Entries Tagged "cryptography"

Page 42 of 55

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 AM • View 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 PM • View 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 PM • View Comments

Random Number Bug in Debian Linux

This is a big deal:

On May 13th, 2008 the Debian project announced that Luciano Bello found an interesting vulnerability in the OpenSSL package they were distributing. The bug in question was caused by the removal of the following line of code from md_rand.c

	MD_Update(&m,buf,j);
	[ .. ]
	MD_Update(&m,buf,j); /* purify complains */

These lines were removed because they caused the Valgrind and Purify tools to produce warnings about the use of uninitialized data in any code that was linked to OpenSSL. You can see one such report to the OpenSSL team here. Removing this code has the side effect of crippling the seeding process for the OpenSSL PRNG. Instead of mixing in random data for the initial seed, the only “random” value that was used was the current process ID. On the Linux platform, the default maximum process ID is 32,768, resulting in a very small number of seed values being used for all PRNG operations.

More info, from Debian, here. And from the hacker community here. Seems that the bug was introduced in September 2006.

More analysis here. And a cartoon.

Random numbers are used everywhere in cryptography, for both short- and long-term security. And, as we’ve seen here, security flaws in random number generators are really easy to accidently create and really hard to discover after the fact. Back when the NSA was routinely weakening commercial cryptography, their favorite technique was reducing the entropy of the random number generator.

Posted on May 19, 2008 at 6:07 AM • View Comments

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

Martin Hellman on the Invention of Public-Key Cryptography

At the DISI conference last December, Martin Hellman gave a lecture on the invention of public-key cryptography. A video is online (it’s hard to find, search for his name), along with PowerPoint slides.

(Unfortunately, the video isn’t set up for streaming; in order to view the it, you’ll have to download the ten files, then use a fairly recent version of WinZip to concatenate the files.)

EDITED TO ADD (3/26): Now on Google Video.

Posted on March 25, 2008 at 1:21 PM • View Comments

1 … 40 41 42 43 44 … 55

Sidebar photo of Bruce Schneier by Joe MacInnis.