Any product of nanotech which contain active elements, i.e. is
not a completely passive structure, depending on its fixed
material properties for its usefulness; will need to have
intercommunication between its elements. The exact medium that
this communication uses could vary, as it might be chemical,
electrical, mechanical, or maybe some application of quantum
mechanics,

but it will be strongly desirable for it to be secure.

If nanotech intercommunication is not secure then this introduces
the possibility of it being 'hacked', either to change the
behaviour of the nanotech, or to extract some information that
the system desires to keep secure. This hacking would almost
certainly be itself done by nanotech.

Unfortunately adding security to nanotech intercommunication is
going to have overheads, and the usual problems of managing keys.
However, if the security mechanism is built into the nanotech,
for example into a set of nanotech manipulators intended to be
used for just one purpose, then a lot of the normal problems
about key distribution might go away.

I was speculating whether the security mechanism could be
something like the Enigma Machine (see Wikipedia; you could
easily have more than three rotors),

In general I would agree with you, but there are
likely to be
communication techniques which are not feasible
using the macro
scale properties of materials, and rely on QM
techniques which
can only be effectively utilised by nano scale
structured
materials, possibly dynamically manipulated using
nanotech. I
wouldn't rule these out.
SNIP

--- Rory McLean <rory@romsys.demon.co.uk> wrote:
SNIP
In general I would agree with you, but there are
likely to be communication techniques which are
not feasible using the macro scale properties of
materials, and rely on QM techniques which
can only be effectively utilised by nano scale
structured materials, possibly dynamically
manipulated using nanotech. I wouldn't rule
these out.
SNIP

Transmitting encypted information requires only a
laser and a fibre optic cable. We don't know if a
laser will yet be a MNTed product but these can be
produced easily with existing manufacturing
techniques. Surely in a post-MNT world these two 20th
Century inventions will be cheap enough to be
ubiquitous if desired.

WWII ENIGMA communication technologies were hacked by
cryptographers without the assistance of modern
computers (in response to your suggestion MNT should
use an ENIGMA-based encryption strategy).

Rory McLean <rory@romsys.demon.co.uk> writes:
Rory McLean <rory@romsys.demon.co.uk> writes:
[snip]

I was speculating whether the security mechanism could be
something like the Enigma Machine (see Wikipedia; you could
easily have more than three rotors),

If you're desire is to have your encryption system broken immediately,
choosing the state of the art from 1935 is perhaps a reasonable
choice. If what you're trying to do is actually protect communications
links, the issue is well understood already. Cryptography is a big
area of study, and there are lots of good modern books that can
provide you with an introduction to the field, not to mention a lot of
research and discovery that has happened in the last 60 years or so.

With some simple modifications it is possible to take something
very similar to the rotor system of the Enigma Machine and
create an apparently continuous stream of white noise with
apparently random fluctuations.

I'd suggest not discussing a topic you don't understand. I named
several books you could read to correct your lack of understanding in
my previous posting. If you have trouble paying for them you can take
them out at a local library. Ignorance is easily corrected with
education.

When I taught a university class in the topic, I used to use
Schneier's "Applied Cryptography" and "Handbook of Applied
Cryptography" by Menezes, Oorschot, and Vanstone as the primary
texts. Those books are now somewhat obsolete -- they don't cover
topics like AES and they were all written long before MD5 got broken
and such. None the less, you could start learning there.

I would agree with you that Schneier has some interesting things
to say,

Then perhaps you should read his books at least once. I'll be blunt --
your posting made it very clear that you haven't ever cracked either
of his texts on this topic, or any other for that matter.

Perry

[And your humble moderator will bluntly suggest we maintain a civil tone
in the future, thank you. --JSN]

Some work will be possible on this basis, and these links can be
made quite secure. But, trying to do all the nanotech work
requiring communication using a tethered system, particularly if
the system of nanotech is needing to radically change its shape
and/or size may be quite difficult, and a complication that you
would wish to avoid.

WWII ENIGMA communication technologies were hacked by
cryptographers without the assistance of modern
computers (in response to your suggestion MNT should
use an ENIGMA-based encryption strategy).

The decryption methods used at Bletchley Park were quite
ingenious, and the later availability of the Bombe to do some of
the brute-force work made amazing use of the available
technology. However, the user mistakes and technical
shortcomings of Enigma that enabled this decryption are now
quite well understood, and it is reasonably easy to work around
them.

A rotor-based system (or its electronic equivalent) has the
great virtues of simplicity and speed,

Rory McLean <rory@romsys.demon.co.uk> writes:
[snip]

WWII ENIGMA communication technologies were hacked by
cryptographers without the assistance of modern
computers (in response to your suggestion MNT should
use an ENIGMA-based encryption strategy).

The decryption methods used at Bletchley Park were quite
ingenious, and the later availability of the Bombe to do some of
the brute-force work made amazing use of the available
technology. However, the user mistakes and technical
shortcomings of Enigma that enabled this decryption are now
quite well understood, and it is reasonably easy to work around
them.

A rotor-based system (or its electronic equivalent) has the
great virtues of simplicity and speed,

No, actually. There would be no advantages whatsoever to such a
system. A rotor based system would be slow, would not be any simpler
than modern methods, and would have other substantial disadvantages
over modern Feistel ciphers, some of which, like AES, are
extraordinarily fast, well understood, and have been subjected to
rigorous analysis.
[snip]

A rotor-based system (or its electronic equivalent) has the
great virtues of simplicity and speed,

No, actually. There would be no advantages whatsoever to such a
system. A rotor based system would be slow, would not be any simpler
than modern methods, and would have other substantial disadvantages
over modern Feistel ciphers, some of which, like AES, are
extraordinarily fast, well understood, and have been subjected to
rigorous analysis.
[snip]

I would be interested in hearing what sort of alternative
synchronous stream cipher you think would provide properties
desirable for nanotech communications.

If you believe it would be an issue, I assume one which does not
use an algorithm which would be susceptible to attack by quantum
computing would be preferable.

I was a bit reluctant to say too much because of wishing to stay
'on topic', but there is an introduction to encryption, below.