[Cryptography] AES [was NSA and cryptanalysis]

William Muriithi william.muriithi at gmail.com
Tue Sep 17 11:01:43 EDT 2013

> >> Such a backdoor would be feasible.
> > It might be feasible in theory (and see the Illinois Malicious
> > Processor as an example) but I think it would be hard to pull off
> > well -- too hard to account for changes in future code, too hard to
> > avoid detection of what you've done.
> Not sure this is true. If instead of leaking via the RNG, you leak via
> the cryptographic libraries *and* the windows socket libraries, then
> while there are probably two different teams involved, there is only one
> manufacturer - Microsoft.
> Ok that would exclude non-windows systems, which in this world of BYOD
> means an increasing number of ios or android devices - but the odds of
> one end or the other of any given exchange being a MS platform are
> good.  Provided the cryptographic libraries are queried in a specific
> manner for tcp sequence numbers (which can be enforced) the winsock team
> never need know how those are generated, leaving just the cryptographic
> library holding both the input and output.
I think you are over estimating how entrenched Windows is. First, its not
widely used on server side. Most of the server side is Linux based so if
you are on android or IOS, there is high chance you are not using Windows
on both ends.

Then they also are not as dominant as they were in the 90s and early 2000s.
Apparently, if you consider mobile devices, they make 30% of the computers
out there. So, for this to work, it got to be done across vendors.
> >
> > On the other hand, we know from the press reports that several
> > hardware crypto accelerators have been either backdoored or
> > exploited. In those, leaking key material to observers in things like
> > IVs or choices of nonces might be quite feasible. Such devices are
> > built to be tamper resistant so no one will even notice if you add
> > features to try to conceal the "extra functionality" of the device.
> >
> > For the Intel chips, I suspect that if they've been gimmicked, it
> > will be more subtle, like a skew in the RNG that could be explained
> > away as a manufacturing or design error. That said, things like the
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