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Google's Obfuscated TCP
Posted by
kdawson
on Tue Oct 07, 2008 07:53 PM
from the shake-hands-when-you-say-that dept.
from the shake-hands-when-you-say-that dept.
agl42 writes "Obfuscated TCP attempts to provide a cheap opportunistic encryption scheme for HTTP. Though SSL has been around for years, most sites still don't use it by default. By providing a less secure, but computationally and administratively cheaper, method of encryption, we might be able to increase the depressingly small fraction of encrypted traffic on the Internet. There's an introduction video explaining it."
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Firefox isn't helping (Score:4, Insightful)
Firefox isn't helping the lack of SSL on the web by throwing a ridiculous warning when using self signed certs. Browsers should treat self signed certs as 'unsigned with the added bonus that communications can't be eavesdropped' instead of freaking out that you might not know who you are talking too.
self signed certs aren't appropriate for processing credit cards... but not every site that has forms needs that... and simply removing eavesdroppers would be a step in the right direction.
Re:Firefox isn't helping (Score:5, Interesting)
"simply removing eavesdroppers would be a step in the right direction."
Yes. Whereas self-signed certs let the eavesdropper send you a certificate which makes you think your connection is secure when in reality they're listening to everything you send.
Parent
Re:Firefox isn't helping (Score:5, Informative)
Per definition, then you're more than an eavesdropper. Then you're actively intercepting and rewriting the connection, which is a lot more complicated to do in volume plus detectable by comparing fingerprints. Whereas just copying the stream for the NSA is trivial and without detection possibility, but hey pick no security because the other is imperfect.
Parent
Re:Firefox isn't helping (Score:5, Interesting)
Or distinguish between "authenticated" and "encrypted"?
Or finally admit that maybe there are more shades of grey than "secure" and "insecure" when it comes to send and fetching data over the Internet?
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Re:Firefox isn't helping (Score:5, Interesting)
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Re:Firefox isn't helping (Score:5, Insightful)
The point being that this is the actual security hierarchy, from best to worst:
Whereas most web browsers make it appear like this:
Any browser that warns you about self-signed certs should make at least as much of a fuss about using plain HTTP, but they don't. Firefox takes it to ridiculous extremes but they're all faulty in this respect.
And really, if browsers would save the self-signed cert and then alert me if it changes the way SSH does, then the result will be very good, nearly as good as a regular cert (and potentially even better, since there's no potential for compromising the trusted certificate authority).
Parent
Re:Firefox isn't helping (Score:5, Insightful)
So stop displaying the lock symbol! Nothing requires you to treat "real" SSL and self-signed SSL identically. It should be obvious that the current standard approach of making them look exactly the same except for a scary warning that appears the first time you hit a self-signed site is broken. But nobody cares about doing better because it's the "standard".
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Re:Firefox isn't helping (Score:5, Insightful)
aka: "Whereas having a keyed lock on your door lets a thief pick the lock and steal everything inside."
Therefore we should make it less convenient to put locks on doors.
Parent
Re:Firefox isn't helping (Score:5, Insightful)
SSL without a trusted certificate provides NO additional security over communicating in the clear. AT ALL.
Bzzzt, wrong, thanks for playing.
Yes, the man in the middle attack is very real. However, it takes a great deal more work to set up than a simple sniffer, because you have to either capture/block/proxy/rewrite packets so that each side thinks it's speaking with the other, or spoof the DNS somehow.
On the other hand, a simple network sniffer can capture almost everything send in the clear, no special network tricks needed.
Authentication requires encryption. Encryption does not require authentication, but should then be considered somewhere between truly secure and just wide open. Call it a nice-to-have that prevents casual sniffers from picking up passwords to your home server, reading your webmail, and the like.
Your assertion assumes that there are no casual crackers/script kiddies out there who won't immediately escalate to some invasive and rather difficult MITM attack, or that sniffing is not a real danger. I'd argue that 90% of the insidious activity comes from just sniffing cleartext off the wire, and that more sophisticated attacks are significantly rarer. Encrypting the over the wire traffic is a way of mitigating a significant portion of that risk.
Parent
Re: (Score:3, Informative)
Indeed. You have to press one additional key to forge SSL connections in most "off-the-shelf" sniffers. I recall doing this with ettercap many years ago.
Re: (Score:3, Insightful)
EXACTLY! With a self-signed certificate, there's no indication that a man in the middle attack is taking place.
SSL without a trusted certificate provides NO additional security over communicating in the clear. AT ALL.
Self-signed != untrusted, and CA-signed may not always = trusted. Why do people always seem to just assume that CA-signed/self-signed are equivalent to trusted/untrusted?
There are ways to verify certs other than having a site- (or attacker-) chosen CA sign them. For example, the Perspectives [cmu.edu] firefox extension relies on "you can't fool all of the people all of the time" rather than the "you can't fool any of these people ever" that the CA system relies on. And it works regardless of whether a cert is self-si
Re:Firefox isn't helping (Score:5, Interesting)
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Re:Firefox isn't helping (Score:5, Interesting)
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Re:Firefox isn't helping (Score:5, Insightful)
I dunno. I just click "Okay" until the windows go away and I can see the website.
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Re:Firefox isn't helping (Score:5, Insightful)
Most users are too dumb to check for SSL, good luck getting them to discern insecure, 'insecure but can't be eavesdropped', and secure.
Fair enough. So don't put the secure green lock up for self signed SSL. Put up a totally different icon in some neutral color like blue. If they click on it it says, the connection is encrypted and can't be eavesdropped but there is no gaurantee you are talking to who you think you are.
Hell, most users would be shocked to find out you can eavesdrop on their traffic in the first place.
Good point! Maybe firefox 3 should pop up a huge error screen every time you try to connect to a site with plain http. It could say something like:
The server you are connecting to is insecure. Maybe there is a configuration error on the server. Or maybe someone is trying to impersonate it. Oh, and by the way, not only that, but any communication with them maybe trivially intercepted by any 3rd party...
Are you sure you want to communicate with them?
Then it could have friendly buttons like:
"Hell no get me out of here." or "Ok, I don't mind getting pnwed!"
Parent
surveillance (Score:5, Insightful)
The video starts out saying that increased encryption is needed thanks in part to warrantless government surveillance. It then goes on to describe a system that assumes no MITM attacks can exist. The fact is, however, that governments are entirely capable of performing MITM attacks, as can telecommunications companies; and if it becomes popular we may see more techniques that allow individuals to perform MITM attacks. While this algorithm has significant merit, care needs to be taken to avoid a false sense of security.
Re: (Score:3, Insightful)
Which is why the video states that SSL/TLS should be the only user visible transport security and their third goal is to have no visual indications and no alternative URL schemes.
Re:surveillance (Score:5, Insightful)
It does not "assume no MITM attacks can exist". It deliberately does not protect against them. This is not the same thing, as one is a position of ignorance whereas the other is an intentional choice not to defend against that threat.
In practical terms, MITM is considerably harder than simply listening in. Wide-scale surveillance such as what caused the big recent flap with FISA and the NSA simply can't perform MITM attacks. Protecting against pure eavesdropping while remaining open to MITM attacks is useful, it's just not a 100% solution. As long as it doesn't sell itself as one (and I see no indication that it is) then there's absolutely no problem with that.
Parent
Re: (Score:3, Interesting)
That's not really the point though. It raises the bar of work needed to implement these snooping systems and can prevent ISPs from placing their own adverts into webpages.
NOT GOOGLE (Score:5, Informative)
This is not GOOGLE's Obfuscated TCP, this is a small one-man project HOSTED on Google Code.
That guy's gonna get tons of traffic for what's maybe a good idea but not endorsed or supported by Google.
Re:NOT GOOGLE (Score:5, Informative)
He's a Google employee. [blogspot.com].
(Standard 20% time disclaimer etc)
Parent
Less secure than 128bit SSL? Why? (Score:4, Insightful)
By providing a less secure, but computationally and administratively cheaper, method of encryption, we might be able to increase the depressingly small fraction of encrypted traffic on the Internet.
If the encryption is computationally cheaper, then the decryption is computationally cheaper. I'd rather people know that what they're sending over the 'net can be sniffed than have them think that because example.com uses Rot13 encryption their traffic is private.
Trusts DNS instead of CA signature (Score:5, Insightful)
So, basically we have the same concept as SSL, except instead of trusting the CA signature on the certificate, we trust DNS.
Forging a CA signature on a certificate would be a BIG DEAL.
Forging a DNS entry, especially with ISP cooperation(read government snooping), is DEAD SIMPLE.
So we replace real security with, well, a CPU hog that's only a smidge better than running everything in the clear. It only keeps out the MOST casual, lazy, and uninterested snooper.
Re: (Score:3, Insightful)
Forging a CA signature on a certificate would be a BIG DEAL.
Forging a DNS entry, especially with ISP cooperation(read government snooping), is DEAD SIMPLE.
True, if it required you to forge a real CA's signature. The whole point of self-signed certs is that there is no CA - you're not impersonating being anyone other than the website and it has zero effect on anything else. I can make such a certificate up in a terminal in the time it takes me to type it. I don't know if it would be a bigger deal legally, but technically it is equally dead simple. And if it was legally a big deal I'm sure they can get some retroactive immunity for it.
They could have done better (Score:5, Interesting)
I read the technical details [google.com] and they talk about an advert being encoded in the CNAME, to distribute a curve25519 key and a port number. But they could have done much simpler using technology that already exists: encode the 160-bit SHA1 fingerprint of an X.509 certificate and a port number in the CNAME (only 32 chars needed in base32). Then connect to this port using HTTPS and simply verify that the certificate matches the fingerprint ! Advantages:
Re:They could have done better (Score:4, Insightful)
Parent
what's wrong with ipsec? (Score:4, Interesting)
Seriously, not trying to troll, but wasn't this problem solved more completely by IPSEC back in 2000? Why hasn't IPSEC been adopted more? Why should this solution fare any better?
Re:what's wrong with ipsec? (Score:5, Informative)
IPSec prevents its own widespread adoption in two ways:
1) IPSec is very much about authenticating who you are talking to on the other end. If two nodes connect for the first time, with no previous knowledge, they have no way to authenticate the other is who they say they are. This is a failure to IPSec - you'll get no SAs, and most implementations will drop traffic that would've required that SA.
2) The classic key exchange issue:
a) You can authenticate a session using certs, but now you have the same problems as signed SSL certs, except that every host participating needs to have one and know about all the other nodes' CAs.
b) You can instead opt to use a pre-shared key, but now you have to pre-share the key. This is fine when you are looking to secure specific traffic to a specific node.
For uses that aren't affected by these downsides, IPSec is a hugely popular technology. VPNs between a branch and central office as well as remote access for roaming users are very popular. Of course in these cases you can very meaningfully authenticate the other end and the key exchange isn't a problem.
Parent
Re:what's wrong with ipsec? (Score:5, Funny)
Ever set up IPSEC? Yeah, that's why.
Parent
Any commonplace encryption is helpful (Score:4, Insightful)
we might be able to increase the depressingly small fraction of encrypted traffic on the Internet.
I agree that this would indeed be a good thing for several reasons. An encrypted message in a medium where most everything is plaintext may attract the attention of attackers or, worse, be seen as "suspicious" by a government. (Certainly the U.S. and the PATRIOT Act spring to mind, but let's not forget the truly oppressive governments such as China's and any number of third-world dictatorships.) If online privacy via encryption comes to be a right that everyone gets used to enjoying—much like how almost all mail is sent in sealed envelopes, whether or not its contents are sensitive—then it will be that much harder, for technical and/or social reasons, for an authority to take away. If Obfuscated TCP is even a token step in that direction (and it seems to be a bit better than that), then it is probably a good thing overall.
Someone earlier today on Slashdot was plugging Cory Doctorow's Little Brother, and I'm going to follow that example (you can read it for free!) [craphound.com] as part of it advances the same idea.
Reinventing ancient history (Score:5, Informative)
It's interesting how the same idea gets "reinvented" over and over. Opportunistic encryption using advertised DH public numbers is just such a thing.
ObsTCP is just a reinvention of SKIP.
See here via the Wayback Machine since the concept is long dead and buried.
http://web.archive.org/web/20021129230049/http://www.skip-vpn.org/ [archive.org]
Weak encryption worse than none. (Score:4, Insightful)
"By providing a less secure, but computationally and administratively cheaper, method of encryption, we might be able to..." give people a false sense of security.
Remember, weak encryption can be worse than none as Mary Queen of Scots found out at the cost of her life (see http://www.nikon.com/about/feelnikon/light/chap04/sec01.htm [nikon.com]).
Re:The implications? (Score:5, Interesting)
Why?
If you watch the "video", one of their explicit points (#2) is that the user shouldn't be informed of this. This will not trigger the little security lock icon. From a user's point of view, you shouldn't be able to tell if the web server you are connected to is unsecured or secured this this little bit of obfuscation.
This isn't for real security, it's to make simple sniffing harder. As the video puts it, it simply raises the bar for someone who wants to read other people's traffic.
It seems like a very good idea to me. It sounds quite intelligent (from what I know of TCP/IP, etc). Some protocols have need changes (protocols where there is one connection and it isn't dropped would need some way to communicate that the encryption is OK during the first (and possibly only) connection.
Either way, it sounds like quite an improvement over what we have now.
Parent
Arrgghh! No more videos! (Score:5, Insightful)
If you watch the video, your brain will leak out through your ears. It's terrible. Why produce a video which seems to be a black screen with a dark blue line wiggling when the person talks? Why pick a person with a crappy British accent and a speech impediment? Who's going to understand? Why flash up a couple of words here and there like "SSL" and "HTTP"? Why produce such a steaming pile of crap and call it an "introductory video"?
Instead, whoever is the video star in this could have written down their ideas in plain text. That would allow for easy reading and comprehension by people all over the world. Maybe I can read quickly. Maybe I don't want to sit around waiting for you to lisp and stammer through your presentation. Maybe I'd understand it better if I read it than if I heard it on a crappy video. Maybe I don't want to waste my bandwidth downloading several megabytes of video, where the same information in plain text might be a few kilobytes.
Parent
Re:Arrgghh! No more videos! (Score:4, Insightful)
I'm glad I'm not the only one who feels this way. It takes way more time to absorb information from a video - more than I'm usually willing to give.
If you must make a video, at least provide a transcript.
Parent
Re:The implications? (Score:5, Insightful)
It may be slightly off-topic but the parent has a VERY valid point. Self-signed sites are encrypted but best of luck trying to get people to use them thanks to the 3-clicks required and SMALL text. When I used the new firefox release I was even confused at first.
Now back to obfuscated TCP: This is on par with using NAT to fix the lack of IP addresses. Just fix the damn thing properly and stop screwing around with time wasting half-fixes (yeah they admitted it).
About the only thing this is going to do is make troubleshooting problems with Ethereal or other packet sniffers a pain in the a$$. Thanks.
Parent
Re:The implications? (Score:5, Interesting)
Self-certified certificates are worse than plain unencrypted traffic because of psychological reasons, not because of technical reasons.
Your ISP can easily and automatically intercept self-signed certificates and present their own certificate, which you will gladly accept. Now you think that you are less secure than a verified certificate but still "somewhat secure". Technically, you are however protected as much as plain unencrypted HTTP.
Now, this is where humans fail. Because you still think you are "somewhat safe", you will take higher risks, write things that you would normally not write, click on links that you perhaps wouldn't click on over a plain non-encrypted page. The famous false sense of security, which actually does nothing except making you feel good.
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Re:The implications? (Score:5, Insightful)
you're [sic] traffic's still encrypted and secure from eavesdropping
Except from the party that did the MITM attack, which is most often the party that you want to prevent watching your traffic, you know, the one that is actually interested in sniffing your traffic..
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Re:The implications? (Score:5, Funny)
This. Is. SLASHDOT!
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Re:The implications? (Score:5, Interesting)
Um, no. It's so that it costs more to index the web, meaning that any competitor to google has to pay more to challenge their dominant position as search engine. Microsoft has to bleed even more money trying to compete. Yahoo might have to abandon search.
TFA explains how Obfuscated TCP is both opportunistic and transparent. Servers will provide encrypted transmission only when the client requests it, and unlike SSL/TLS there is no additional handshaking required to setup the connection.
A car analogy. Suppose you use regular unleaded fuel in your car and it drives fine. High octane fuel then becomes available at a higher cost. Your car continues to drive fine on regular unleaded, but you have the choice to fill up with high octane at any petrol station that serves it.
This costs you more, how?
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Re:The implications? (Score:5, Insightful)
Parent
Re:The implications? (Score:5, Insightful)
Implications?
but it can assuage untargeted, dragnet sniffing of backbones
Can you read the subtext there? Snap, how's that for an implication? Privacy. (from the government.)
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Re:So, wait... (Score:5, Informative)
It's not written by Google, it's just hosted by them. Big difference, misleading title.
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Re: (Score:3, Insightful)
>
Are we supposed to like Google or not now?
I'm confused :(
Realizing that large corporations consist of many separate interests might help alleviate your confusion :-)
Project owner's page is at: http://www.imperialviolet.org/ [imperialviolet.org] if you wanted more info.
Re:Problem isn't computation... (Score:5, Informative)
I would disagree. One of the biggest barriers to implementing SSL on my sites is the lack of IP addresses. I only have two IP addresses, yet I host 16 web sites. My understanding is that HTTPS requires IP based virtuals which would prevent me from hosting more than two sites if I were to use SSL for all of my sites.
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Re:Problem isn't computation... (Score:5, Informative)
My understanding is that HTTPS requires IP based virtuals
Partly. There's a TLS extension [wikipedia.org] that makes it work, but it looks like it doesn't work for IE on WinXP.
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Re:Problem isn't computation... (Score:5, Insightful)
Anybody remembers what hapenned to RFC 2817 [ietf.org] ? It tried to address this very pb by introducing the "Upgrade: TLS/1.0" header and the "426 Upgrade Required" status code, but I don't think any browser or server implement them.
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Re:Problem isn't computation... (Score:5, Insightful)
Running your web sites on non-standard ports is a great way for your web site not to be accessible to users accessing the internet through firewalls that limit egress traffic based on TCP destination ports.
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Re:Problem isn't computation... (Score:5, Insightful)
For a public site using non-standard ports is an easy method to shoot yourself in the foot - you immediately block all users behind proxies or firewalls that only allow communication on "standard" web ports.
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Re:OE is a nice idea (Score:4, Informative)
That depends on your definition of "not realized". Before the FreeS/WAN project was abandoned, opportunistic encryption had been implemented and was in use. Adoption was probably quite small, but it existed.
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