Over at Wired's Gadget Labs blog, Brian Chen writes about information discovered during a webcast presentation on Thursday covering the recently discussed iPhone security weaknesses having to do with bypassing the password-protected lock screen.

Jonathan Zdziarski, a data forensics expert and author of the forthcoming book "iPhone Forensics," did the presentation for law enforcement personnel and anyone else who might have a need to access an iPhone to discover information. During the presentation, in which he outlines a method for breaking into the phone with modified firmware and some hairy manipulation, he also showed how the iPhone takes a screenshot of every application the iPhone's user closes by pressing the "home" button. The saved image is used to "draw" the collapsing screen animation you see when your application closes and you're returned to the home screen. The image file is then deleted from the iPhone's storage.

But, nothing is ever really completely "deleted." And in this case, apparently when the temporary image file is killed from storage, the data "on-disk" is not overwritten or otherwise cleaned, so anyone with some basic forensics knowledge can search the iPhone storage space for the old files and recover them easily. You can do the same thing on pretty much any computer.

Depending on your point of view, this is either a potential privacy issue or a great forensics feature. Having worked as both a police officer and as a business security professional responsible for privacy and data integrity issues, I can understand both arguments. Certainly as a cop, being able to dig into someone's iPhone (with a proper warrant of course) to find evidence of crimes where the phone was used in some manner is of real value, and screen shots are potentially pretty useful evidence. But as a person who also values privacy as a matter of basic principle, it's a little disconcerting, especially since I didn't realize until today screen shots are being made.

The webcast recording is not yet available as of the time of this writing, but it should be posted to http://www.youtube.com/OreillyMedia in the next few days. If you're interested in learning something about electronic data forensics, it will be worth the time to check it out. Here's the O'Reilly abstract from the session:

In this free, live webcast, iPhone hacker and data forensics expert Jonathan Zdziarski guides you through the steps used by law enforcement agencies to bypass the iPhone 3G's passcode lock by creating a custom firmware bundle. Author of the upcoming book, iPhone Forensics, Jonathan has devoted much of his talent supporting law enforcement personnel with his development of a forensics toolkit that allows them to recover, process, and remove sensitive data stored on the iPhone, iPhone 3G, and iPod Touch. This live presentation is aimed towards law enforcement and anyone else who has a need to access the not-so-readily available data on an iPhone.