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From: Mok-Kong Shen on 29 Jul 2010 07:27

I have the vague impression that chaos theory doesn't
belong to the tools used/favoured by the majority of
researchers in in the field of crypto. From time to time,
I encounter however published articles on applications of
chaos theory to crypto in reknown scientific journals, a
recent one being:

W. Kinzel et al., On chaos synchronization and secure
communication. Phil. Trans. R. Soc. A(2010) 368, 379-389.

Could some knowledgeable person say something on the
importance (fruitfulness of rendering useful results) or
not of chaos theory to crypto?

Thanks.

M. K. Shen
From: unruh on 29 Jul 2010 10:05
On 2010-07-29, Mok-Kong Shen <mok-kong.shen(a)t-online.de> wrote:
>
> I have the vague impression that chaos theory doesn't
> belong to the tools used/favoured by the majority of
> researchers in in the field of crypto. From time to time,
> I encounter however published articles on applications of
> chaos theory to crypto in reknown scientific journals, a
> recent one being:
>
> W. Kinzel et al., On chaos synchronization and secure
> communication. Phil. Trans. R. Soc. A(2010) 368, 379-389.
>
> Could some knowledgeable person say something on the
> importance (fruitfulness of rendering useful results) or
> not of chaos theory to crypto?

While a crypto system is a chaotic system in some sense, most chaotic
systems have attractor cycles, etc. There are organized structures
within the chaos. Organized structures are anathema to crypto. Thus,most
chaotic systems are useless for crypto.

>
> Thanks.
>
> M. K. Shen
From: Mok-Kong Shen on 29 Jul 2010 10:18
unruh wrote:

> While a crypto system is a chaotic system in some sense, most chaotic
> systems have attractor cycles, etc. There are organized structures
> within the chaos. Organized structures are anathema to crypto. Thus,most
> chaotic systems are useless for crypto.

Though lacking knowledge in chaos theory, I tend also to think so. But
the appearence of articles in well-known journals seems to contradict
that.

M. K. Shen

From: Scott Contini on 29 Jul 2010 19:08
On Jul 29, 9:27 pm, Mok-Kong Shen <mok-kong.s...(a)t-online.de> wrote:
> I have the vague impression that chaos theory doesn't
> belong to the tools used/favoured by the majority of
> researchers in in the field of crypto. From time to time,
> I encounter however published articles on applications of
> chaos theory to crypto in reknown scientific journals, a
> recent one being:
>
>    W. Kinzel et al., On chaos synchronization and secure
>    communication. Phil. Trans. R. Soc. A(2010) 368, 379-389.
>
> Could some knowledgeable person say something on the
> importance (fruitfulness of rendering useful results) or
> not of chaos theory to crypto?
>
> Thanks.
>
> M. K. Shen

Handwaving, philosophical suggestions that chaos
theory could give good crypto are of zero value.
If one has a good solution that uses chaos theory
and solves important problems in crypto, then they
should propose it and let the crypto people analyse
it. If the crypto community likes it, then and only
then will chaos theory be considered a useful tool
for cryptography. That's not to say that it can't be
useful. I'm just saying that I haven't seen any good
solutions yet.

From my own experience, chaos theory has gotten a
bad reputation in crypto because of frequent
proposed applications by people who do not understand
the requirements we have in crypto. I don't really
know anything about chaos theory, but I haven't needed
to know anything to cryptanalyse some designs that I
have seen. It is not enough for a prng based on
chaos theory to look random -- it also has to be
unpredictable. It is not enough for a hash function
based on chaos theory to appear to give random looking
outputs. It has to be hard for intelligent adversaries
to create collisions. Intelligent adversaries, not
dumb ones!

This is not to disparage chaos theory as a science
in any way. It is simply pointing out the fact that
attempts at using chaos theory in crypto have not
been successful. That's all I have to say about
this subject so don't expect me to reply to it again.

Scott

From: MrD on 30 Jul 2010 03:32
unruh wrote:
>
> While a crypto system is a chaotic system in some sense, most chaotic
> systems have attractor cycles, etc. There are organized structures
> within the chaos. Organized structures are anathema to crypto.
> Thus,most chaotic systems are useless for crypto.

The HWRNGs built-in to some CPUs are based on two or more free-running
oscillators, commonly (so I understand) using a ring of gates to make an
oscillator. It strikes me that as a source of randomness such a circuit
is as much turbulent as random, and I understand that turbulence is more
a chaotic phenomenon than a truly random one.

I'm pretty much out of my depth on this. I'd appreciate the views of
someone who knows something about the subject. I'm suspicious of this
type of TRNG on the grounds that Unruh has given; and because I believe
that the oscillators are exhibiting turbulence and not randomness.

Are my suspicions reasonable?

--
MrD.
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