Entries Tagged "encryption"

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Eavesdropping on Encrypted Compressed Voice

Traffic analysis works even through the encryption:

The new compression technique, called variable bitrate compression produces different size packets of data for different sounds.

That happens because the sampling rate is kept high for long complex sounds like “ow”, but cut down for simple consonants like “c”. This variable method saves on bandwidth, while maintaining sound quality.

VoIP streams are encrypted to prevent eavesdropping. However, a team from John Hopkins University in Baltimore, Maryland, US, has shown that simply measuring the size of packets without decoding them can identify whole words and phrases with a high rate of accuracy.

The technique isn’t good enough to decode entire conversations, but it’s pretty impressive.

Posted on June 19, 2008 at 6:27 AMView Comments

Ransomware

I’ve never figured out the fuss over ransomware:

Some day soon, you may go in and turn on your Windows PC and find your most valuable files locked up tighter than Fort Knox.

You’ll also see this message appear on your screen:

“Your files are encrypted with RSA-1024 algorithm. To recovery your files you need to buy our decryptor. To buy decrypting tool contact us at: ********@yahoo.com”

How is this any worse than the old hacker viruses that put a funny message on your screen and erased your hard drive?

Here’s how I see it, if someone actually manages to pull this up and put it into circulation, we’re looking at malware Armegeddon. Instead of losing ‘just’ your credit card numbers or having your PC turned into a spam factory, you could lose vital files forever.

Of course, you could keep current back-ups. I do, but I’ve been around this track way too many times to think that many companies, much less individual users, actually keep real back-ups. Oh, you may think you do, but when was the last time you checked to see if the data you saved could actually be restored?

The single most important thing any company or individual can do to improve security is have a good backup strategy. It’s been true for decades, and it’s still true today.

Posted on June 16, 2008 at 1:09 PMView Comments

Kaspersky Labs Trying to Crack 1024-bit RSA

I can’t figure this story out. Kaspersky Lab is launching an international distributed effort to crack a 1024-bit RSA key used by the Gpcode Virus. From their website:

We estimate it would take around 15 million modern computers, running for about a year, to crack such a key.

What are they smoking at Kaspersky? We’ve never factored a 1024-bit number—at least, not outside any secret government agency—and it’s likely to require a lot more than 15 million computer years of work. The current factoring record is a 1023-bit number, but it was a special number that’s easier to factor than a product-of-two-primes number used in RSA. Breaking that Gpcode key will take a lot more mathematical prowess than you can reasonably expect to find by asking nicely on the Internet. You’ve got to understand the current best mathematical and computational optimizations of the Number Field Sieve, and cleverly distribute the parts that can be distributed. You can’t just post the products and hope for the best.

Is this just a way for Kaspersky to generate itself some nice press, or are they confused in Moscow?

EDITED TO ADD (6/15): Kaspersky <a href=http://www.securityfocus.com/news/11523″>now says:

The company clarified, however, that it’s more interested in getting help in finding flaws in the encryption implementation.

“We are not trying to crack the key,” Roel Schouwenberg, senior antivirus researcher with Kaspersky Lab, told SecurityFocus. “We want to see collectively whether there are implementation errors, so we can do what we did with previous versions and find a mistake to help us find the key.”

Schouwenberg agrees that, if no implementation flaw is found, searching for the decryption key using brute-force computing power is unlikely to work.

“Clarified” is overly kind. There was nothing confusing about Kaspersky’s post that needed clarification, and what they’re saying now completely contradicts what they did post. Seems to me like they’re trying to pretend it never happened.

EDITED TO ADD (6/30): A Kaspersky virus analyst comments on this entry.

Posted on June 12, 2008 at 12:30 PMView Comments

E-Mail After the Rapture

It’s easy to laugh at the You’ve Been Left Behind site, which purports to send automatic e-mails to your friends after the Rapture:

The unsaved will be ‘left behind’ on earth to go through the “tribulation period” after the “Rapture”…. We have made it possible for you to send them a letter of love and a plea to receive Christ one last time. You will also be able to give them some help in living out their remaining time. In the encrypted portion of your account you can give them access to your banking, brokerage, hidden valuables, and powers of attorneys’ (you won’t be needing them any more, and the gift will drive home the message of love). There won’t be any bodies, so probate court will take 7 years to clear your assets to your next of Kin. 7 years of course is all the time that will be left. So, basically the Government of the AntiChrist gets your stuff, unless you make it available in another way.

But what if the creator of this site isn’t as scrupulous as he implies he is? What if he uses all of that account information, passwords, safe combinations, and whatever before any rapture? And even if he is an honest true believer, this seems like a mighty juicy target for any would-be identity thief.

And—if you’re curious—this is how the triggering mechanism works:

We have set up a system to send documents by the email, to the addresses you provide, 6 days after the “Rapture” of the Church. This occurs when 3 of our 5 team members scattered around the U.S fail to log in over a 3 day period. Another 3 days are given to fail safe any false triggering of the system.

The site claims that the data can be encrypted, but it looks like the encryption key is stored on the server with the data.

EDITED TO ADD (6/14): Here’s a similar site, run by atheists so they can guarantee that they’ll be left behind to deliver all the messages.

Posted on June 2, 2008 at 1:09 PMView Comments

TPM to End Piracy

Ha ha ha ha. Famous last words from Atari founder Nolan Bushnell:

“There is a stealth encryption chip called a TPM that is going on the motherboards of most of the computers that are coming out now,” he pointed out

“What that says is that in the games business we will be able to encrypt with an absolutely verifiable private key in the encryption world—which is uncrackable by people on the internet and by giving away passwords—which will allow for a huge market to develop in some of the areas where piracy has been a real problem.”

“TPM” stands for “Trusted Platform Module.” It’s a chip that is probably already in your computer and may someday be used to enforce security: both your security, and the security of software and media companies against you. The system is complicated, and while it will prevent some attacks, there are lots of ways to hack it. (I’ve written about TPM here, and here when Microsoft called it Palladium. Ross Anderson has some good stuff here.)

Posted on May 29, 2008 at 6:33 AMView Comments

BlackBerry Giving Encryption Keys to Indian Government

RIM encrypts e-mail between BlackBerry devices and the server the server with 256-bit AES encryption. The Indian government doesn’t like this at all; they want to snoop on the data. RIM’s response was basically: That’s not possible. The Indian government’s counter was: Then we’ll ban BlackBerries. After months of threats, it looks like RIM is giving in to Indian demands and handing over the encryption keys.

EDITED TO ADD (5/27): News:

BlackBerry vendor Research-In-Motion (RIM) said it cannot hand over the message encrytion key to the government as its security structure does not allow any ‘third party’ or even the company to read the information transferred over its network.

EDITED TO ADD (7/2): Looks like they have resolved the impasse.

Posted on May 21, 2008 at 2:09 PMView 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 AMView Comments

The Doghouse: Passwordsafe.com

This isn’t my Password Safe. This is PasswordSafe.com. Password Safe is an open-source application that lives on your computer and encrypts your passwords. PasswordSafe.com lets you store your passwords on their server. They promise not to look at them.

Can I trust PasswordSafe?

As we mentioned, pretty much every function is automated, no-one here ever sees your information as it’s all taken care of by the programs and encrypted into the database. Again we’ll remind you, we do not recommend you store sensitive information at PasswordSafe. In house, we’ve used this service for many sites, banner programs, affiliate programs, free email services and much more.

Posted on May 5, 2008 at 6:37 AMView Comments

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Sidebar photo of Bruce Schneier by Joe MacInnis.