January 17, 2017

Mozilla Debates Whether to Trust Chinese CA

[Note our follow-up posts on this topic: Web Security Trust Models, and Web Certification Fail: Bad Assumptions Lead to Bad Technology]

Sometimes geeky technical details matter only to engineers. But sometimes a seemingly arcane technical decision exposes deep social or political divisions. A classic example is being debated within the Mozilla project now, as designers decide whether the Mozilla Firefox browser should trust a Chinese certification authority by default.

Here’s the technical background: When you browse to a secure website (typically at a URL starting with “https:”), your browser takes two special security precautions: it sets up a private, encrypted “channel” to the server, and it authenticates the server’s identity. The second step, authentication, is necessary because a secure channel is useless if you don’t know who is on the other end. Without authentication, you might be talking to an impostor.

Suppose you’re connecting to https://mail.google.com, to pick up your Gmail. To authenticate itself to you, the server will (1) do some fancy math to prove to you that it knows a certain encryption key, and (2) present you with a digital certificate (or “cert”) attesting that only Google knows that encryption key. The cert is created by a Certification Authority (“CA”), which asserts that it has done the necessary due diligence to establish that the designated encryption key is known only to Google Inc.

If the CA is competent and honest, then you can rely on the cert, and your connection will be secure. But a dishonest CA can trick you into talking to an impostor site, so you need to be cautious about which CAs you trust. Your browser comes preinstalled with a list of CAs whom it will trust. In principle you can change this list, but almost nobody does. So browser vendors effectively decide which CAs their users will trust.

With this background in mind, let’s unpack the Mozilla debate. What set off the debate was the addition of the China Internet Network Information Center (CNNIC) as a trusted CA in Firefox. CNNIC is not part of the Chinese government but many people assert that it would be willing to act in concert with the Chinese government.

To see why this is worrisome, let’s suppose, just for the sake of argument, that CNNIC were a puppet of the Chinese government. Then CNNIC’s status as a trusted CA would give it the technical power to let the Chinese government spy on its citizens’ “secure” web connections. If a Chinese citizen tried to make a secure connection to Gmail, their connection could be directed to an impostor Gmail site run by the Chinese government, and CNNIC could give the impostor a cert saying that the government impostor was the real Gmail site. The Chinese citizen would be fooled by the fake Gmail site (having no reason to suspect anything was wrong) and would happily enter his Gmail password into the impostor site, giving the Chinese government free run of the citizen’s email archive.

CNNIC’s defenders respond that any CA could do such a thing. If the problem is that CNNIC is too close to a government, what about the CAs already on the Firefox CA list that are governments? Isn’t CNNIC being singled out because it is Chinese? Doesn’t the country with the largest Internet population deserve at least one slot among the dozens of already trusted CAs? These are all good questions, even if they’re not the whole story.

Mozilla’s decision touches deep questions of fairness, trust, and institutional integrity that I won’t even pretend to address in this post. No single answer will be right for all users.

Part of the problem is that the underlying technical design is fragile. Any CA can certify to any user that any server owns any name, so the consequences of a misplaced trust decision are about as bad as they can be. It’s tempting to write this off as bonehead design, but in truth the available design options are all unattractive.

Google Threatens to Leave China

The big news today is Google’s carefully worded statement changing its policy toward China. Up to now, Google has run a China-specific site, google.cn, which censors results consistent with the demands of the Chinese government. Google now says it plans to offer only unfiltered service to Chinese customers. Presumably the Chinese government will not allow this and will respond by setting the Great Firewall to block Google. Google says it is willing to close its China offices (three offices, with several hundred employees, according to a Google spokesman) if necessary.

This looks like a significant turning point in relations between U.S. companies and the Chinese government.

Before announcing the policy change, the statement discusses a series of cyberattacks against Google which sought access to Google-hosted accounts of Chinese dissidents. Indeed, most of the statement is about the attacks, with the policy change tacked on the end.

Though the statement adopts a measured tone, it’s hard to escape the conclusion that Google is angry, presumably because it knows or strongly suspects that the Chinese government is responsible for the attacks. Perhaps there are other details, which aren’t public at this time, that further explain Google’s reaction.

Or maybe the attacks are just the straw that broke the camel’s back — that Google had already concluded that the costs of engagement in China were higher than expected, and the revenue lower.

Either way, the Chinese are unlikely to back down from this kind of challenge. Expect the Chinese government, backed by domestic public opinion, to react with defiance. Already the Chinese search engine Baidu has issued a statement fanning the flames.

We’ll see over the coming days and weeks how the other U.S. Internet companies react. It will be interesting, too, to see how the U.S. government reacts — it can’t be happy with the attacks, but how far will the White House be willing to go?

Please, chime in with your own opinions.

[UPDATE (Jan. 13): I struck the sentence about Baidu’s statement, because I now have reason to believe the translated statement I saw may not be genuine.]

U.S. Objects to China's Mandatory Green Dam Censorware

Yesterday, the U.S. Commerce Secretary and Trade Representative sent a letter to China’s government, objecting to China’s order, effective July 1, to require that all new PCs sold in China have preinstalled the Green Dam Youth Escort censorware program.

Here’s today’s New York Times:

Chinese officials have said that the filtering software, known as Green Dam-Youth Escort, is meant to block pornography and other “unhealthy information.”

In part, the American officials’ complaint framed this as a trade issue, objecting to the burden put on computer makers to install the software with little notice. But it also raised broader questions about whether the software would lead to more censorship of the Internet in China and restrict freedom of expression.

The Green Dam requirement puts U.S.-based PC companies, such as HP and Dell, in a tough spot: if they don’t comply they won’t be able to sell PCs in China; but if they do comply they will be censoring their customers’ Internet use and exposing customers to serious security risks.

There are at least two interesting new angles here. The first is the U.S. claim that China’s action violates free trade agreements. The U.S. has generally refrained from treating China’s Internet censorship as a trade issue, even though U.S. companies have often found themselves censored at times when competing Chinese companies were not. This unequal treatment, coupled with the Chinese government’s reported failure to define clearly which actions trigger censorship, looks like a trade barrier — but the U.S. hasn’t said much about it up to now.

The other interesting angle is the direct U.S. objection to censorship of political speech. For some time, the U.S. has tolerated China’s government blocking certain political speech in the network, via the “Great Firewall“. It’s not clear exactly how this objection is framed — the U.S. letter is not public — but news reports imply that political censorship itself, or possibly the requirement that U.S. companies participate in it, is a kind of improper trade barrier.

We’re heading toward an interesting showdown as the July 1 date approaches. Will U.S. companies ship machines with Green Dam? According to the New York Times, HP hasn’t decided, and Dell is dodging the question. The companies don’t want to lose access to the China market — but if U.S. companies participate so directly in political censorship, they would be setting a very bad precedent.