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seraph
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 Posted: Fri Dec 22, 2006 4:56 pm Post subject:
Eternal Protection |
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AES (Advanced Encryption Standard ) gives you 3.4 x 10 to the 38th possible 128-bit keys. In comparison, the Digital Encryption Standard (DES) keys are a mere 56 bits long, which means there are approximately 7.2 x 10 to the 16th possible DES keys. Thus, there are on the order of 10 to the 21st times more possible AES 128-bit keys than DES 56-bit keys. Assuming that one could build a machine that could recover a DES key in a second, it would take that machine approximately 149 trillion years to crack a 128-bit AES key.
(To put that into perspective, the universe is believed to be less than 20 billion years old.)
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holy cow 
 http://www.apple.com/macosx/features/filevault/
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elektro80
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| Posted: Fri Dec 22, 2006 5:08 pm Post subject:
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get out
the lawn is on fire
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Kassen
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| Posted: Sat Dec 23, 2006 6:46 am Post subject:
Re: Eternal Protection |
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| seraph wrote: |
holy cow
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Indeed! That's a embarasingly simple analysis.
For one thing it asumes brute force is the only method that will be employed and that no more research will be done nor will computer improve. That's a very naive asumption. It's not like AES is broken but 149trillion years to break 128bit AES sounds like a bit much.
In this case it makes no sense AT ALL to try to brute-force 128bitAES. It would be much simpler to brute-force the password or the master password aimed at recovering lost keys. This would still be naive since a in such a cenario you'd have a lot of data (being all of the un-encrypted files) to populate a custom dictionary with for a dictionary attack.
It's certainly good enough for most home aplications, with strong passphrases it' might be good enough for small companies (asuming no terrible bugs are found matched with ready-made exploits, a pritty dubious asumpttion considdering Apple's track-record with security in recend weeks) but this isn't going to cut it for stuff that needs serious crypto. There are good reasons why some people use 256bit.
If you realy need security that needs to last for trillions of years I'd take a stronger algorithem and at the very least I'd go with something more mature and open source.
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BobTheDog
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| Posted: Sun Dec 24, 2006 12:58 am Post subject:
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We just have to wait for quantum computers, when they get these to work this sort of problem is easily solved.
Cheers
Andy |
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Kassen
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| Posted: Sun Dec 24, 2006 2:49 am Post subject:
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| BobTheDog wrote: | We just have to wait for quantum computers, when they get these to work this sort of problem is easily solved.
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I don't think anything will ever be easily solved in strong crypto 
Take a good, long passphrase and you should be fine against most oponents.
If you have serious enemies and/or serious secrets then I wouldn't take a proprietary closed source implementation since you don't know wether you can trust Apple.
I poked around a little and found some weird things; It turns out the filevault passwords are identical to the user passwords so strong userpasswords will become very important indeed. Another silly thing is that Apple provides the option to have hint question for recovering the master password. to put it mildly; that's not such a good idea.
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seraph
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| Posted: Sun Dec 24, 2006 7:57 am Post subject:
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| Kassen wrote: | | Another silly thing is that Apple provides the option to have hint question for recovering the master password. to put it mildly; that's not such a good idea. |
maybe it's the so called "placebo effect" 
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BobTheDog
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| Posted: Tue Dec 26, 2006 1:42 am Post subject:
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| Kassen wrote: | | BobTheDog wrote: | We just have to wait for quantum computers, when they get these to work this sort of problem is easily solved.
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I don't think anything will ever be easily solved in strong crypto
Take a good, long passphrase and you should be fine against most oponents.
If you have serious enemies and/or serious secrets then I wouldn't take a proprietary closed source implementation since you don't know wether you can trust Apple.
I poked around a little and found some weird things; It turns out the filevault passwords are identical to the user passwords so strong userpasswords will become very important indeed. Another silly thing is that Apple provides the option to have hint question for recovering the master password. to put it mildly; that's not such a good idea. |
Hi Kassen,
The killer app for Quantum Computing is the fact that all know cryptography can be easily broken, this is why significant funds backing this line of research have come from the U.S. Department of defence, the National Security Agency. NATO ane the EU. They want this technology before anyone else.
In 1994 Peter Shor who worked at AT&Ts Bell Labs discovered how a Quantum Computer could calculate the factors of very large numbers extremely rapidly, this is what you need to break these kinds of code.
Lets take a 250-digit (not bit) number key that is the product of two large primes. Even with todays supercomputers it is unlikely that they will ever be able to solve the problem, with the fastest known algorithm it would take longer than the age of the universe but a quantum computer running Shors algorithm would take seconds or minutes to solve this problem as it can compute simultaneously along as many at 10 to the power of 500 different pathways.
Another interesting thing about Shaws algorithm is that increasing the size of the key does not really affect the time required to find the factors, so basically if they ever get this thing working all current cryptography will be broken.
I can recomend a book about Quantum computing which covers areas like this :
Julian Brown - Minds, Machines, and the Multiverse. ISBN 0-684-81481-1
It is very interesting and a fairly easy read with very little mathmatics.
Cheers
Andy |
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Kassen
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| Posted: Sun Dec 31, 2006 10:39 am Post subject:
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Thanks, very interesting!
I'm sorry if I was unclear, what I actually meant that wouldn't be easy is having crypto that we're sure will last trilions of years.
I kinda asumed quanti\um computers (once we get them....) will greatly help breaking current stuff but that doesn't realy tell us what to do when we need something unbreakable.
There's something "Manhatan Project-like" about this; if I get a quantum computer to encrypt things I have to asume you'll soon have one to decrypt it.... I read some interesting notes on using quantum processes for key generation and exhange too but a lot of the same problems remain. That's what I meant isn't easy; I'll take your word for decrypting current stuff being easy with one of those, I hadn't realised it'd be *that* easy.
In the end I think this is a nice feature for a OS to have but all things considered I think it'd be best to (also) rely on keeping your laptop in sight or your house locked up well. If the NSA/CIA confiscates your hard-drive all bets are off anyway.
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