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Why not DANE in browsers

imperialviolet.org

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Re: Why not DANE in browsers

#21

Post by Panino »

derf_ wrote: post #14
tptacek wrote: post #7

Earlier quoted context omitted.

How does securing DNS lookups solve the MITM problem if the underlying traffic remains unencrypted? If you encrypt the traffic, you don't need secure DNS anymore.

That depends on what your trust model is. Somebody is resolving the DNS query, and then the result gets transmitted to you. If all you're worried about the result being MITM'd during transit, then encryption is sufficient. You can set up DNSCrypt to deal with this today [1]. But often the provider resolving the query is itself untrustworthy. Most providers these days (including OpenDNS) redirect invalid queries to th…

> Most providers these days (including OpenDNS) redirect invalid queries to their own landing pages

OpenDNS stopped doing this on June 6 2014:

http://blog.opendns.com/2014/05/29/no-more-ads/

Re: Why not DANE in browsers

#22

Post by tlb »

tptacek wrote: post #11
tlb wrote: post #9

The fact that TXT records don't work for some people shouldn't stop us. Anything that isn't currently widely used is broken for lots of people, because that's how networks are administered. Once it gets deployed and people start complaining, any specific network problem will get fixed. Delaying proper network security because it won't currently work for a few percent of people seems like a recipe for never getting th…

It's a cost-benefit issue. Do you believe DNSSEC is so valuable that it's worth (a) breaking connectivity for a significant number of people and (b) incurring the expense of replacing/upgrading the middleboxes that are breaking connectivity? If so, why?

I don't have a strong opinion on DNSSEC itself. It seems like it might be a good idea for email, at least.

I don't have much sympathy for network admins who block TXT records because it doesn't currently seem to break anything. TXT records are part of the spec, and if some of them have configured something to block them, that's not a good reason for everyone to not have secure systems.

Re: Why not DANE in browsers

#23

Post by cpach »

tptacek wrote: post #20
101914 wrote: post #19

I'm reading these blogged opinions on DNSSEC and DANE and I notice that they never state the problem(s) that these "solutions" are meant to address. At least not explicitly. Somehow I doubt it, but if by chance there is only one true problem being addressed and that problem is simply how do we authenticate another computer as being who we believe her to be, then my second question is: what is wrong with SSH authentic…

SSH authentication works fine.

It does. But as we all know that model can’t just be lifted over to WWW.

Re: Why not DANE in browsers

#24

Post by derf_ »

Panino wrote: post #21
derf_ wrote: post #14

Earlier quoted context omitted.

That depends on what your trust model is. Somebody is resolving the DNS query, and then the result gets transmitted to you. If all you're worried about the result being MITM'd during transit, then encryption is sufficient. You can set up DNSCrypt to deal with this today [1]. But often the provider resolving the query is itself untrustworthy. Most providers these days (including OpenDNS) redirect invalid queries to th…

> Most providers these days (including OpenDNS) redirect invalid queries to their own landing pages OpenDNS stopped doing this on June 6 2014: http://blog.opendns.com/2014/05/29/no-more-ads/

Something about which I'm glad to be wrong.

Re: Why not DANE in browsers

#25

Post by teddyh »

Panino wrote: post #21
derf_ wrote: post #14

Earlier quoted context omitted.

That depends on what your trust model is. Somebody is resolving the DNS query, and then the result gets transmitted to you. If all you're worried about the result being MITM'd during transit, then encryption is sufficient. You can set up DNSCrypt to deal with this today [1]. But often the provider resolving the query is itself untrustworthy. Most providers these days (including OpenDNS) redirect invalid queries to th…

> Most providers these days (including OpenDNS) redirect invalid queries to their own landing pages OpenDNS stopped doing this on June 6 2014: http://blog.opendns.com/2014/05/29/no-more-ads/

OpenDNS could still turn ads on again at any time. And the censorship and subversion arguments are still valid.

Re: Why not DANE in browsers

#26

Post by gsnedders »

101914 wrote: post #19

I'm reading these blogged opinions on DNSSEC and DANE and I notice that they never state the problem(s) that these "solutions" are meant to address. At least not explicitly. Somehow I doubt it, but if by chance there is only one true problem being addressed and that problem is simply how do we authenticate another computer as being who we believe her to be, then my second question is: what is wrong with SSH authentic…

> what is wrong with SSH authentication?

You need some secure, out-of-band, communication means to transfer the key fingerprint to be able to verify it. The whole aim of the CA structure is so I don't need to somehow find a secure means to contact Amazon to verify their key fingerprint prior to first connecting to their website.

Re: Why not DANE in browsers

#27

Post by Nimi »

tptacek wrote: post #2

The meatiest bit of this article, which is great: Attackers control connectivity. Connectivity is expensive. Connectivity is also unreliable: captive portals, proxies, and firewalls break it. These factors make OCSP certificate revocation unworkable. For similar reasons, they make DANE's ostensible safeguard against malicious CAs unworkable. In practice, DANE would probably only be usable as an additional CA; it woul…

Slightly off-topic: Could you please add RSS support to your "blog"? I'm sure others, besides me, would love to me notified of new entries. Thanks!

Re: Why not DANE in browsers

#28

Post by 101914 »

gsnedders wrote: post #26
101914 wrote: post #19

I'm reading these blogged opinions on DNSSEC and DANE and I notice that they never state the problem(s) that these "solutions" are meant to address. At least not explicitly. Somehow I doubt it, but if by chance there is only one true problem being addressed and that problem is simply how do we authenticate another computer as being who we believe her to be, then my second question is: what is wrong with SSH authentic…

> what is wrong with SSH authentication? You need some secure, out-of-band, communication means to transfer the key fingerprint to be able to verify it. The whole aim of the CA structure is so I don't need to somehow find a secure means to contact Amazon to verify their key fingerprint prior to first connecting to their website.

What if I do not want to transfer the key over an insecure network of computer networks that are trivial to tamper with?

What if I would prefer to look up or obtain the key via some other means (that I deem more trustworthy that the internet)?

Re: Why not DANE in browsers

#29

Post by 101914 »

cpach wrote: post #23
tptacek wrote: post #20

Earlier quoted context omitted.

SSH authentication works fine.

It does. But as we all know that model can’t just be lifted over to WWW.

Note sure what "lifted over" means exactly.

I once explained PKI to someone in their 70's who grew up without the personal computer and at one point they stopped me and asked "Why don't they just publish their public key in the newspaper or some directory like a telephone book?"

Later, as an experiment I printed a public key and then used OCR to reproduce it electronically.

Of course a key intended for www usage can also be retrieved over SSH, after the sending computer is authenticated (via SSH authentication). I have also done this, again as an experiment.

Re: Why not DANE in browsers

#30

Post by cpach »

101914 wrote: post #28
gsnedders wrote: post #26

Earlier quoted context omitted.

> what is wrong with SSH authentication? You need some secure, out-of-band, communication means to transfer the key fingerprint to be able to verify it. The whole aim of the CA structure is so I don't need to somehow find a secure means to contact Amazon to verify their key fingerprint prior to first connecting to their website.

What if I do not want to transfer the key over an insecure network of computer networks that are trivial to tamper with? What if I would prefer to look up or obtain the key via some other means (that I deem more trustworthy that the internet)?

What key are you referring to here? The CA’s root certificate?
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