I once was working on a project to install a robust wireless network for a company.  I asked the guy I was working with why they were doing it. This company had a general attitude of paranoia where security was concerned, so the drive to fast-track an expensive wireless network seemed out of place.  It turns out, this company’s president had been playing golf with the president of another company.  The president of the other company started bragging about his company’s new wireless network and how he could take his laptop anywhere in the building and get on the network.  Embarrassed, the president came back to work and immediately told his IT staff to install a WLAN so that he would never again suffer such indignation.  Halfway through the project, cooler heads pointed out to the president that since his company focused on critical infrastructure, the security risks of wireless were too great for them to bear.   

This new push for mobility has created a hierarchy within companies.  The important people get the coolest phones and PDAs.  I once discovered a disturbing trend during a policy review related to mobile devices:  when a new phone or PDA came out, a rash of dropped, damaged, and broken phones were turned into the person in charge of handing out mobile devices.  Many "accidentally" fell into the toilet.  Real money was being lost here, as employees jockeyed for status brought by the flashiest new phones.  Yes, this does really happen. I guess I shouldn’t have been shocked by this.  The mobile phone folks figured it out long ago…

Nowhere is that shift clearer than at the FBI's Regional Forensic Computer Lab here, which once lifted traces of incriminating Google searches from a suspect's hard drive to help convict him of murder. This week the lab became the sixth computer forensic lab in the nation to be accredited by the American Society of Crime Laboratory Directors, in another sign that computer forensics is no longer just about investigating hacker attacks.

"We've found video of gangsters rapping a song about a murder they committed," RCFL examiner John Leamons says.

The growth of law enforcement computer labs is an indication of how technology is increasingly involved in, or on the periphery of, criminal activity. San Diego-area law enforcement agencies founded the first regional forensic lab in 1998; there are now 14 such labs in the United States, with two more coming online this year. Last year the labs collectively performed more than 13,000 forensics examinations. The San Diego lab alone handled more than 1,000 requests from 40 law enforcement agencies in 2007, including 171 child pornography cases and 160 murder investigations.

In its early days, the RFCL examiners not only recovered the data, they analyzed it for evidentiary value based on the particulars of the case. But with exponentially growing data and caseloads, the 22 examiners here now focus on collecting and preserving data in a manner that will hold up in court, then hand that data back to the police agency for analysis.

Not surprisingly, the most valuable information comes from the files that suspects thought they had deleted, but which remained hidden in the nooks and crannies of their hard drives. "The key to computer forensics is unallocated space," says Leamons, who is on loan to the lab from the San Diego Police Department.

No one can remember a case being kicked because the lab made an error, but they can remember cases where they found evidence that exonerated people charged with crimes, Leamons says.

Cellphones pose a particular challenge, says Rebecca Adimari, one of the five examiners who work on them.

"Each has its own operating system and frequency -- there's probably over 500 makes and models and not many of them are the same," she explains. "There can be so much evidence on there."

From the unique ringtone caught on camera during a holdup -- to the accidentally recorded conversations on voice notes, to the Israeli thug keeping notes of extortion visits on his PDA -- the way people use their phones can be pretty incriminating.

"When they arrested the Arellano Felix people (a gang of Mexican drug lords later convicted of murder and drug crimes in 2007), they recovered 14 phones including one with a photo of a machine gun," Adimari says.

She has hundreds of power and data cables, since they're all peculiar to individual phones. And she has a special box that blocks signals on the phones in the lab, so no information is lost or compromised.

Examiner Patrick Lim, from the Naval Criminal Investigative Services, says he recently recovered data from a hard drive that had been burnt to a crisp. Asked if it was from an arson or a murder, Lim says he can't reveal the details.

"It was burned. That's all I can say."

But the US is not alone. British customs agents search laptops for pornography. And there are reports on the internet of this sort of thing happening at other borders, too. You might not like it, but it's a fact. So how do you protect yourself?

Encrypting your entire hard drive, something you should certainly do for security in case your computer is lost or stolen, won't work here. The border agent is likely to start this whole process with a "please type in your password". Of course you can refuse, but the agent can search you further, detain you longer, refuse you entry into the country and otherwise ruin your day.

You're going to have to hide your data. Set a portion of your hard drive to be encrypted with a different key - even if you also encrypt your entire hard drive - and keep your sensitive data there. Lots of programs allow you to do this. I use PGP Disk . TrueCrypt is also good, and free.

While customs agents might poke around on your laptop, they're unlikely to find the encrypted partition. (You can make the icon invisible, for some added protection.) And if they download the contents of your hard drive to examine later, you won't care.

Be sure to choose a strong encryption password. Details are too complicated for a quick tip, but basically anything easy to remember is easy to guess. (My advice is here.) Unfortunately, this isn't a perfect solution. Your computer might have left a copy of the password on the disk somewhere, and (as I also describe at the above link) smart forensic software will find it.

So your best defence is to clean up your laptop. A customs agent can't read what you don't have. You don't need five years' worth of email and client data. You don't need your old love letters and those photos (you know the ones I'm talking about). Delete everything you don't absolutely need. And use a secure file erasure program to do it. While you're at it, delete your browser's cookies, cache and browsing history. It's nobody's business what websites you've visited. And turn your computer off - don't just put it to sleep - before you go through customs; that deletes other things. Think of all this as the last thing to do before you stow your electronic devices for landing. Some companies now give their employees forensically clean laptops for travel, and have them download any sensitive data over a virtual private network once they've entered the country. They send any work back the same way, and delete everything again before crossing the border to go home. This is a good idea if you can do it.

If you can't, consider putting your sensitive data on a USB drive or even a camera memory card: even 16GB cards are reasonably priced these days. Encrypt it, of course, because it's easy to lose something that small. Slip it in your pocket, and it's likely to remain unnoticed even if the customs agent pokes through your laptop. If someone does discover it, you can try saying: "I don't know what's on there. My boss told me to give it to the head of the New York office." If you've chosen a strong encryption password, you won't care if he confiscates it.

Lastly, don't forget your phone and PDA. Customs agents can search those too: emails, your phone book, your calendar. Unfortunately, there's nothing you can do here except delete things.

I know this all sounds like work, and that it's easier to just ignore everything here and hope you don't get searched. Today, the odds are in your favour. But new forensic tools are making automatic searches easier and easier, and the recent US court ruling is likely to embolden other countries. It's better to be safe than sorry.

This essay originally appeared in The Guardian.

Some other advice here.

Biometric data is generally regarded as being ill-suited for cryptography: each measurement, even when taken by the same device, of the same feature on the same person will differ slightly. This noise in the data makes it difficult to extract a cryptographic key in the traditional sense. Other recent work has shown that it’s possible to use just the noise in a biometric measurement to generate a cryptographic key—the new method relies on this principle.

Researchers put together a system that can be implemented on any device equipped with a camera. Facial recognition software is then used to produce biometric measurements of a person’s face, which should stay constant through changes in hairstyle, makeup, etc. Users take a picture of themselves, then uses a random string that, combined with the biometric information, forms the equivalent of a public key.

When two people need to establish a connection between their devices, they exchange these public keys, and each then takes a picture of the other device’s owner. The biometric data from this new picture is used to try to extract the random string from the public key.

It sounds a little like social networking in the cryptography world — and a bit hairier than just using a password. Do you think it’s a good idea?

Read the full article here.