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From: WTShaw on 21 Mar 2010 02:02
More options Mar 19, 2:05 am


Classification of ciphers is a problem. Trying to force every cipher
into one
of two categories can be misleading. As it goes ciphers can be
complex
with a combination of primitives involved. I favor the category of
Hybrid as a catch-all, with possible new classifications that might
better describe one or certain related ciphers that might be grouped.

Classification jargon for one I have worked with for years has been a
question.
A broad name should be descriptive of process. Something that fits for
it is
the classification of a Spiral Cipher, a narrow definition.

I see other possible classifications for ciphers that are outside of
the
major two groups, but Hybrid is good enough for many that have no
central
thrust of uniqueness.

Block, stream, and spiral are sufficiently pure in meaning to be
recognizable in many cases. Can you suggest others that actually do
the same, really tell the story? Care should be made not to exclude
from classification ciphers that are not identical to a narrow
definition
like stream ciphers that might include be beyond a very narrow
definition
often used.

New, different, interesting, productive, and related efforts should
be
encouraged and not otherwise. Also, meaningful general descriptions
as well as details when requested or available would be good.

Many of the greatest scientific discoveries were done by few people
working alone or in limited groups.


On Mar 16, 5:06 pm, "J.D." <degolyer...(a)yahoo.com> wrote:
> @Maaartin
> > I've never seen a pair of definitions for stream and block ciphers,
> > which are clear, non-overlapping and include all symmetric ciphers.
> > For example, a block cipher in CBC mode is obviously a symmetric
> > cipher, but neither stream nor block cipher according to most
> > definitions I've seen.
> I don't see why the definitions for block and stream ciphers should
> necessarily have to include all symmetric ciphers. It's not like we
> are talking about block-ciphers and "non-block-ciphers". In that
> vein, I do not consider block cipher _modes_ to themselves be block
> ciphers (except arguably ECB mode) -- they are symmetric cipher
> algorithms that use a block cipher as a component. But my use of the
> terminology may be idiosyncratic in this regard...

From: Mok-Kong Shen on 21 Mar 2010 06:26
WTShaw wrote:

> Classification of ciphers is a problem. Trying to force every cipher
> into one
> of two categories can be misleading. As it goes ciphers can be
> complex
> with a combination of primitives involved. I favor the category of
> Hybrid as a catch-all, with possible new classifications that might
> better describe one or certain related ciphers that might be grouped.

Personally I don't think classification is a very important issue.
If a cipher serves well its intended purpose, it doesn't matter
even if some people refuse to name it as a cipher at all, or does it?

M. K. Shen
---------------------------------------------------------------------

OT: BTW, IMHO one has similar classification difficulties in separating
democratic from non-democratic countries or regimes that respect
human rights from those that don't but cry when others violate them.
From: WTShaw on 23 Mar 2010 00:59
On Mar 21, 5:26 am, Mok-Kong Shen <mok-kong.s...(a)t-online.de> wrote:
> WTShaw wrote:
> > Classification of ciphers is a problem.  Trying to force every cipher
> > into one
> > of two categories can be misleading. As it goes ciphers can be
> > complex
> > with a combination of primitives involved.  I favor the category of
> > Hybrid as a catch-all, with possible new classifications that might
> > better describe one or certain related ciphers that might be grouped.
>
> Personally I don't think classification is a very important issue.
> If a cipher serves well its intended purpose, it doesn't matter
> even if some people refuse to name it as a cipher at all, or does it?
>
> M. K. Shen
> ---------------------------------------------------------------------
>
> OT: BTW, IMHO one has similar classification difficulties in separating
> democratic from non-democratic countries or regimes that respect
> human rights from those that don't but cry when others violate them.

Personally, the problems is that few people know the colorful range of
cyphers when they dwell on some aspect of other. Usefulness is surely
one way to look at them. History of ciphers can be entertaining and
reveal the expertise of the users, and especially what we learned
because of them.

Some want to find the one that will do everything desired, but that
never can exist because desires differ greatly, a whole spectrum of
them. In studying lesser ciphers, lots can be learned, even pointing
to really strong ones that are worth noting.

I mentioned a few ciphers based on some overall difference that makes
a few somewhat grouped together. Along with that list would be
coordinate ciphers of which the toy BLT would be a member in a three-
dimensional sense. Something like a Grille cipher is just a form of
transposition but nevertheless an oddity.

Fractionated Morse is a stream cipher in that individual characters
don't necessarily register as having the same size. While my
variation of it, Sam's Club 26of27, uses a more complex key generation
scheme and it handles all the usual keyboard characters and simple
formatting. Scaling to 80of81 makes another fairly simple cipher. I
suppose one of the things that I do like is programming ciphers and
give them to friends for their own amusement.

If modern ciphers represents a school of believers. that would be a
classification. Historic can't mean prior to 1900 as so much use and
understanding of related matters came after that time as well.
From: WTShaw on 25 Mar 2010 02:11
On Mar 22, 11:59 pm, WTShaw <lure...(a)gmail.com> wrote:

>
> If modern ciphers represents a school of believers. that would be a
> classification.  Historic can't mean prior to 1900 as so much use and
> understanding of related matters came after that time as well.

Beliefs may be well founded or they may not. Note the so-called
fallen ciphers after big names were their principal reason to be
accepted. Like religion and politics, crypto needs doubters to keep
everything honest.
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