Entries Tagged "cryptography"

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Class Break of TiVoToGo DRM

Last week I wrote about the security problems of having a secret stored in a device given to your attacker, and how they are vulnerable to class breaks. I singled out DRM systems as being particularly vulnerable to this kind of security problem.

This week we have an example: The DRM in TiVoToGo has been cracked:

An open source command-line utility that converts TiVoToGo movies into an MPEG file and strips the DRM is now available online. Released under a BSD license, the utility—called TiVo File Decoder—builds on the extensive reverse engineering efforts of the TiVo hacking community. The goal of the project is to bring TiVo media viewing capabilities to unsupported platforms like OS X and the open source Linux operating system. TiVoToGo support is currently only available on Windows.

EDITED TO ADD (12/8): I have been told that TiVoTo Go has not been hacked: “The decryption engine has been reverse engineered in cross-platform code – replicating what TiVo already provides customers on the Windows platform (in the form of TiVo Desktop software). Each customer’s unique Media Access Key (MAK) is still needed as a *key* to decrypt content from their particular TiVo unit. I can’t decrypt shows from your TiVo, and you can’t decrypt shows from mine. Until someone figures out how to produce or bypass the required MAK, it hasn’t been cracked.”

And here’s a guide to installing TiVoToGo on your Mac.

EDITED TO ADD (12/17): Log of several hackers working on the problem. Interesting.

Posted on December 7, 2006 at 12:42 PM • View Comments

The Unabomber's Code

This is interesting. Ted Kaczynski wrote in code:

In a small journal written in code, he documented his thoughts about the crimes he was committing. That code was so difficult, a source says the CIA couldn’t crack it—until someone found the key itself among other documents, and then translated it.

Look at the photo. It was a manual, pencil-and-paper cipher. Does anyone know the details of the algorithm?

Posted on December 6, 2006 at 12:53 PM • View Comments

David Kahn Donates his Cryptology Library

According to The New York Times:

The National Cryptologic Museum, at Fort Meade, Md., home of thousands of code-breaking and code-making artifacts dating back to the 1500s, has acquired a major collection of books on codes and ciphers, the museum said. It was donated by David Kahn, a leading American scholar of cryptology and the author of “The Codebreakers: The Story of Secret Writing.” The collection includes “Polygraphiae Libri Sex” (1518) by Johannes Trithemius, the first known printed book on cryptology, along with notes of interviews with modern cryptologists, memos, photocopies and pamphlets. About a dozen items from the collection are currently on display.

Posted on November 24, 2006 at 7:55 AM • View Comments

New Timing Attack Against RSA

A new paper describes a timing attack against RSA, one that bypasses existing security measures against these sorts of attacks. The attack described is optimized for the Pentium 4, and is particularly suited for applications like DRM.

Meta moral: If Alice controls the device, and Bob wants to control secrets inside the device, Bob has a very difficult security problem. These “side-channel” attacks—timing, power, radiation, etc.—allow Alice to mount some very devastating attacks against Bob’s secrets.

I’m going to write more about this for Wired next week, but for now you can read the paper, the Slashdot thread, and the essay I wrote in 1998 about side-channel attacks (also this academic paper).

Posted on November 21, 2006 at 7:24 AM • View Comments

Classical Crypto with Lasers

I simply don’t have the physics background to evaluate this:

Scheuer and Yariv’s concept for key distribution involves establishing a laser oscillation between the two users, who each decide how to reflect the light at their end by choosing one of three mirrors that peak at different frequencies.

Before a key is exchanged, the users reset the system by using the first mirror. Then they both randomly select a bit (either 1 or 0) and choose the corresponding mirror out of the other two, causing the lasing properties (wavelength and intensity) to shift in accordance with the mirror they chose. Because each user knows his or her own bit, they can determine the value of each other’s bits; but an eavesdropper, who doesn’t know either bit, could only figure out the correlation between bits, but not the bits themselves. Similar to quantum key distribution systems, the bit exchange is successful in about 50% of the cases.

“For a nice analogy, consider a very large ‘justice scale’ where Alice is at one side and Bob is at the other,” said Scheuer. “Both Alice and Bob have a set of two weights (say one pound representing ‘0’ and two pounds representing ‘1’). To exchange a bit, Alice and Bob randomly select a bit and put the corresponding weight on the scales. If they pick different bits, the scales will tilt toward the heavy weight, thus indicating who picked ‘1’ and who picked ‘0.’ If however, they choose the same bit, the scales will remain balanced, regardless whether they (both) picked ‘0’ or ‘1.’ These bits can be used for the key because Eve, who in this analogy can only observe the tilt of the scales, cannot deduce the exchanged bit (in the previous case, Eve could deduce the bits). Of course, there are some differences between the laser concept and the scales analogy: in the laser system, the successful bit exchanges occur when Alice and Bob pick opposite bits, and not identical; also, there is the third state needed for resetting the laser, etc. But the underlying concept is the same: the system uses some symmetry properties to ‘calculate’ the correlation between the bits selected in each side, and it reveals only the correlation. For Alice and Bob, this is enough—but not for Eve.”

But this quote gives me pause:

Although users can’t easily detect an eavesdropper here, the system increases the difficulty of eavesdropping “almost arbitrarily,” making detecting eavesdroppers almost unnecessary.

EDITED TO ADD (11/6): Here’s the paper.

Posted on November 6, 2006 at 7:49 AM • View Comments

Bureau of Industry and Security Hacked

The BIS is the part of the U.S. Department of Commerce responsible for export control. If you have a dual-use technology that you need special approval in order to export outside the U.S., or to export it to specific countries, BIS is what you submit the paperwork to.

It’s been hacked by “hackers working through Chinese servers,” and has been shut down. This may very well have been a targeted attack.

Manufacturers of hardware crypto devices—mass-market software is exempted—must submit detailed design information to BIS in order to get an export license. There’s a lot of detailed information on crypto products in the BIS computers.

Of course, I have no way of knowing if this information was breached or if that’s what the hackers were after, but it is interesting. On the other hand, any crypto product that relied on this information being secret doesn’t deserve to be on the market anyway.

Posted on October 11, 2006 at 7:16 AM • View Comments

FairUse4WM News

A couple of weeks I ago I wrote about the battle between Microsoft’s DRM system and FairUse4WM, which breaks it. The news for this week is that Microsoft has patched their security against FairUseWM 1.2 and filed a lawsuit against the program’s anonymous authors, and those same anonymous authors have released FairUse4WM 1.3, which breaks the latest Microsoft patch.

We asked Viodentia about Redmond’s accusation that he and/or his associates broke into its systems in order to obtain the IP necessary to crack PlaysForSure; Vio replied that he’s “utterly shocked” by the charge. “I didn’t use any Microsoft source code. However, I believe that this lawsuit is a fishing expedition to get identity information, which can then be used to either bring more targeted lawsuits, or to cause other trouble.” We’re sure Microsoft would like its partners and the public to think that its DRM is generally infallible and could only be cracked by stealing its IP, so Viodentia’s conclusion about its legal tactics seems pretty fair, obvious, and logical to us.

What’s interesting about this continuing saga is how different it is from the normal find-vulnerability-then-patch sequence. The authors of FairUse4WM aren’t finding bugs and figuring out how to exploit them, forcing Microsoft to patch them. This is a sequence of crack, fix, re-crack, re-fix, etc.

The reason we’re seeing this—and this is going to be the norm for DRM systems—is that DRM is fundamentally an impossible problem. Making it work at all involves tricks, and breaking DRM is akin to “fixing” the software so the tricks don’t work. Anyone looking for a demonstation that technical DRM is doomed should watch this story unfold. (If Microsoft has any chance of winning at all, it’s via the legal route.)

Posted on September 28, 2006 at 12:55 PM • View Comments

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Sidebar photo of Bruce Schneier by Joe MacInnis.