Revocation still doesn't work

https://www.imperialviolet.org/2014/04/29/revocationagain.html?radio

by wglb • 12 years ago

44 12 12 years ago

danielweber2• 12 years ago

Best summary I've seen:

"If the bad guy can MITM your browser going to www.bank.com, they can break your browser going to the online revocation list."

(Implicit: the browser will fail open to connect to the website anyway in case it can't connect to the revocation list.)

gojomo3• 12 years ago

If the revocation data is available from "everywhere", and the browser sees that it hasn't been able to get it recently from "anywhere", that's a suitably alarming situation that the user should get a blocking warning, as with any other self-signed/untrusted-CA certificate.

In the usual browsing situation, it also doesn't have to be a blocking verification before displaying the first bytes from a site (requiring subsecond checking). It could load the page but continue verification in the background, only becoming a blocking warning some number of seconds later, when the user enters form data or attempts other navigation.

In fact, even minutes into a session, the information that either – (a) it took a while but we now see that this certificate is definitely bad; or (b) you are currently so cut-off from the real "Internet" that suspicion towards all sites is justified – is useful.

That is, even a "delayed hard fail" would still be useful.

The alternative is that people chat, transact, etc. indefinitely at the mercy of attackers, because the browser isn't even trying to acquire good data via censor-resistant channels.

danielweber2• 12 years ago

You have to keep the online revocation service up all the time. People will DDoS just for the lulz it causes when it being broken breaks everyone's browser.

While sitting in a meeting I realized there is one situation that online revocation helps: someone steals bank.com's DNS record. They can't necessarily MITM anyone with that.

But, TACK is probably a better countermeasure there.

gojomo3• 12 years ago

It's the fatalism about fixing this is most discouraging in Langley's writings.

Why shouldn't someone who cares very much about security be able to tell their browser to get the full 30MB it would require today, or the 300MB Langley projects it will take in 5 years? That's not that much data!

(Google's hand-curated tiny CRLSet lifeboat is currently only ~308KB of blacklisted certificate data.)

Why can't the organizations with multi-hundred-million-dollar budgets for web projects design the privacy-preserving/space-saving/probabilistic systems that would make this work with much smaller overhead?

Once the original site, the CA, and a major browser vendor all know, via public info, that a certificate is compromised, why should any browser user have to wait days/weeks/months/indefinitely, while showing the false "lock icon", before warning users?

thirsteh• 12 years ago

That's the thing I don't understand about this whole discussion: The SafeBrowsing blacklist bloom filter that Google itself made and uses is significantly smaller, is updated in real time, and doesn't have a big runtime overhead. Why not just have a bloom filter for revocations, with a Google server doing the false-positive elimination?

(Yes, there is a little bit of a chicken-and-egg problem when it comes to the Google server, but that's a much smaller problem than being unable to check if most certificates in the world are revoked or not.)

Edit: Looks like Adam (of course) already considered this: https://www.imperialviolet.org/2011/04/29/filters.html

anaphor• 12 years ago

This just reads as rationalization for why Chrome is the best browser. Nobody has come up with a perfect solution to the revocation problem, but if you want the ability to actually check with the OCSP responder and fail if it cannot be reached, then you should be using Firefox, not Chrome (also if you don't want Google controlling every single aspect of what you do).

joshpeek• 12 years ago

It seems like Langley and Gibson both agree that OCSP Must-Staple would resolve all this.

"If we want a scalable solution to the revocation problem then it's probably going to come in the form of short-lived certificates or something like OCSP Must Staple." - https://www.imperialviolet.org/2014/04/19/revchecking.html

"The case for “OCSP Must-Staple" - https://www.grc.com/revocation/commentary.htm

yuhong• 12 years ago

Personally, I am for a hard fail OCSP option in HSTS or certificate plus OCSP stapling. Default to soft fail with a warning message for now. Remember captive portals can use OCSP stapling too.

dsl• 12 years ago

Do people still take GRC seriously?

Back in 2001-2002 people dedicated a lot of time to debunking his every statement, but he just sort of faded into the nether after TechTV blew up. He still however maintains his charlatan listing: http://attrition.org/errata/charlatan/steve_gibson/

datapolitical• 12 years ago

This is some of the most awful writing I've seen on the HN front page in a while. I'm sure if you're well-versed in the issues surrounding revocation the discussion makes a great deal of sense.

For the rest of us, it's a forrest of technical jargon, which is stunning to me given that the concepts at play here aren't insanely complicated.

So I think the claim is that doing blocking OCSP lookups is a good idea because, if you use CAPI on Windows, then you might cache 50 OCSP responses for a given CA certificate. Then you'll download and cache a CRL for a while and then, depending on whether the CA splits their CRLs, you might have some revocations cached for a site that you visit.

nkurz• 12 years ago

I'm sure if you're well-versed in the issues surrounding revocation the discussion makes a great deal of sense.

I think you've summarized the traditional appeal of Hacker News: items for experts, written by experts, discussed by experts. Even if it's not a field that I understand (what better way to learn?) I'm always glad to see these articles on the front page, for it means the real HN is still alive, deep within.

Revocation still doesn't work

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