[Cryptography] How to find hidden/undocumented instructions

[Rui Paulo]

On Sun, 2017-08-06 at 12:09 -0400, grarpamp wrote:
> On Sat, Aug 5, 2017 at 6:15 PM, Rui Paulo <rpaulo at me.com> wrote:
> > On Aug 2, 2017, at 22:49, grarpamp <grarpamp at gmail.com> wrote:
> > > 
> > > This is nice work. These sort of fuzzers and searchers need a
> > > distributed network version to cover more space deeper and
> > > faster.
> > 
> > I attended his talk at DEF CON.  I’m not sure if it’s in the
> > slides, but he can do a full run in a day or less by using multiple
> > cores and with some nice optimizations, so I don’t think we need
> > any distributed network.
> 
> Define "full run". Brief read of paper seems the software is not
> designed to exhaust all possible instructions... ie: from 0x0 to
> 0xf....

I think you need to keep reading the rest of the presentation as well:

https://media.defcon.org/DEF%20CON%2025/DEF%20CON%2025%20presentations/
DEFCON-25-Christopher-Domas-Breaking-The-x86-ISA.pdf

Page 20 and onwards.

The paper has a lot more details including the "page split" technique. 
I recommend you finish reading the paper.

-- 
Rui Paulo