Entries Tagged "encryption"

Page 47 of 56

KeeLoq Still Broken

That’s the key entry system used by Chrysler, Daewoo, Fiat, General Motors, Honda, Toyota, Lexus, Volvo, Volkswagen, Jaguar, and probably others. It’s broken:

The KeeLoq encryption algorithm is widely used for security relevant applications, e.g., in the form of passive Radio Frequency Identification (RFID) transponders for car immobilizers and in various access control and Remote Keyless Entry (RKE) systems, e.g., for opening car doors and garage doors.

We present the first successful DPA (Differential Power Analysis) attacks on numerous commercially available products employing KeeLoq. These so-called side-channel attacks are based on measuring and evaluating the power consumption of a KeeLoq device during its operation. Using our techniques, an attacker can reveal not only the secret key of remote controls in less than one hour, but also the manufacturer key of the corresponding receivers in less than one day. Knowing the manufacturer key allows for creating an arbitrary number of valid new keys and generating new remote controls.

We further propose a new eavesdropping attack for which monitoring of two ciphertexts, sent from a remote control employing KeeLoq code hopping (car key, garage door opener, etc.), is sufficient to recover the device key of the remote control. Hence, using the methods described by us, an attacker can clone a remote control from a distance and gain access to a target that is protected by the claimed to be “highly secure” KeeLoq algorithm.

We consider our attacks to be of serious practical interest, as commercial KeeLoq access control systems can be overcome with modest effort.

I’ve written about this before, but the above link has much better data.

EDITED TO ADD (4/4): A good article.

Posted on April 4, 2008 at 6:03 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

Cryptanalysis of A5/1

There have been a lot of articles about the new attack against the GSM cell phone encryption algorithm, A5/1. In some ways, this isn’t real news; we’ve seen A5/1 cryptanalysis papers as far back as ten years ago.

What’s new about this attack is: 1) it’s completely passive, 2) its total hardware cost is around $1,000, and 3) the total time to break the key is about 30 minutes. That’s impressive.

The cryptanalysis of A5/1 demonstrates an important cryptographic maxim: attacks always get better; they never get worse. This is why we tend to abandon algorithms at the first sign of weakness; we know that with time, the weaknesses will be exploited more effectively to yield better and faster attacks.

Posted on February 22, 2008 at 6:31 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

Mujahideen Secrets 2

Mujahideen Secrets 2 is a new version of an encryption tool, ostensibly written to help Al Qaeda members encrypt secrets as they communicate on the Internet.

A bunch of sites have covered this story, and a couple of security researchers are quoted in the various articles. But quotes like this make you wonder if they have any idea what they’re talking about:

Mujahideen Secrets 2 is a very compelling piece of software, from an encryption perspective, according to Henry. He said the new tool is easy to use and provides 2,048-bit encryption, an improvement over the 256-bit AES encryption supported in the original version.

No one has explained why a terrorist would use this instead of PGP—perhaps they simply don’t trust anything coming from a U.S. company. But honestly, this isn’t a big deal at all: strong encryption software has been around for over fifteen years now, either cheap or free. And the NSA probably breaks most of the stuff by guessing the password, anyway. Unless the whole program is an NSA plant, that is.

My question: the articles claim that the program uses several encryption algorithms, including RSA and AES. Does it use Blowfish or Twofish?

Posted on February 8, 2008 at 5:39 AM • View Comments

Swedish Army Loses Classified Information on Memory Stick

Oops:

The daily newspaper, Aftonbladet, turned the stick over to the Armed Forces on Thursday. The paper’s editorial office obtained the memory stick from an individual who discovered it in a public computer center in Stockholm.

An employee of the Armed Forces has reported that the misplaced USB memory stick belongs to him. The employee contacted his superior on Friday and divulged that he had forgotten the memory stick in a public computer. A preliminary technical investigation confirms that the stick belongs to the employee.

The stick contained both unclassified and classified information such as information regarding IED and mine threats in Afghanistan.

I wrote about this sort of thing two years ago:

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.

Also this. Although why the Swedish Army doesn’t encrypt its portable storage devices is beyond me.

Posted on January 9, 2008 at 1:46 PM • View Comments

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Sidebar photo of Bruce Schneier by Joe MacInnis.