[Cryptography] Two round secure hashing

[Bill Cox]

On Thu, Apr 24, 2014 at 6:38 PM, Bill Cox <waywardgeek at gmail.com> wrote:

> I'd appreciate feedback on the following dumb idea.  If it works as I
> hope, it will dramatically speed up secure file hashing.  My benchmarks
> from yesterday are out of date, but I was seeing file hashing 5X-ish faster
> than md5sum, and 12X-ish faster than sha256sum.  Here's a simple page I
> wrote on the idea:
>
> http://waywardgeek.net/hashproof.html
>
> I'll read any replies here, but I don't have unmoderated approval for
> posting, so I'll just reply directly to authors.
>
> Bill
>

I'm finding problems in my proof.  In particular, if a message value on the
other track is changed, it is possible to undo the impact it that change
has by changing another message value.  I just realized that this
correction can occur anywhere in the message, even quite far in the hashing
chain, giving the attacker a lot of flexibility in finding collisions.
 I'll have to work on this some more... it may not work out.

Bill
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