[Cryptography] List of Proven Secure Ciphers / Hashes

[Bill Frantz]

On 9/15/14 at 8:41 AM, jkatz at cs.umd.edu (Jonathan Katz) wrote:

>There is no cryptosystem whose security (in any standard sense) 
>can be reduced to an NP-hard problem. The issue, intuitively, 
>is that NP-hardness is a *worst-case* notion, whereas we want 
>cryptosystems to be hard *on the average*.

The requirements of crypto turn what is wanted around like a lot 
of things in security. Most often people ask, "What can that 
computer system do?" The security guys ask, "What can I be sure 
it can't do?"

With computational difficulty, we aren't asking, "What is the 
hardest case?", instead we are asking, "What is the easiest 
case?". Sometimes, like with DES weak keys, we find a limited 
number of cases where the answer is, "Too easy." and we avoid 
those cases. If there are too many of these easy cases, we worry 
about the security of the crypto.

Cheers - Bill

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