Take the 2-minute tour ×
Cryptography Stack Exchange is a question and answer site for software developers, mathematicians and others interested in cryptography. It's 100% free, no registration required.

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 ?

share|improve this question
add comment

1 Answer 1

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.

share|improve this answer
    
but here they recommended 16 round or more for 128bit blocks : schneier.com/blog/archives/2009/07/another_new_aes.html –  mary Dec 21 '12 at 8:04
1  
@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
2  
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
show 6 more comments

Your Answer

 
discard

By posting your answer, you agree to the privacy policy and terms of service.

Not the answer you're looking for? Browse other questions tagged or ask your own question.