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we don't want change standard just after every attack, now for AES 128bit blocks i think 16 round is secure, but what is best round amount ? we had attack for 7 round then 10 round and it going so on i think so is better we use a better standard. how many round you think we use is better for a long time ?

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up vote 4 down vote accepted

The AES standard specifies the use of 10 rounds with 128-bit keys. Anything other than this is, by definition, not AES. There are no known effective attacks against standard AES-128.

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but here they recommended 16 round or more for 128bit blocks : – mary Dec 21 '12 at 8:04
@mary Schneier said, more or less, if he would be the one to standardize a new encryption algorithm based on the current AES algorithm, he would chose more conservative round counts. But even if this were done, the resulting algorithm certainly would get a new name, not AES-128, to avoid confusion. – Paŭlo Ebermann Dec 21 '12 at 8:28
@Paŭlo Ebermann♦ so we use 16 round for 128blocks or not ? (if not i'm really worry about new attacks in the future because as Schneier said attacks just getting better not worst ) – mary Dec 21 '12 at 8:59
@mary For now, use the standard AES-128 (with 10 rounds). When someone standardizes a variant with 16 rounds (and there are implementations available in common crypto libraries), you can think about switching to that. – Paŭlo Ebermann Dec 21 '12 at 9:05
There is an easy way to get 14 rounds with 128 bit blocks: It's called AES-256. Expanding a 128 bit key into a 256 bit key, if you want to do so, is easy. – CodesInChaos Dec 21 '12 at 9:39

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