[Cryptography] Nu supr unbrakable cripto

[Bill Cox]

On Fri, Jan 1, 2016 at 12:09 PM, Christian Huitema <huitema at huitema.net>
wrote:

> On Thursday, December 31, 2015 8:01 AM, Bill Cox wrote:
> >...
> > The basic strategy is to create a crypto grade hash function, and
> > then turn that into a crypto-grade symmetric-key encryption
> > algorithm.
>
> If the hash function uses the Merkle–Damgård construction, isn't that
> going full circle? Create a hash function from a symmetric encryption
> algorithm, and then create a symmetric encryption algorithm from the hash
> function?
>
> -- Christian Huitema
>

Works for me :)  If a proper MAC were added, it could be faster and simpler
to just use the hash function in counter mode to generate data for a stream
cipher, with the only real downside being a stronger dependence on the
unpredictable nature of the nonce.  Two files with the same nonce and key
XORed together are just the plain texts of the files XORed together.  The
extra work in the block cipher has some use.

Bill
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