Google behavioral ads tap DoubleClick eyeball

So, Google is now using your surf history to tailor online ads to your particular online interests. It's a rather creepy thought, but that's not the problem. The problem is that Google won't say how much of your surf history it's capturing - or how long it plans on keeping this potentially ginormous data hoard.

When Google announced its "interest-based advertising" program on March 11, it said the program would target ads on YouTube and the many third-party sites in its AdSense network. And with a new FAQ, Google mentions that these ads would be targeted using data collected via cookie technology fashioned by DoubleClick, the online ad giant it acquired last year.

What's still unclear is whether Google is collecting your surfing habits across AdSense pages as well as sites that serve ads via DoubleClick's ad management platform. Presumably, it is. It appears that both AdSense and DoubleClick sites are using compatible tracking cookies.

We've asked Google (several times) to clarify the situation, but it has yet to provide an unambiguous answer. "The Google content network (AdSense partners) and DoubleClick ad management platforms have not been combined," reads a carefully worded statement from a company spokeswoman. "The Google content network uses the DoubleClick cookie to serve interest-based ads on the Google content network."

What's more, even when it comes to AdSense sites, Google's has yet to say what exactly it's collecting when you visit a site or how long that data will be kept. Presumably, it's grabbing your IP address, your browser user agent, and a time stamp as well as a specific url. DoubleClick has collected such data for years.

The concern is that Google is gradually expanding the already vast array of data it stores on each individual web surfer - data it could be coughed up after a Google hack or the arrival of a subpoena or national security letter. DoubleClick's ad serving technology is collecting surf data across third-party sites. It now appears that Google is combining this with data harvested on AdSense. And if the company ever sees fit, it could easily fold in the data collected on its juggernaut of a search engine.

According to the latest numbers from Attributor, AdSense and DoubleClick are by far the most dominant (non-search) ad platforms on the web. Together, they control 57 per cent of the market. Even if you combine Microsoft and Yahoo! - which Microsoft's chief executive Steve Ballmer once tried to do - they would reach only 15 per cent.

And in search, Google shows even more muscle, ruling more than 60 per cent of the market, according to comScore.

Google will tell you it doesn't collect any "personally identifiable information." But it refuses to acknowledge that an IP address is enough for personally identification - particularly when its paired with countless urls and time stamps.

As longtime Google Watcher Daniel Brandt points out, it would seem that Google is already collecting your surf history across both AdSense and DoubleClick. Using a network protocol analyzer, Brandt has noticed that if you visit DoubleClick site like, say, MSNBC.com and it places a DoubleClick ad cookie on your machine, that same cookie is offered up to the server when you visit an AdSense site. And vice versa.

We choose MSNBC only because it's slightly amusing to note that Microsoft is using Google ad technology.

The AdSense DoubleClick cookie does use a different prefix in the ID field than the DoubleClick DoubleClick cookie, but otherwise, the two seem identical. When we ask Google whether it's pooling data from both networks, it does not respond.

But surely, to question whether Google is collecting user data across both systems is merely questioning the obvious. "The doubleclick.net cookie is served up by your browser for both the so-called DoubleClick network that does not use AdSense, as well as the AdSense that everyone is talking about," Brandt tells us.

"They'd be crazy to harvest data from AdSense only, but not the old DoubleClick. It would take them twice as long to build up their database of user interests."

But the bigger question is what's in that database of interests - and how long it's kept. Again, Google is mum on the matter. But that's the norm.

In September, Google told the World it was "going to anonymize" its search logs after only nine months - down from the current 18. But half a year later, Google has yet to say whether thus plan has actually be put in place. And even when this nine month anonymization plan does arrive, it won't actually anonymize after nine months.

Google does let you opt out of its DoubleClick cookie. But government regulators must determine whether this cookie should be opt-in only. At the very least, Google should provide the facts needed to make an informed decision. ®