Is your username too unique?

The Telegraph reports how spammers can now target their phishing attacks by cross-correlating usernames from multiple sites...

French security academics... harvested almost 10 million usernames from Google, eBay and MySpace.

Using statistical analysis techniques they showed that it is possible, to a high degree of certainty, to track about half of internet users across the internet based on only their username. They also showed that the more unique - the more entropy it has - the username, the more likely it is that it can be linked to a real person...

The researchers argue that such targeted phishing emails would trick more people into clicking on malicious links that allow criminals to take control of computers...

Passwords, by contrast, need to be totally unique.  But with usernames, it may sometimesbe better to blend into the crowd (or at least not to use the same username at different sites).  The research team presents a site where you can test your username to see how much entropy it has.