Telesign, creators of voice-based authentication software, was so confident of its StrongWebMail.com webmail site, recently launched, that it set up a prize fund of $10,000 for anyone able to break into it successfully.

Only a week later, a group of security researchers claim to have won. The challenge was to hack into the mail account of CEO Darren Berkovitz and report the details of his 26 June diary entry. Berkowitz acknowledged that the details provided by the researchers were correct.

However, he hasn't yet confirmed that the hackers have won the prize. He said he'd need to check that contest rules were abided by, saying: "if someone did it, we'll kind of put our heads down".

The rules mean that the researchers aren't allowed to say how they did it, but successfully compromised another account run by IDG News Service on a machine running Windows XP and Firefox.

Webmail security has proved weak in the past. During the 2008 presidential election in the United States, Alaska governor Sarah Palin's email was broken into. A college student has been charged for that incident.