Posted on 08/22/2011 5:26:12 AM PDT by ShadowAce
Researchers have found a weakness in the AES algorithm. They managed to come up with a clever new attack that can recover the secret key four times easier than anticipated by experts.
In the last decade, many researchers have tested the security of the AES algorithm, but no flaws were found so far.
In 2009, some weaknesses were identified when AES was used to encrypt data under four keys that are related in a way controlled by an attacker; while this attack was interesting from a mathematical point of view, the attack is not relevant in any application scenario.
The new attack applies to all versions of AES even if it used with a single key. The attack shows that finding the key of AES is four times easier than previously believed; in other words, AES-128 is more like AES-126.
Even with the new attack, the effort to recover a key is still huge: the number of steps to find the key for AES-128 is an 8 followed by 37 zeroes.
To put this into perspective: on a trillion machines, that each could test a billion keys per second, it would take more than two billion years to recover an AES-128 key.
Note that large corporations are believed to have millions of machines, and current machines can only test 10 million keys per second.
Because of these huge complexities, the attack has no practical implications on the security of user data; however, it is the first significant flaw that has been found in the widely used AES algorithm and was confirmed by the designers.
The AES algorithm is used by hundreds of millions of users worldwide to protect internet banking, wireless communications, and the data on their hard disks. In 2000, the Rijndael algorithm, designed by the Belgian cryptographers Dr. Joan Daemen (STMicroelectronics) and Prof. Vincent Rijmen (K.U.Leuven), was selected as the winner of an open competition organized by the US NIST (National Institute for Standards and Technology).
Today AES is used in more than 1700 NIST-validated products and thousands of others; it has been standardized by NIST, ISO, and IEEE and it has been approved by the NSA for protecting secret and even top secret information.
The attack is a result of a long-term cryptanalysis project carried out by Andrey Bogdanov (K.U.Leuven, visiting Microsoft Research at the time of obtaining the results), Dmitry Khovratovich (Microsoft Research), and Christian Rechberger (ENS Paris, visiting Microsoft Research).
I don't bother with computers; I used pencil, paper and a slide rule.
Hmm—then I’ll have to find something stronger.....
If you found a serious flaw in AES (or any other encryption system commonly believed to be secure), the financial incentive to keep it secret would be enormous.
Or both
Note that large corporations are believed to have millions of machines, and current machines can only test 10 million keys per second.
So, all we need is a million times more computers than we already have, and they have to be 100 times faster than what we have now. Then all it will take is about 2 billion years to crack a single key? Dang, time to start working on a replacement for AES. I could probably get some porkus money to do that - it'd be about as useless as every other rat-hole our money has been poured down by that ...
Microsoft research has some smart people working for them.
They’ll just bump everything up to 256-bit AES—which would be just about impossible to break.
Even if the algorithm is good, there may still be flaws in the implementation. The bid example this year was crypt_blowfish - the popular open source library used in implementation for the last 13 years turns out to have been only using every 4th character of a given password when creating hashes of said password. The fix turned out to be changing a simple cast of a char (which is default a signed integer) to an unsigned integer.
The flaw was out there for 13 years and nobody noticed!
I cracked the standard by waterboarding the poor bastard who knows the key ...
It depends on the flaw itself. For a brute-force break, you are correct. However, if the flaw involves an algorithm to break it, then just upping the bits may not be enough.
And THAT is the weakness in ANY encryption.
1. If he's near you, beat the crap out of the guy with the password. OR
2. If he's at a distance, send him email phishing for it, with a sufficiently tempting hook.
Cracking AES is mathematically interesting, but the people who are actually interesting in GETTING YOUR DATA, foolish. Compared to the two simple methods above, it's silly.
Fixed it.
The problem with that approach is that in many cases, you would like to listen in on conversations without them noticing.
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