Re: Fun/Funny Fractal Encryption...

From	Richard Heathfield <rjh@cpax.org.uk>
Newsgroups	comp.lang.c, sci.crypt
Subject	Re: Fun/Funny Fractal Encryption...
Followup-To	sci.crypt
Date	2015-07-15 15:52 +0100
Organization	go, ion artisan!
Message-ID	<mo5s0m$um6$1@dont-email.me> (permalink)
References	<mnhpm5$fh9$1@speranza.aioe.org> <mnp683$pld$1@speranza.aioe.org>

Cross-posted to 2 groups.

Followups directed to: sci.crypt

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[Followups set to sci.crypt]

On 10/07/15 20:25, Chris M. Thomasson wrote:

<snip>

> I am VERY interested in any cyrpto analysis that can crack the
> formula/key responsible for encrypting several messages with
> the same public key/derived-fractal. Keep in mind that the derived
> fractal, or public key should be mathematically tied to the original
> private fractal.

Chris, the first step is to try to crack the algorithm yourself.

That doesn't necessarily mean recovering a plaintext from a ciphertext 
(without the key). Here are some ways to illustrate that a cipher is 
insecure (not all will necessarily apply to every cipher, but most will 
apply to most):

1) A frequency analysis shows that the distribution of ciphertext 
characters varies significantly from what you would expect from 
randomly-generated data. This is a relatively easy task. 
(Transposition-only ciphers are bound to fail this test, which doesn't 
necessarily mean they're no use.)

2) A change of a single bit in the plaintext results in a trifling 
change in the ciphertext. One would expect, in a strong cipher, that the 
alteration of a single bit in the plaintext would result in roughly half 
the bits of the ciphertext changing (and these changes would be 
distributed apparently at random through the file).

3) The cipher falls to the usual attacks on monoalphabetic or 
polyalphabetic substitution ciphers. (Look up "Kasiski" and/or "Index of 
Coincidence".)

4) Given a known plaintext (i.e. you have the ciphertext and you know at 
least some of the plaintext that generated it), you can recover the key.

Those might be considered the most basic attacks. You need to try these 
for yourself. You will never design a first-class (or even second- or 
third-class) cipher if you don't acquire some experience in breaking 
ciphers. (And it's quite a diverting exercise in its own right.)

When you ask "can anyone break this?", they're much more likely to *try* 
if you can say "the ciphertext is indistinguishable from random, the 
avalanching is up to snuff, and I tried the foo, bar, and baz attacks, 
but couldn't make any headway" - in other words, if you've eliminated 
the obvious and also shown that you've made an effort.

-- 
Richard Heathfield
Email: rjh at cpax dot org dot uk
"Usenet is a strange place" - dmr 29 July 1999
Sig line 4 vacant - apply within

Thread

Fun/Funny Fractal Encryption... "Chris M. Thomasson" <nospam@nospam.nospam> - 2015-07-07 17:08 -0700
  Re: Fun/Funny Fractal Encryption... Richard Heathfield <rjh@cpax.org.uk> - 2015-07-08 01:12 +0100
    Re: Fun/Funny Fractal Encryption... "Chris M. Thomasson" <nospam@nospam.nospam> - 2015-07-07 17:19 -0700
      Re: Fun/Funny Fractal Encryption... Robert Wessel <robertwessel2@yahoo.com> - 2015-07-07 22:29 -0500
        Re: Fun/Funny Fractal Encryption... "Chris M. Thomasson" <nospam@nospam.nospam> - 2015-07-07 22:43 -0700
          Re: Fun/Funny Fractal Encryption... Robert Wessel <robertwessel2@yahoo.com> - 2015-07-08 03:23 -0500
          Re: Fun/Funny Fractal Encryption... James Kuyper <jameskuyper@verizon.net> - 2015-07-08 07:36 -0400
            Re: Fun/Funny Fractal Encryption... Richard Heathfield <rjh@cpax.org.uk> - 2015-07-08 12:52 +0100
            Re: Fun/Funny Fractal Encryption... "Chris M. Thomasson" <nospam@nospam.nospam> - 2015-07-08 11:10 -0700
              Re: Fun/Funny Fractal Encryption... James Kuyper <jameskuyper@verizon.net> - 2015-07-08 14:46 -0400
                Re: Fun/Funny Fractal Encryption... "Chris M. Thomasson" <nospam@nospam.nospam> - 2015-07-08 12:10 -0700
                Re: Fun/Funny Fractal Encryption... Richard Heathfield <rjh@cpax.org.uk> - 2015-07-08 20:41 +0100
                Re: Fun/Funny Fractal Encryption... "Chris M. Thomasson" <nospam@nospam.nospam> - 2015-07-09 09:55 -0700
                Re: Fun/Funny Fractal Encryption... "Chris M. Thomasson" <nospam@nospam.nospam> - 2015-07-09 11:18 -0700
                Re: Fun/Funny Fractal Encryption... Richard Heathfield <rjh@cpax.org.uk> - 2015-07-09 19:25 +0100
                Re: Fun/Funny Fractal Encryption... "Chris M. Thomasson" <nospam@nospam.nospam> - 2015-07-09 13:49 -0700
                Re: Fun/Funny Fractal Encryption... Richard Heathfield <rjh@cpax.org.uk> - 2015-07-09 22:09 +0100
      Re: Fun/Funny Fractal Encryption... Malcolm McLean <malcolm.mclean5@btinternet.com> - 2015-07-08 00:49 -0700
  Re: Fun/Funny Fractal Encryption... "Chris M. Thomasson" <nospam@nospam.nospam> - 2015-07-07 23:05 -0700
    Re: Fun/Funny Fractal Encryption... "Chris M. Thomasson" <nospam@nospam.nospam> - 2015-07-07 23:15 -0700
  Re: Fun/Funny Fractal Encryption... "Chris M. Thomasson" <nospam@nospam.nospam> - 2015-07-10 12:25 -0700
    Re: Fun/Funny Fractal Encryption... "Chris M. Thomasson" <nospam@nospam.nospam> - 2015-07-10 15:09 -0700
    Re: Fun/Funny Fractal Encryption... Richard Heathfield <rjh@cpax.org.uk> - 2015-07-15 15:52 +0100
    Re: Fun/Funny Fractal Encryption... "Chris M. Thomasson" <nospam@nospam.nospam> - 2015-07-31 13:40 -0700
      Re: Fun/Funny Fractal Encryption... "Chris M. Thomasson" <nospam@nospam.nospam> - 2015-07-31 13:43 -0700
        Re: Fun/Funny Fractal Encryption... "Chris M. Thomasson" <nospam@nospam.nospam> - 2015-07-31 13:46 -0700
      Re: Fun/Funny Fractal Encryption... "Chris M. Thomasson" <nospam@nospam.nospam> - 2015-08-21 14:45 -0700
        Re: Fun/Funny Fractal Encryption... Ben Bacarisse <ben.usenet@bsb.me.uk> - 2015-08-22 01:29 +0100
          Re: Fun/Funny Fractal Encryption... "Chris M. Thomasson" <nospam@nospam.nospam> - 2015-08-21 20:03 -0700
            Re: Fun/Funny Fractal Encryption... Ben Bacarisse <ben.usenet@bsb.me.uk> - 2015-08-22 13:02 +0100
              Re: Fun/Funny Fractal Encryption... "Chris M. Thomasson" <nospam@nospam.nospam> - 2015-08-22 18:15 -0700
    Re: Fun/Funny Fractal Encryption... "Chris M. Thomasson" <nospam@nospam.nospam> - 2015-08-16 12:10 -0700
      Re: Fun/Funny Fractal Encryption... luser droog <luser.droog@gmail.com> - 2015-08-22 22:49 -0700

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