Entries Tagged "cryptanalysis"

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Eavesdropping on Smart Homes with Distributed Wireless Sensors

“Protecting your daily in-home activity information from a wireless snooping attack,” by Vijay Srinivasan, John Stankovic, and Kamin Whitehouse:

Abstract: In this paper, we first present a new privacy leak in residential wireless ubiquitous computing systems, and then we propose guidelines for designing future systems to prevent this problem. We show that we can observe private activities in the home such as cooking, showering, toileting, and sleeping by eavesdropping on the wireless transmissions of sensors in a home, even when all of the transmissions are encrypted. We call this the Fingerprint and Timing-based Snooping (FATS) attack. This attack can already be carried out on millions of homes today, and may become more important as ubiquitous computing environments such as smart homes and assisted living facilities become more prevalent. In this paper, we demonstrate and evaluate the FATS attack on eight different homes containing wireless sensors. We also propose and evaluate a set of privacy preserving design guidelines for future wireless ubiquitous systems and show how these guidelines can be used in a hybrid fashion to prevent against the FATS attack with low implementation costs.

The group was able to infer surprisingly detailed activity information about the residents, including when they were home or away, when they were awake or sleeping, and when they were performing activities such as showering or cooking. They were able to infer all this without any knowledge of the location, semantics, or source identifier of the wireless sensors, while assuming perfect encryption of the data and source identifiers.

Posted on August 31, 2010 at 12:39 PM • View Comments

WPA Cracking in the Cloud

It’s a service:

The mechanism used involves captured network traffic, which is uploaded to the WPA Cracker service and subjected to an intensive brute force cracking effort. As advertised on the site, what would be a five-day task on a dual-core PC is reduced to a job of about twenty minutes on average. For the more “premium” price of $35, you can get the job done in about half the time. Because it is a dictionary attack using a predefined 135-million-word list, there is no guarantee that you will crack the WPA key, but such an extensive dictionary attack should be sufficient for any but the most specialized penetration testing purposes.

[…]

It gets even better. If you try the standard 135-million-word dictionary and do not crack the WPA encryption on your target network, there is an extended dictionary that contains an additional 284 million words. In short, serious brute force wireless network encryption cracking has become a retail commodity.

FAQ here.

In related news, there might be a man-in-the-middle attack possible against the WPA2 protocol. Man-in-the-middle attacks are potentially serious, but it depends on the details—and they’re not available yet.

EDITED TO ADD (8/8): Details about the MITM attack.

Posted on July 27, 2010 at 6:43 AM • View Comments

Cryptanalysis of the DECT

New cryptanalysis of the proprietrary encryption algorithm used in the Digital Enhanced Cordless Telecommunications (DECT) standard for cordless phones.

Abstract. The DECT Standard Cipher (DSC) is a proprietary 64-bit stream cipher based on irregularly clocked LFSRs and a non-linear output combiner. The cipher is meant to provide confidentiality for cordless telephony. This paper illustrates how the DSC was reverse-engineered from a hardware implementation using custom firmware and information on the structure of the cipher gathered from a patent. Beyond disclosing the DSC, the paper proposes a practical attack against DSC that recovers the secret key from 215 keystreams on a standard PC with a success rate of 50% within hours; somewhat faster when a CUDA graphics adapter is available.

News.

Posted on April 8, 2010 at 1:05 PM • View Comments

Cryptography Broken on American Military Attack Video

Any ideas?

At a news conference at the National Press Club, WikiLeaks said it had acquired the video from whistle-blowers in the military and viewed it after breaking the encryption code. WikiLeaks released the full 38-minute video as well as a 17-minute edited version.

And this quote from the WikiLeaks Twitter feed on Feb 20th:

Finally cracked the encryption to US military video in which journalists, among others, are shot. Thanks to all who donated $/CPUs.

Surely this isn’t NSA-level encryption. But what is it?

Note that this is intended to be a discussion about the cryptanalysis, not about the geopolitics of the event.

EDITED TO ADD (4/13): It was a dictionary attack.

Posted on April 7, 2010 at 1:37 PM • View Comments

New Attack on Threefish

At FSE 2010 this week, Dmitry Khovratovich and Ivica Nikolic presented a paper where they cryptanalyze ARX algorithms (algorithms that use only addition, rotation, and exclusive-OR operations): “Rotational Cryptanalysis of ARX.” In the paper, they demonstrate their attack against Threefish. Their attack breaks 39 (out of 72) rounds of Threefish-256 with a complexity of 2252.4, 42 (out of 72) rounds of Threefish-512 with a complexity of 2507, and 43.5 (out of 80) rounds of Threefish-1024 with a complexity of 21014.5. (Yes, that’s over 21000. Don’t laugh; it really is a valid attack, even though it—or any of these others—will never be practical.)

This is excellent work, and represents the best attacks against Threefish to date. (I suspect that the attacks can be extended a few more rounds with some clever cryptanalytic tricks, but no further.) The security of full Threefish isn’t at risk, of course; there’s still plenty of security margin.

We have always stood by the security of Threefish with any set of non-obviously-bad constants. Still, a trivial modification—changing a single constant in the key schedule—dramatically reduces the number of rounds through which this attack can penetrate. If NIST allows another round of tweaks to the SHA-3 candidate algorithms, we will almost certainly take the opportunity to improve Skein’s security; we’ll change this constant to a value that removes the rotational symmetries that this technique exploits. If they don’t, we’re still confident of the security of Threefish and Skein.

And we’re always pleased to see more cryptanalysis against Threefish and Skein.

Posted on February 7, 2010 at 8:06 AM • View Comments

768-bit Number Factored

News:

On December 12, 2009, we factored the 768-bit, 232-digit number RSA-768 by the number field sieve. The number RSA-768 was taken from the now obsolete RSA Challenge list as a representative 768-bit RSA modulus. This result is a record for factoring general integers. Factoring a 1024-bit RSA modulus would be about a thousand times harder, and a 768-bit RSA modulus is several thousands times harder to factor than a 512-bit one. Because the first factorization of a 512-bit RSA modulus was reported only a decade ago it is not unreasonable to expect that 1024-bit RSA moduli can be factored well within the next decade by an academic effort such as ours…. Thus, it would be prudent to phase out usage of 1024-bit RSA within the next three to four years.

[…]

Our computation required more than 1020 operations. With the equivalent of almost 2000 years of computing on a single core 2.2GHz AMD Opteron, on the order of 267 instructions were carried out. The overall effort is sufficiently low that even for short-term protection of data of little value, 768-bit RSA moduli can no longer be recommended.

News articles.

Posted on January 11, 2010 at 8:00 AM • View Comments

Quantum Cryptography Cracked

Impressive:

This presentation will show the first experimental implementation of an eavesdropper for quantum cryptosystem. Although quantum cryptography has been proven unconditionally secure, by exploiting physical imperfections (detector vulnerability) we have successfully built an intercept-resend attack and demonstrated eavesdropping under realistic conditions on an installed quantum key distribution line. The actual eavesdropping hardware we have built will be shown during the conference.

While I am very interested in quantum cryptography, I have never been optimistic about its practicality. And it’s always interesting to see provably secure cryptosystems broken.

Posted on December 30, 2009 at 6:04 AM • View Comments

Al Qaeda Secret Code Broken

I would sure like to know more about this:

Top code-breakers at the Government Communications Headquarters in the United Kingdom have succeeded in breaking the secret language that has allowed imprisoned leaders of al-Qaida to keep in touch with other extremists in U.K. jails as well as 10,000 “sleeper agents” across the islands….

[…]

For six months, the code-breakers worked around the clock deciphering the code the three terrorists created.

Between them, the code-breakers speak all the dialects that form the basis for the code. Several of them have high-value skills in computer technology. The team worked closely with the U.S. National Security Agency and its station at Menwith Hill in the north of England. The identity of the code-breakers is so secret that not even their gender can be revealed.

“Like all good codes, the one they broke depended on substituting words, numbers or symbols for plain text. A single symbol could represent an idea or an entire message,” said an intelligence source.

The code the terrorists devised consists of words chosen from no fewer than 20 dialects from Afghanistan, Iran, Pakistan, Yemen and Sudan.

Inserted with the words ­ either before or after them ­ is local slang. The completed message is then buried in Islamic religious tracts.

EDITED TO ADD: Here’s a link to the story that still works. I didn’t realize this came from WorldNetDaily, so take it with an appropriate amount of salt.

Posted on November 23, 2009 at 7:24 AM • View Comments

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Sidebar photo of Bruce Schneier by Joe MacInnis.