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Author Topic: AES-256 less secure than AES-128  (Read 5269 times)

gjehle

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AES-256 less secure than AES-128
« on: August 01, 2009, 07:48:19 AM »


This just in from #mircryption
I'll just quote it here since lizzy didn't want to sign up just for that:

Quote
123446 <lizzy_> hi guys
123504 <lizzy_> we have a BIG problem, at the Pre-panic stage:
123523 <lizzy_> look at today's slashdot.org
123550 <lizzy_> Cryptography is all about safety margins. If you can break n round of a cipher, you design it with 2n or 3n rounds. What we're learning is that the safety margin of AES is much less than previously believed. And while there is no reason to scrap AES in favor of another algorithm, NST should increase the number of rounds of all three AES variants -- now, before there is a reason to panic.
123614 <lizzy_> At this point, I suggest AES-128 at 16 rounds, AES-192 at 20 rounds, and AES-256 at 28 rounds. Of maybe even more; we don't want to be revising the standard again and again.
123614 <lizzy_> And, even more strongly, I suggest that people don't use AES-256. AES-128 provides more than enough security margin for the forseeable future.
123614 <lizzy_> Schneier on Security: Another New AES Attack (1 August 2009)
123614 <lizzy_> http://www.schneier....another_new_aes.html
123614 <lizzy_> http://snipurl.com/ogstr
124102 <lizzy_> ..
124143 <lizzy_> i also propose that the number of rounds used be shown ,eg: AES256-16
125559 <lizzy_> see also: slashdot.org

mouser

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Re: AES-256 less secure than AES-128
« Reply #1 on: August 01, 2009, 07:59:03 AM »
fascinating stuff.

Crush

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Re: AES-256 less secure than AES-128
« Reply #2 on: August 01, 2009, 08:31:19 AM »
 ;D  Use the Crush Cryptonizer and you can decide how many rounds and key-lengths shall be used for encryption. If you wish to make 5.000.000 rounds on a key with the length of 1 MB or several GB ... no problem!
« Last Edit: August 01, 2009, 08:33:22 AM by Crush »

housetier

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Re: AES-256 less secure than AES-128
« Reply #3 on: August 01, 2009, 09:55:22 PM »
I heard this as well from a friend who knows the crypty stuff. He also assured me to use aes-128 over aes-256.