Entries Tagged "full-disk encryption"

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Encrypting Disks

The UK is learning:

The Scottish Ambulance Service confirmed today that a package containing contact information from its Paisley Emergency Medical Dispatch Centre (EMDC) has been lost by the courier, TNT, while in transit to one of its IT suppliers.

The portable data disk contained a copy of records of 894,629 calls to the ambulance service’s Paisley EMDC since February 2006. It was fully encrypted and password protected and includes the addresses of incidents, some phone numbers and some patient names. Given the security measures and the complex structure of the database it would be extremely difficult to gain access to any meaningful information.

News story here.

That’s what you want to do. There is no problem if encrypted disks are lost. You can mail them directly to your worst enemy and there’s no problem. Well, assuming you’ve implemented the encryption properly and chosen a good key.

This is much better than what the HM Revenue & Customs office did in November.

I wrote about disk and laptop encryption previously.

Posted on July 4, 2008 at 1:10 PM • View Comments

Crossing Borders with Laptops and PDAs

Last month a US court ruled that border agents can search your laptop, or any other electronic device, when you’re entering the country. They can take your computer and download its entire contents, or keep it for several days. Customs and Border Patrol has not published any rules regarding this practice, and I and others have written a letter to Congress urging it to investigate and regulate this practice.

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.

EDITED TO ADD (5/18): Many people have pointed out to me that I advise people to lie to a government agent. That is, of course, illegal in the U.S. and probably most other countries—and probably not the best advice for me to be on record as giving. So be sure you clear your story first with both your boss and the New York office.

Posted on May 16, 2008 at 6:10 AM • View Comments

Physically Hacking Windows Computers via FireWire

This is impressive:

With Winlockpwn, the attacker connects a Linux machine to the Firewire port on the victim’s machine. The attacker then gets full read-and-write memory access and the tool deactivates Windows’s password protection that resides in local memory. Then he or she has carte blanche to steal passwords or drop rootkits and keyloggers onto the machine.

Full disk encryption seems like the only defense here.

Posted on March 13, 2008 at 11:54 AM • View Comments

Cold Boot Attacks Against Disk Encryption

Nice piece of research:

We show that disk encryption, the standard approach to protecting sensitive data on laptops, can be defeated by relatively simple methods. We demonstrate our methods by using them to defeat three popular disk encryption products: BitLocker, which comes with Windows Vista; FileVault, which comes with MacOS X; and dm-crypt, which is used with Linux.

[…]

The root of the problem lies in an unexpected property of today’s DRAM memories. DRAMs are the main memory chips used to store data while the system is running. Virtually everybody, including experts, will tell you that DRAM contents are lost when you turn off the power. But this isn’t so. Our research shows that data in DRAM actually fades out gradually over a period of seconds to minutes, enabling an attacker to read the full contents of memory by cutting power and then rebooting into a malicious operating system.

Interestingly, if you cool the DRAM chips, for example by spraying inverted cans of “canned air” dusting spray on them, the chips will retain their contents for much longer. At these temperatures (around -50 °C) you can remove the chips from the computer and let them sit on the table for ten minutes or more, without appreciable loss of data. Cool the chips in liquid nitrogen (-196 °C) and they hold their state for hours at least, without any power. Just put the chips back into a machine and you can read out their contents.

This is deadly for disk encryption products because they rely on keeping master decryption keys in DRAM. This was thought to be safe because the operating system would keep any malicious programs from accessing the keys in memory, and there was no way to get rid of the operating system without cutting power to the machine, which “everybody knew” would cause the keys to be erased.

Our results show that an attacker can cut power to the computer, then power it back up and boot a malicious operating system (from, say, a thumb drive) that copies the contents of memory. Having done that, the attacker can search through the captured memory contents, find any crypto keys that might be there, and use them to start decrypting hard disk contents. We show very effective methods for finding and extracting keys from memory, even if the contents of memory have faded somewhat (i.e., even if some bits of memory were flipped during the power-off interval). If the attacker is worried that memory will fade too quickly, he can chill the DRAM chips before cutting power.

There seems to be no easy fix for these problems. Fundamentally, disk encryption programs now have nowhere safe to store their keys. Today’s Trusted Computing hardware does not seem to help; for example, we can defeat BitLocker despite its use of a Trusted Platform Module.

The paper is here; more info is here. Articles here.

There is a general security problem illustrated here: it is very difficult to secure data when the attacker has physical control of the machine the data is stored on. I talk about the general problem here, and it’s a hard problem.

EDITED TO ADD (2/26): How-to, with pictures.

Posted on February 21, 2008 at 1:29 PM • View Comments

How to Secure Your Computer, Disks, and Portable Drives

Computer security is hard. Software, computer and network security are all ongoing battles between attacker and defender. And in many cases the attacker has an inherent advantage: He only has to find one network flaw, while the defender has to find and fix every flaw.

Cryptography is an exception. As long as you don’t write your own algorithm, secure encryption is easy. And the defender has an inherent mathematical advantage: Longer keys increase the amount of work the defender has to do linearly, while geometrically increasing the amount of work the attacker has to do.

Unfortunately, cryptography can’t solve most computer-security problems. The one problem cryptography can solve is the security of data when it’s not in use. Encrypting files, archives—even entire disks—is easy.

All of this makes it even more amazing that Her Majesty’s Revenue & Customs in the United Kingdom lost two disks with personal data on 25 million British citizens, including dates of birth, addresses, bank-account information and national insurance numbers. On the one hand, this is no bigger a deal than any of the thousands of other exposures of personal data we’ve read about in recent years—the U.S. Veteran’s Administration loss of personal data of 26 million American veterans is an obvious similar event. But this has turned into Britain’s privacy Chernobyl.

Perhaps encryption isn’t so easy after all, and some people could use a little primer. This is how I protect my laptop.

There are several whole-disk encryption products on the market. I use PGP Disk’s Whole Disk Encryption tool for two reasons. It’s easy, and I trust both the company and the developers to write it securely. (Disclosure: I’m also on PGP Corp.’s Technical Advisory Board.)

Setup only takes a few minutes. After that, the program runs in the background. Everything works like before, and the performance degradation is negligible. Just make sure you choose a secure password—PGP’s encouragement of passphrases makes this much easier—and you’re secure against leaving your laptop in the airport or having it stolen out of your hotel room.

The reason you encrypt your entire disk, and not just key files, is so you don’t have to worry about swap files, temp files, hibernation files, erased files, browser cookies or whatever. You don’t need to enforce a complex policy about which files are important enough to be encrypted. And you have an easy answer to your boss or to the press if the computer is stolen: no problem; the laptop is encrypted.

PGP Disk can also encrypt external disks, which means you can also secure that USB memory device you’ve been using to transfer data from computer to computer. When I travel, I use a portable USB drive for backup. Those devices are getting physically smaller—but larger in capacity—every year, and by encrypting I don’t have to worry about losing them.

I recommend one more complication. Whole-disk encryption means that anyone at your computer has access to everything: someone at your unattended computer, a Trojan that infected your computer and so on. To deal with these and similar threats I recommend a two-tier encryption strategy. Encrypt anything you don’t need access to regularly—archived documents, old e-mail, whatever—separately, with a different password. I like to use PGP Disk’s encrypted zip files, because it also makes secure backup easier (and lets you secure those files before you burn them on a DVD and mail them across the country), but you can also use the program’s virtual-encrypted-disk feature to create a separately encrypted volume. Both options are easy to set up and use.

There are still two scenarios you aren’t secure against, though. You’re not secure against someone snatching your laptop out of your hands as you’re typing away at the local coffee shop. And you’re not secure against the authorities telling you to decrypt your data for them.

The latter threat is becoming more real. I have long been worried that someday, at a border crossing, a customs official will open my laptop and ask me to type in my password. Of course I could refuse, but the consequences might be severe—and permanent. And some countries—the United Kingdom, Singapore, Malaysia—have passed laws giving police the authority to demand that you divulge your passwords and encryption keys.

To defend against both of these threats, minimize the amount of data on your laptop. Do you really need 10 years of old e-mails? Does everyone in the company really need to carry around the entire customer database? One of the most incredible things about the Revenue & Customs story is that a low-level government employee mailed a copy of the entire national child database to the National Audit Office in London. Did he have to? Doubtful. The best defense against data loss is to not have the data in the first place.

Failing that, you can try to convince the authorities that you don’t have the encryption key. This works better if it’s a zipped archive than the whole disk. You can argue that you’re transporting the files for your boss, or that you forgot the key long ago. Make sure the time stamp on the files matches your claim, though.

There are other encryption programs out there. If you’re a Windows Vista user, you might consider BitLocker. This program, embedded in the operating system, also encrypts the computer’s entire drive. But it only works on the C: drive, so it won’t help with external disks or USB tokens. And it can’t be used to make encrypted zip files. But it’s easy to use, and it’s free.

This essay previously appeared on Wired.com.

EDITED TO ADD (12/14): Lots of people have pointed out that the free and open-source program TrueCrypt is a good alternative to PGP Disk. I haven’t used or reviewed the program at all.

Posted on December 4, 2007 at 6:40 AM • View Comments

UK's Privacy Chernobyl

I didn’t write about this story at first because we’ve seen it so many times before: a disk with lots of personal information is lost. Encryption is the simple and obvious solution, and that’s the end of it.

But the UK’s loss of 25 million child benefit records—including dates of birth, addresses, bank account information, and national insurance numbers—is turning into a privacy disaster, threatening to derail plans for a national ID card.

Why is it such a big deal? Certainly the scope: 40% of the British population. Also the data: bank account details; plus information about children. There’s already a larger debate on the issue of a database on kids that this feeds into. And it’s a demonstration of government incompetence (think Hurricane Katrina).

In any case, this issue isn’t going away anytime soon. Prime Minister Gordon Brown has apologized. The head of the Revenue and Customs office has resigned. More is certainly coming.

And this is an easy security problem to solve! Disk and file encryption software is cheap, easy to use, and effective.

Posted on November 26, 2007 at 1:15 PM • View Comments

Seagate Encrypted Drive

Seagate has announced a product called DriveTrust, which provides hardware-based encryption on the drive itself. The technology is proprietary, but they use standard algorithms: AES and triple-DES, RSA, and SHA-1. Details on the key management are sketchy, but the system requires a pre-boot password and/or combination of biometrics to access the disk. And Seagate is working on some sort of enterprise-wide key management system to make it easier to deploy the technology company-wide.

The first target market is laptop computers. No computer manufacturer has announced support for DriveTrust yet.

More details in these articles.

Posted on November 7, 2006 at 7:04 AM • View Comments

Risks of Losing Portable Devices

Last July I blogged about the risks of storing ever-larger amounts of data in ever-smaller devices.

Last week I wrote my tenth Wired.com column on the topic:

The point is that it’s now amazingly easy to lose an enormous amount of information. Twenty years ago, someone could break into my office and copy every customer file, every piece of correspondence, everything about my professional life. Today, all he has to do is steal my computer. Or my portable backup drive. Or my small stack of DVD backups. Furthermore, he could sneak into my office and copy all this data, and I’d never know it.

This problem isn’t going away anytime soon.

There are two solutions that make sense. The first is to protect the data. Hard-disk encryption programs like PGP Disk allow you to encrypt individual files, folders or entire disk partitions. Several manufacturers market USB thumb drives with built-in encryption. Some PDA manufacturers are starting to add password protection—not as good as encryption, but at least it’s something—to their devices, and there are some aftermarket PDA encryption programs.

The second solution is to remotely delete the data if the device is lost. This is still a new idea, but I believe it will gain traction in the corporate market. If you give an employee a BlackBerry for business use, you want to be able to wipe the device’s memory if he loses it. And since the device is online all the time, it’s a pretty easy feature to add.

But until these two solutions become ubiquitous, the best option is to pay attention and erase data. Delete old e-mails from your BlackBerry, SMSs from your cell phone and old data from your address books—regularly. Find that call log and purge it once in a while. Don’t store everything on your laptop, only the files you might actually need.

EDITED TO ADD (2/2): A Dutch army officer lost a memory stick with details of an Afgan mission.

Posted on February 1, 2006 at 10:32 AM • View Comments

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Sidebar photo of Bruce Schneier by Joe MacInnis.