be tapped, given the level of encryption.
Here's another possible application (one I've not used, myself). It's called SIPfone:
http://www.stud.uni-hannover.de/~twoaday/winpt.html
Posted by George W. Maschke
- Sep 18, 2005, 07:02 AMWith Skype's acquisition by eBay, it may be less secure. Presumably, as a U.S.-owned company, Skype will become subject to the provisions of the USA Patriot Act, under which the FBI, by issuing a "National Security Letter" (no court order required), may demand customer information from telephone companies, Internet service providers, bookstores, and even public libraries. The recipient of a National Security Letter is prohibited from informing the customer that his information has been provided to the government.
PGP developer Philip Zimmermann, whom the U.S. Government once sought to criminally prosecute for making strong encryption publicly available, is working on a secure VoIP application that is presently called zFone. Unlike Skype, zPhone's source code will be made public for peer review.
PGP developer Philip Zimmermann, whom the U.S. Government once sought to criminally prosecute for making strong encryption publicly available, is working on a secure VoIP application that is presently called zFone. Unlike Skype, zPhone's source code will be made public for peer review.
Posted by Skeptic
- Sep 18, 2005, 05:20 AMQuote from: Algol on Sep 18, 2005, 04:20 AMHey Compscigeek,
You can easily prove George wrong...
Just factor his public key and post the two prime numbers that created it.
Course I expect to die of old age first.
Wow. Talk about digging up an old thread
George is right, though. AES has received NSA's seal of approval for the protection of Top Secret data. This isn't a determination made lightly, and if you look at their other criteria and guidelines for dealing with top secret information, it's pretty clear that when it comes to the protection of top secret stuff, NSA doesn't take chances.
It's always possible that someone, somewhere can crack AES. But color me a skeptic that anyone actually can, and yes, that does include the guys at Fort Meade.
At any rate, Skype looks very promising.
Posted by Algol
- Sep 18, 2005, 04:20 AMHey Compscigeek,
You can easily prove George wrong...
Just factor his public key and post the two prime numbers that created it.
Course I expect to die of old age first.
You can easily prove George wrong...
Just factor his public key and post the two prime numbers that created it.
Course I expect to die of old age first.
Posted by dave3582
- Dec 18, 2004, 11:22 PMOh - I forgot to mention - we might also judge an apps credibility by who has released it, and what apps they have released before. Unfortunately, the authors worked on Kaza before, which is good if we are looking at how popular the app might be, but bad if we judge security. They are not Zimmerman.
Posted by dave3582
- Dec 18, 2004, 11:16 PMWhat an interesting discussion I found while I googled for some info on evaluation of Skype's security.
For those searching for some kind of evaluation as I was, better overviews can be found at:
http://www.security-forums.com/forum/viewtopic.php?t=24098&postdays=0&postorder=asc&start=8
(in particular see Justin's reply)
and
http://www.securiteam.com/securityreviews/6K00M2ABFM.html
As for this discussion:
Actually, I think the troll may have made at some good points, whether intentionally or unintentionally, and of course in a very oblique and sometimes offensive manner.
The first issue is whether AES itself is vulnerable. The fact that it appears to be so widely trusted and used, by a variety of different "users", technical, corporate and government, is surely a sign that it works, at least for most purposes. There is no point in evaluating in detail the maths behind it, unless you are willing to put in real effort at becoming proficient (which I for one am not). The fact that it is "open source", and that it has been put forward and scrutinised in academic journals as well as on the internet, without any weaknesses being found, does add to credibility (but I am going off vague and half-remembered second hand rpeorts that no weaknesses have been found). But, by analogy with the Enigma saga (which I think the troll did hint at), it would seem to be possible that there could be a solution to these mathematical encryption schemes, that is held by a few intellectual elites (which all the rest of the mathematicians, even though they are very good, don't know about). Still for practical purposes, it makes sense to assume we have an unbreakable encryption. (The problem of casual snoops and criminals decrypting AES would seem to be allmost impossible, even if at the very highest level the government is playing the double bluff game).
The second, more important issue for Skype specifically, is whether Skype's implementation of AES is robust. Here, we would be able definitely to turn the trolls "point" regarding open source against him. The fact that third parties (such as Justin at the security forum), that we can trust to greater or lesser degrees, cannot look at the implementation because it is poorly documented and not open source, greatly reduces the trust in the product.
But here also, the senior member George has misled slightly, and in some sense has been complicit with the marketing spin of Skype, because he did not point out clearly enough this key weakness of Skype, even though he introduced it as using "strong encryption". Indeed, he only referred to the benefits of open source with regard to AES itself, and missed the opportunity to criticise Skype for not being open source (although he did, albeit briefly, mention the possiblility that their implementation might be inadequate). We only have Skype's word for its efficiency (and they may even have put a deliberate backdoor into the implementation, although points about why they would want to do this and how it would be hard for them to harvest traffic on a large scale are valid). There are a lot of users of Skype, but they seem to be mainly "users" in the consumer sense of the word, and it hasn't been subject to much scrutiny from the corporates or open source community. Given how many users it has got, and given how it hypes the "strong encryption", AES standard, maybe it is time some public spirited techie reverse engineered it and documented the results.
There has been a recent bug fix to fix a buffer overflow in Skype, which in fairness was posted on their site (this does not link to encrytion implementation directly, but if an app allows another to take complete control of your pc, then any enryption is potntially rendered ineffective even if it is a good implementation, aside from all the other problems you will have).
For me, I think I will go ahead and use skype anyway. I don't particularly want random people to be able to hear my conversations, and I am not convinced that Skype will prevent it, but free, reasonable quality phone calls sound too good to ignore. Maybe even a poorish enryption implementation will provide a similar level of security to POTS, becuase it would still require some effort and skill to eavesdrop, unlike with entirely unencrypted traffic.
For those searching for some kind of evaluation as I was, better overviews can be found at:
http://www.security-forums.com/forum/viewtopic.php?t=24098&postdays=0&postorder=asc&start=8
(in particular see Justin's reply)
and
http://www.securiteam.com/securityreviews/6K00M2ABFM.html
As for this discussion:
Actually, I think the troll may have made at some good points, whether intentionally or unintentionally, and of course in a very oblique and sometimes offensive manner.
The first issue is whether AES itself is vulnerable. The fact that it appears to be so widely trusted and used, by a variety of different "users", technical, corporate and government, is surely a sign that it works, at least for most purposes. There is no point in evaluating in detail the maths behind it, unless you are willing to put in real effort at becoming proficient (which I for one am not). The fact that it is "open source", and that it has been put forward and scrutinised in academic journals as well as on the internet, without any weaknesses being found, does add to credibility (but I am going off vague and half-remembered second hand rpeorts that no weaknesses have been found). But, by analogy with the Enigma saga (which I think the troll did hint at), it would seem to be possible that there could be a solution to these mathematical encryption schemes, that is held by a few intellectual elites (which all the rest of the mathematicians, even though they are very good, don't know about). Still for practical purposes, it makes sense to assume we have an unbreakable encryption. (The problem of casual snoops and criminals decrypting AES would seem to be allmost impossible, even if at the very highest level the government is playing the double bluff game).
The second, more important issue for Skype specifically, is whether Skype's implementation of AES is robust. Here, we would be able definitely to turn the trolls "point" regarding open source against him. The fact that third parties (such as Justin at the security forum), that we can trust to greater or lesser degrees, cannot look at the implementation because it is poorly documented and not open source, greatly reduces the trust in the product.
But here also, the senior member George has misled slightly, and in some sense has been complicit with the marketing spin of Skype, because he did not point out clearly enough this key weakness of Skype, even though he introduced it as using "strong encryption". Indeed, he only referred to the benefits of open source with regard to AES itself, and missed the opportunity to criticise Skype for not being open source (although he did, albeit briefly, mention the possiblility that their implementation might be inadequate). We only have Skype's word for its efficiency (and they may even have put a deliberate backdoor into the implementation, although points about why they would want to do this and how it would be hard for them to harvest traffic on a large scale are valid). There are a lot of users of Skype, but they seem to be mainly "users" in the consumer sense of the word, and it hasn't been subject to much scrutiny from the corporates or open source community. Given how many users it has got, and given how it hypes the "strong encryption", AES standard, maybe it is time some public spirited techie reverse engineered it and documented the results.
There has been a recent bug fix to fix a buffer overflow in Skype, which in fairness was posted on their site (this does not link to encrytion implementation directly, but if an app allows another to take complete control of your pc, then any enryption is potntially rendered ineffective even if it is a good implementation, aside from all the other problems you will have).
For me, I think I will go ahead and use skype anyway. I don't particularly want random people to be able to hear my conversations, and I am not convinced that Skype will prevent it, but free, reasonable quality phone calls sound too good to ignore. Maybe even a poorish enryption implementation will provide a similar level of security to POTS, becuase it would still require some effort and skill to eavesdrop, unlike with entirely unencrypted traffic.
Posted by Jeffery
- Nov 11, 2004, 09:14 AMCompscigeek-
Can you document the good points you supposedly have made in this thread? I've read and re-read these posts and can't really see the good points to which you refer.
To summarize:
Skype can't possibly be secure because two guys couldn't possibly implement industry standard encryption that would defeat the full might and power of the billions of dollars of US government computer technology? And if the government had the capability to easily crack encryption, they couldn't tell us about it because they want to keep it secret and keep us thinking they can't crack encryption?
Is this the just of the good points to which you claim to have made? How does George's dispute of some of your points and asking you for evidence hurt his credibility?
I would agree that the fact packets seem to be encrypted in the first place would draw more attention to those packets. But big deal. The fact that skype has excellent audio and works through most firewalls is reason enough to use it. The fact that your communications would be hidden in billions of other minutes of skype audio, and disperssed through multiple P2P relays would make intercepting it and cracking it difficult even for the most expensive of mythical government systems.
Can you document the good points you supposedly have made in this thread? I've read and re-read these posts and can't really see the good points to which you refer.
To summarize:
Skype can't possibly be secure because two guys couldn't possibly implement industry standard encryption that would defeat the full might and power of the billions of dollars of US government computer technology? And if the government had the capability to easily crack encryption, they couldn't tell us about it because they want to keep it secret and keep us thinking they can't crack encryption?
Is this the just of the good points to which you claim to have made? How does George's dispute of some of your points and asking you for evidence hurt his credibility?
I would agree that the fact packets seem to be encrypted in the first place would draw more attention to those packets. But big deal. The fact that skype has excellent audio and works through most firewalls is reason enough to use it. The fact that your communications would be hidden in billions of other minutes of skype audio, and disperssed through multiple P2P relays would make intercepting it and cracking it difficult even for the most expensive of mythical government systems.
Posted by compscigeek
- Nov 11, 2004, 05:35 AMyou can't accept the fact that ive made some good points, and maybe im eating your credibility to sell your anal puckering techniques to pothead-would be government employees. hey, "ive got some jargon that no one will understand and make me sound credible". common sense and good logic isn't enough. great marketing with the cnss policy. skype, this wonderful free program that you love so dearly, is as good as the best technology our country has to provide for our national security. tools...
Posted by George W. Maschke
- Nov 11, 2004, 04:36 AMcompscigeek,
So the CNSS fact sheet on AES -- which flatly contradicts one of your previous arguments -- is now part of a grand deception by the U.S. Government? Yeah, sure.
I think that by now it is more than clear that you have been talking through your hat from the very beginning. In view of your continued failure to back up your assertions, your resort to ad hominem attacks, and your unwillingness acknowledge any error, even when it is so clearly pointed out for all to see, I see no point in discussing this matter with you any further.
So the CNSS fact sheet on AES -- which flatly contradicts one of your previous arguments -- is now part of a grand deception by the U.S. Government? Yeah, sure.
I think that by now it is more than clear that you have been talking through your hat from the very beginning. In view of your continued failure to back up your assertions, your resort to ad hominem attacks, and your unwillingness acknowledge any error, even when it is so clearly pointed out for all to see, I see no point in discussing this matter with you any further.
Posted by compscigeek
- Nov 10, 2004, 10:40 PMif i had that evidence i probably wouldn't be able to give it to you, because it wouldn't be public knowledge...and who cares what that sheet said, they can print anything they want to keep our security safe. anything that the general public knows in the states, is known in the world. wouldn't you rather let everyone think you have a pea shooter, when you really have a cannon?
Posted by George W. Maschke
- Nov 10, 2004, 11:32 AMQuote from: compscigeek on Nov 10, 2004, 11:08 AMi hope they paid you to say that, because that was excessive. it's naive to think that the government's capabilities with computing stretch as fas as you and i would like to think.
What are you talking about?
Quotewhy would the government make it public that their top secret information is 256 bit encrypted....sounds like fairy dust to me. it would be like declassifying the paint used on a stealth fighter.
See, CNSS Policy No. 15, Fact Sheet No. 1 ("National Policy on the Use of the Advanced Encryption Standard (AES) to Protect National Security Systems and National Security Information"):
http://www.nstissc.gov/Assets/pdf/fact%20sheet.pdf
Quotei wouldn't expect them to decrypt your calls unless they had good reason to. i certainly wouldn't expect them to listen in on everyone. it doesn't take much though, you seem to be, after all, a big part of antipolygraph.org..which is working against the gov.'s intentions in some ways isn't it?
Again, you have offered no evidence whatsoever that would suggest that the U.S. Government (or anyone else) has any ability to crack 256-bit AES in general or Skype's implementation of it in particular.
Posted by compscigeek
- Nov 10, 2004, 11:08 AMi hope they paid you to say that, because that was excessive. it's naive to think that the government's capabilities with computing stretch as fas as you and i would like to think. why would the government make it public that their top secret information is 256 bit encrypted....sounds like fairy dust to me. it would be like declassifying the paint used on a stealth fighter. i wouldn't expect them to decrypt your calls unless they had good reason to. i certainly wouldn't expect them to listen in on everyone. it doesn't take much though, you seem to be, after all, a big part of antipolygraph.org..which is working against the gov.'s intentions in some ways isn't it?