[Cryptography] "We need crypto code training" and other obviosities.

[Max Kington]

On 24 Oct 2015 01:35, "John-Mark Gurney" <jmg at funkthat.com> wrote:
>
> ianG wrote this message on Fri, Oct 23, 2015 at 16:18 +0100:
> > If I had to have a stab at what this means, I'd say that crypto
> > programming is 90% good programming, 9% good business understanding and
> > 1% crypto.
> >
> > Just to be flagrant, of course!  What say others?
>

I think it depends entirely on the nature of the crypto system you're
building and the risks the crypto is designed to mitigate. Formal academic
crypto courses (the one on the course I'm doing) is largely about the
mechanisms, the properties of the building blocks and then a little bit
about the practical problems like key management.

For the types of system I build this is might be about right but there's a
lot more to building good distributed systems than writing good code. It
takes experience and practice writing a range of types of systems to design
them well which by and large the cryptography experts don't have.

I see the same thing in my sector. For anyone who has worked in financial
services with quants for any length of time you may have experienced very
capable mathematicians who are convinced they're rock star programmers
because it has to be easier than their core skill.

If you're writing an open ssl like library your ratios probably change to
bias the crypto element more.

> One BIG issue in crypto code is side channel attacks, and no matter
> how good a programmer you are, you aren't going to code for side
> channel attacks because it intentionally makes your program slower...
>

I agree, but significant improvement could be made by being better
developers of systems which focus on *all* of the issues.

> GCM for example will leak like a sieve if you use an 8bit lookup
> table, which is the best/fastest way to implement it on modern
> systems...
>
> This aspect alone puts the crypto at minimum 10-20%.  Yes, it isn't
> complex, but is absolutely manditory.

Again, I think it depends on the nature of the application of the crypto.

>
> --
>   John-Mark Gurney                              Voice: +1 415 225 5579
>
>      "All that I will do, has been done, All that I have, has not."
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