I have heard a lot about the biclique cryptanalysis research on AES, which as far as I know is the closest anyone has got to breaking AES.

Exactly how close did they get? Does this attack propose a credible risk to my using AES today? Exactly how hard would it be to extend their work to fully break AES?

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    $\begingroup$ Are you asking for a list of all known attacks against AES? That would be too broad for a Stack Exchange question. Or are you asking about this specific attack you've read about? If the latter, you need to give some precise reference (such as a link to the article that describes the attack). $\endgroup$ – Gilles 'SO- stop being evil' Apr 21 '12 at 18:35
  • $\begingroup$ Is this the attack you're referring to? If so, a question specifically on that attack would be much more focused, as Gilles says. Underneath your question there is an edit link if you want to revise your question :) $\endgroup$ – user46 Apr 21 '12 at 18:39
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    $\begingroup$ Right - I've gone in with a fairly audacious edit - if you don't like it or it isn't what you meant, do feel free to edit/improve it. I have basically taken out the references to all attacks and asked about this specific one, which should help you get the answers you're looking for, I think. If you need help, do feel free to reply to me here, or via a flag, or ask on meta. $\endgroup$ – user46 Apr 21 '12 at 19:01
  • $\begingroup$ this is the one that i search over the internet.. computescotland.com/… I search about the weakness of AES, and I found this weaknesses, but there is no name that was derived in this attack.. $\endgroup$ – goldroger Apr 22 '12 at 10:27
  • $\begingroup$ But biclique attack is one of the known attack in AES, in biclique attack, is that really a threat in security of AES? $\endgroup$ – goldroger Apr 22 '12 at 10:28

Simply put no.

As per the abstract, those attacks take at most 4 bits off the key space, this still results minimally in 124 bits of security. Put another way, to use these attacks you would need to expend effort roughly proportional to brute forcing an AES key where you already knew four bits of the key and this would take approximately $2^{124}$ operations.

For reference, the standard rule of thumb on security is it must provide about 80 bits currently. Of course, this is to be secure now and not 100 years from now and and something that provides 80 bites of security now could have those eroded later. However 124 is still more than enough of a safety margin.


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