[Cryptography] An Open Source Analysis of NSA Cryptologic Capabilities

[Dave Howe]

On 17/09/2015 16:30, Salz, Rich wrote:
>
>
> > The occasional cryptanalytic success implies that the NSA is
> generally more advanced, but not always.
>
> I am probably being dumb, but I don't see how the timeline justifies
> that conclusion.
>
> The only datapoint that we seem to be confident about is that the NSA
> quietly strengthened DES against differential attacks before the
> public community knew of them.

  Not convinced all of that statement is true. It is now reasonably well
established both that IBM knew about differential attacks and were asked
to keep quiet about them, *and* that the NSA knew that when they
strengthened DES against them. It would seem reasonable therefore that
the NSA quietly strengthened DES against the attack because they knew it
was no longer their own secret, and didn't trust it not to leak from
IBM.  They could well have also known about linear, and not strengthened
DES against that because they believed that knowledge was still
restricted to themselves, hence strengthening against it would be a
disclosure.
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