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How secure is AES against brute force attacks?

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David Brown
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re: How secure is AES against brute force attacks?
David Brown   5/21/2013 7:12:50 PM
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The energy argument is a good point. There are theoretical limits to information storage density, and to the minimum amount of energy for calculations. As far as I know, the theoretical minimum energy for switching one line is kT, where k is the Boltzmann constant and T is the temperature (in K). That's 4e-21 J at room temperature. If we assume that testing an n-bit key takes 1000n switches (an absurdly low estimate), then it takes 5e-16 J per test, and thus 1.75e23 J total to do a brute-force crack of a 128-bit key. The earth's current energy consumption is about 150 PWh per year, or 5.4e17 J per year. That means it would take 300000 years to power the calculation to break the 128-bit key, assuming the same power generation of the earth, assuming absolute theoretical minimal switching energies, and assuming ridiculously small numbers of switches per test. Call me naive, but I don't think the NSA has a secret AES-128 cracking lab...

David Brown
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re: How secure is AES against brute force attacks?
David Brown   5/21/2013 7:14:34 PM
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I made a mistake in my calculations - the theoretical minimum switching energy is kT.ln(2). So it would only take 200000 years to power the calculations!

David Brown
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re: How secure is AES against brute force attacks?
David Brown   5/21/2013 8:39:40 PM
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It is correct that there are ways to reduce the keyspace you need to search - and that future research may reduce this a little more. And it may turn out that in the future, there will be a breakthrough that reduces the search keyspace significantly - but there is no indication of that at the moment. So even with 128-bit AES, the cheapest and most reliable way to break the key is to use one of the two traditional methods - the three B's technique (bribery, burglary, blackmail) or rubber hose cryptoanalysis. And it looks likely to remain that way for a long time yet.

David.L.Fleischer
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re: How secure is AES against brute force attacks?
David.L.Fleischer   5/22/2013 3:35:13 PM
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Pentaflops? Good one.

phpexp1
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Demo
phpexp1   11/13/2013 6:14:43 AM
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There is an online demo for AES encryption and decryption

lister1
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AES weakness
lister1   2/3/2014 1:17:01 PM
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I believe AES weakness is not in the Symmetric algorithm itself.

Rather, IMO, the weakness comes in the randomization of the initialization vector.  We've already heard how NSA underminds the Dual_EC_DRBG.  :)

sansik
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security
sansik   7/14/2014 8:32:55 AM
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The cryptographic algorithms used in Advanced Encryption Standards are more secure due to 128-bit symmetric keys, if someone sets a password containing both letters and symbols it is very hard for any hacker to find out the code. I use a 128 bit key size password on our workflow management systems and I am sure no one will break it, for a better security I use a random password generator that maximizes the security of the password.

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