Why don’t big publishers use https instead of https? The discussion comes up every three to six months at the Guardian and there seems to be no technical barrier to doing this. There has been a lot of talk about where the secure termination happens and how to get certificates onto the CDN but there seem to be good answers to all the good questions. There doesn’t seem to be any major blockers or even major disadvantages in terms of network resources.

So why doesn’t it happen? Well public content publishers are dependent for the most part on advertising and online advertising is a total mess.

Broken and miss-configured advertising is a major source of issues and the worst aspect of the situation is that you really don’t have much control over what is happening. When you call out to the ad server you essentially yield control to whatever the ad server is going to do.

Now your first-level campaigns, the stuff that are in-house, premium or bespoke campaigns are usually designed to run well on the site and issues with this are often easy to fix because you can talk to your in-house advertising operations team.

However in a high-volume site this is a tiny amount of the advertising you run because you tend to have a much larger inventory (capacity to serve ads) in practice than you can sell. That is generally because supply of online advertising massively outstrips demand.

The way the discrepancy is made good is via ad exchanges which are really clever pieces of technology that try to find the best price for available both publisher and ad buyer. Essentially the ad exchanges try to establish a spot price for an available ad slot amongst all the campaigns the buyers have set up.

However you have virtually no say over what the format of the advert the exchange is going to serve up. The bundle of content that makes up the ad is called the “creative” and might be a simple image but more likely is a script or iframe that is going to load the actual advert, run personalisation and tracking systems.

You have no real control as to what the creatives are and they certainly haven’t been written with your site in mind and most probably security is a very minimal concern compared to gathering marketing information on your view.

So if the creative contains any security breaking rule or any resource that is not also https they you get a security exception on the site. The customer then blames you for being insecure.

One of our consumer products, which do all run under https, ran ads and every other month this issue would come up. In the end we decided that the value of the subscription was more than the value of any advertising that was undermining the image of being secure and reliable so we took the advertising off.

And therefore until agencies and ad exchanges change their policies so that ads are only served off https this situation is unlikely to change. Ironically there is no reason for ads to be served off https since they don’t want to be cached and wants to do lots of transactional stuff with the client anyway.

If the online advertising business went secure-only then online publishers would be able to follow them. Until then public pages are likely to remain on http.