Will Certificate Authorities Become Targets for DMCA Takedowns?

It’s the year 2022, and the Web is mostly encrypted: HTTPS is ubiquitous, having extended its reach into the long tail of small sites that were slow to adopt it. Browsers no longer show green locks for regular, domain-validated HTTPS sites, but they do show red indicators or warnings when something is plaintext or the encryption is weak.

PKI has matured, too. Certificate revocation is widely enforced but not often used because certificate lifetimes are so short: less than a week, or even just a few hours. Because of the automation of certificate issuance, CAA records are set in DNS for almost all registered domains. These records specify which certificate authorities (CAs) are allowed to issue certificates for that name. All this, coupled with robust Certificate Transparency logs, has made the Internet more secure and reliable.

Web technology has come far since the explosion of the Internet nearly thirty years ago. Policy, on the other hand, has crawled. This is not unusual: policymakers tend to be in high positions in government or industry where the process of making change is arduous, tedious, and controversial.

There’s still this thing called the DMCA. Copyright holders deploy their attorneys for a kind of Shock-and-Awe tactic, before they pull out the big guns called litigation. Site owners, web hosts, domain registrars, and DNS providers are all common targets for letters demanding takedown of content that allegedly violates DMCA. Internet companies typically comply according to their own policies or as the law requires.

A lawyer need only be successful in convincing one of those four “choke points” by threatening legal action in order to suffocate the site. (There are others, like ISPs, which operate more generally, and we skip them for brevity.) These entities totally control the site’s availability, which is one crucial dimension of secure systems. Here they are again:

• Site owner. He or she can voluntarily remove the site/content.
• Web host. They can destroy the site owner’s account or files.
• Domain registrar. They can cancel or transfer ownership of the domain name.
• DNS provider. They can make the site inaccessible via hostname.

Now that it’s 2022, a site needs HTTPS in order to be trusted by browsers. At very least, this means they show an indicator above the page. Maybe it even means the browser shows a warning before navigating to the site. Either way, HTTPS is critical to a site’s availability and integrity.

DMCA lawyers are clever, and they realize this emerging trend. They contact a site’s CA and demand the site be disconnected for violating the law (despite lack of a court case). The CA, operating without policy for such requests and afraid of legal ramifications, revokes the site’s certificate.

Within hours, browsers begin to refuse connecting to the site on port 443 and warning flags fly instead, scaring users away. Browsers don’t revert to port 80 anymore because HTTPS is expected and using HTTP is effectively a downgrade attack. Visitors aren’t sure what to do, and the site goes offline around the globe.

So we add another entity to our list of controlling agents:

• Certificate authority. They can revoke certificates or refuse to issue.

And the lawyers are very pleased with their newfound power.

Although this tale is hypothetical (as far as I know), this touches on larger questions that are already relevant:

1. Should CAs police the Web?
2. How can we protect CAs from being coerced into involuntary action?

With regards to (1), my answer (and I am not alone) is no. The reason for it is a worthy of a whole post unto itself, and I won’t get into it here.

The answer to (2) is less straightforward. There are several aspects to consider:

• CAs are an attractive target for adversaries (government agencies, attorneys, and militant groups come to mind) because of one unique property: CAs can affect the connectivity and destroy the trust of a site without needing any access to it or its domains. Even if browsers of the future allow downgrading to HTTP, a site that is forced into plaintext is trivial to manipulate. Interested parties can change the text or images on its pages, inject malware or ads, and the site becomes a serious liability to the owner, putting all their visitors (and the site’s own reputation) at risk.
• After a certificate is forcefully revoked, the adversary may continue to press until that CA — and any others —agree not to issue new certificates for that site. CAA records focus this attack drastically, since only specific CAs need comply.
• Cease & Desist letters (or DMCA takedown requests) seldom require a trial to be effective. The threat of legal action is all-too-often sufficient to coerce companies to take action against their customers, even if the claim is unjustified. (Site owners may not have money to fight a legal battle.)
• The motivation for this behavior is not limited to DMCA. What if someone feels that a domain or site infringes their trademark? Isn’t that for a court to decide? To muddy the waters a bit, suppose PayPal approaches a CA and demands a revocation of all certificates with the name “PayPal” in it and for the CA to refuse to issue any more certificates containing its name, on the grounds that they are enforcing their trademark; then they show that several (but not all) of those sites are used for phishing. What should the CA do?
• Beyond legal issues, CAs could be ripe targets for government agencies, oppressive regimes, and really rich jerks. Basically, as our reliance on HTTPS and PKI grows, the CA becomes a really cheap way to perform DoS.
• The issuance of wildcard or SAN certificates amplifies fallout. A CA that is forced to revoke (or refuse issuance of) a wildcard certificate could be affecting thousands of sites, albeit likely related ones. Revoking (or refusing to issue) a SAN certificate could impact hundreds of unrelated sites. It would be interesting if a CA had more solid grounds to refuse demands if carrying them out would harm other, uninvolved sites.
• Legal action is not unfamiliar to popular web hosts, registrars, ISPs, etc. However, CAs may not be equipped (in policy, training, or technology) to handle these kinds of requests.
• Typically, companies notify their customer when legal action against them is being threatened (hopefully before taking any action against the account). With CAs, this is not always possible. For example, Let’s Encrypt allows anyone to obtain a certificate without providing even an email address (but they — and I — strongly recommend always giving a valid email address!).

It is in our best interest to help relieve the pressure points for CAs. What can we do towards this? I have only a few ideas right now.

• One obvious thing is to abide the law where we live. It gets complicated for sites that are communities where others can upload or post their own content. Plus, interpretation of the law is fuzzy at best. What may be illegal or incriminating according to one judge or jury isn’t to another.
• Revocations should require a reason to be attached. As certificate automation grows, it will be crucial for servers to be able to handle revocation situations properly.
• CAs publishing transparency reports (more than just CT) would help the public know if CAs are taking heat.

But perhaps the long-term solution is for governments to respect the free (as in freedom) operation of CAs and sites and the use of encryption everywhere. It would be ideal if CAs had the freedom to refuse demands to revoke or not issue certificates from anyone other than the subject.

History has repeatedly shown that the pen is mightier than the sword. Is policy mightier than encryption? We’ll see. I hope we won’t have to rely on clever math to ensure privacy and security because our policies become so invasive, unstable, and oppressive.

The good news is that efforts are being made on both technology and policy fronts to advocate freedom and privacy.

Encryption technology is pretty good at providing confidentiality and integrity, but it’s not great at deniability or when the user is under duress.

Policy varies around the world, but it’s generally good at keeping systems available (e.g. infrastructure) and fueling the race for better technologies. But it’s not so good at understanding encryption or preserving our privacy. It is also prone to corruption.

Clearly, we have a lot of challenges ahead of us in the technology and policy sectors.

End notes

1. If you think privacy is important and HTTPS should be ubiquitous, consider using Caddy as your web server. For each site that switches, thousands of visitors benefit.
2. I’m happy to speak about TLS/HTTPS or anything related to Caddy at meetups or conferences this summer, so long as the arrangement is compatible with my budget as a graduate student. Feel free to reach out!
3. Speaking of graduate students: if you are doing research, let me know if Caddy might be of assistance in your research.