So, let us talk plainly. You absolutely, definitely, positively should be using TLS / HTTPS encryption on the sites that you run.

HTTPS provides encryption, meaning that anyone watching the connection (and yes, people do care, and are absolutely watching), will have a harder time trying to extract content information about the connection. This is important, because it stops your credit card being read as it makes its way to Amazon’s servers, or your password being read when you log into your email.

When I advise my clients on infrastructure, these days I recommend that all pages on a website, regardless of that page’s contents, should be served over HTTPS. The primary reason being a feature of an encrypted connection which I don’t think gets underlined enough.

Tamper resistant web

When you serve content over HTTPS, it is significantly harder to modify. Or, to put it another way, when you serve pages unencrypted, you have absolutely no guarantee that the page your server sends is going to be the page that your visitor receives!

If an attacker controls a link in the chain of computers between you and the site you’re visiting it is trivial to modify requests to and from a visitor and the server. A slightly more sophisticated attacker can perform these attacks without the need to control a link in the chain, a so called “Man on the side” attack – more technically complex, but still relatively trivial with sufficient budget, and has been widely automated by state actors and criminal gangs.

The capabilities these sorts of attacks give someone are limited only by budget and imagination. On a sliding scale of evil, possibly the least evil use we’ve seen in the wild is probably the advertising injection attack used by certain ISPs and Airplane/hotel wifi providers, but could easily extend to attacks designed to actively compromise your security.

Consider this example of an attack exploiting a common configuration:

  • A web application is installed on a server, and the site is available by visiting both HTTP and HTTPS endpoints. That is to say, if you visited both http://foo.com and https://foo.com, you’d get the same page being served.
  • Login details are sent using a POST form, but because the developers aren’t complete idiots they send these over HTTPS.

Seems reasonable, and I used to do this myself without seeing anything wrong with it.

However, consider what an attacker could do in this situation if the page serving the form is unencrypted. It would, for example, be a relatively trivial matter, once the infrastructure is in place, to simply rewrite “https://” to “http://”, meaning your login details would be sent unencrypted. Even if the server was configured to only accept login details on a secure connection (another fairly common practice), this attack would still work since the POST will still go ahead. A really sophisticated attacker could intercept the returning error page, and replace it with something innocuous, meaning your visitor would be non the wiser.

It gets worse of course, since as we have learnt from the Snowden disclosures, security agencies around the world will often illegally conscript unencrypted web pages to perform automated attacks on anyone they view as a target (which, as we’ve also learnt from the Snowden disclosures, includes just about everybody, including system administrators, software developers and even people who have visited CNN.com).

Lets Encrypt!

Encrypting your website is fairly straightforward, certainly when compared to the amount of work it took to deploy your web app in the first place. Plus, with the new Lets Encrypt project launching soon, it’s about to get a whole lot easier.

You’ll need to make sure you test those configurations regularly, since configuration recommendations change from time to time, and most shared hosts & default server configurations often leave a lot to be desired.

However, I assert that it is worth the extra effort.

By enabling HTTPS on the entire site, you’ll make it much much harder for an attacker to compromise your visitor’s privacy and security (I say harder, not impossible. There are still attacks that can be performed, especially if the attacker has root certificate access for certificates trusted by the computer you’re using… so be careful doing internet banking on a corporate network, or in China).

You also add to the herd immunity to your fellow internet users, normalising encrypted traffic and limiting the attack surface for mass surveillance and mass packet injection.

Finally, you’ll get a SEO advantage, since Google is now giving a ranking boost to secure pages.

So, why wait?

So yesterday, we were greeted with another bombshell from the Snowden archives.

After finding out the day before that GCHQ had spied on lawyers, we now find out that GCHQ and the NSA conspired to steal the encryption keys to pretty much every sim card in the world, meaning that they can easily break the (admittedly weak) encryption used to protect your phonecalls and text messages.

Personally, I’m not terribly concerned about this, because the idea that your mobile phone is insecure is hardly news. What is of concern to me, is how they went about getting those keys.

It seems that in order to get these keys, the intelligence agencies hunted down and placed under invasive surveillance ordinary innocent people, who just happened to be employed by or have dealings with the companies they were interested in.

The full capabilities of the global surveillance architecture they command was deployed against entirely unremarkable and innocent individuals. People like you and me, who’s entire private lives were sifted through, just in case they exposed some information that could be used against the companies which they worked.

Nothing to hide, nothing to fear

If there is a silver lining in all this, with any luck it will go some way towards shattering the idea that because you have nothing to hide, you have nothing to fear.

This is, primarily, a coping strategy. It’s a lie people tell themselves so they can avoid confronting an awkward or terrifying fact, a bit like saying climate change isn’t real, or that smoking won’t kill me.

Generally, it is taken to mean that you’ve done nothing wrong, i.e. illegal (and of course, that’s not what privacy is about, and what you consider being “wrong” has typically not been the same as what those in power consider “wrong”).

Fundamentally, it misses the point that you don’t get to decide what others are going to find interesting, or suspect you of knowing. In this instance, innocent people had their privacy invaded purely because they had suspected access to information that the intelligence agencies found interesting. This is something that, were I to do something similar, I’d go to jail for a very long time.

Now consider that one of the NSA’s core missions is to advance US economic interests, spying on Brazilian oil companies and European trade negotiations, etc. If I worked at a competitor of a US company, I’d be very careful what I said in any insecure form of communication.

You do have something to hide.

GCHQoogle: so much for "Don't be evil"Given what we now know about the mass surveillance, and attack on the infrastructure of the internet, conducted by Britain’s GCHQ and America’s NSA (as well as their Chinese, Russian, German, etc counterparts).

Given that we now know, for a fact, that almost every byte of non-encrypted traffic is recorded and analysed, shouldn’t we now make a concerted effort to finally deprecate vanilla HTTP in favour of HTTP over TLS (HTTPS)?

When you use HTTP, it is a trivial matter for an attacker to see the content of the pages you visit, when, and how often you visit them. When using HTTP, there is also no guarantee that the content of the page hasn’t been modified without your knowledge, exposing you to all kinds of attacks.

Encryption, by and large, removes these problems, as well as massively increasing the cost of mass surveillance. Is it not time for all of us, as well as standards organisation like the IETF, push to make HTTPS the default? Even during my time I’ve seen insecure protocols like telnet and FTP go from widespread use to being almost completely replaced by secure alternatives (ssh and scp), so could we not do the same with HTTP?

Certificate authorities

Ok, there is one big difference between HTTPS and ssh (ok, many many, but one I care about here), and that is that HTTPS relies on certificate authorities. These are necessary in order to distribute trust, so that browsers can know to automatically accept a certificate and verify the server it is connecting to is who it says it is.

This is much nicer for the average user than, say, manually verifying the server’s fingerprint (as you have to do with SSH), but comes with some pretty serious problems if we were to make it default:

  • Every site owner would have to get a certificate, and these can only be obtained by a certificate authority if you don’t want browsers to pop up a big red warning, meaning we further bake these guys in to the Internet’s DNA.
  • Certificate authorities can be directly pressured by governments, so, a government attacker could MITM you on a secure connection and present you with a certificate that your browser accepts as valid, and so will give you no warning (of course, this is much more costly than the blanked mass surveillance that is currently going on).
  • Getting a certificate either costs money, and/or has restrictions placed on their use (for example, no commercial use, in the case of StartCom). This is really bad, since it essentially requires permission from a third party to launch a site.

It is this last causes me most concern, since it essentially provides an easy way of suppressing minority views.

Imagine that we lived in a world where HTTP had been deprecated, and browsers no longer supported unencrypted HTTP, or could, but you had to request it specifically (essentially the reverse of what we currently have). You wanted to launch a site that expressed a minority view – perhaps you were critical of your government, or you wanted to leak some information about crimes being committed, is it not inconceivable that you could have trouble obtaining a certificate? Given that certificate authorities are companies who worry about their bottom line, and are a convenient point for the bad guys to apply pressure?

If you couldn’t get a certificate in this environment, it could dramatically reduce the audience that would see your site.

So, perhaps before we move to deprecate HTTP, we must first find a better way than certificate authorities to distribute trust? How could we accomplish this? Perhaps we could take advantage of the fact that most people’s browsers automatically update, and so we could distribute browsers with expected certificates for sites hard coded into them (giving an added advantage that we could pin certificates)?

Anyway, its complicated, and I’m thinking aloud here… what are your thoughts?