Re: newbie coding programmer...

From: Roger Fleming (roger_for_nntp_at_hotmail.com)
Date: 02/20/04 

Date: Fri, 20 Feb 2004 11:48:51 +1100

mrat wrote:

> It's substitution, but the substitution changes with every letter. So
> it is possible to have the entire message with only one letter. Then
> it adds spaces.

Just to clarify the Rules:
* we get lots of these requests. Many of them are quite annoying. If you
ignore the rules, expect to be ignored.
* you have to given enough information that we could write the program
ourselves. The only thing missing should be the key. (This is known as
Kerkhoff's Second Principle.) You are more likely to get a response if
your description of the algorithm is in a widely understood form, such
as the C language, mathematical notation, or clear pseudocode.
* even then, don't necessarily expect a response. You are asking for
thousands of dollars worth of professional consultancy services for
free. People may analyse your algortihm for you out of curiosity, or
just to be nice, but then again they may not have time to look at it at
all. Even mediocre algorithms may take many hours or days of work to
analyse.
* don't take negative comments personally. We are discussing the
algorithm, not you.
* providing the ciphertext is largely irrelevant. An algorithm can be
worthlessly weak without necessarily being able to break any particular
ciphertext. For example, you provided 42 non-whitespace characters. Even
a simple substitution cipher - just about the weakest cipher known -
typically requires 60 or so characters to break. (But a significant
number of messages can be broken with much less!)

Cheers,
Roger

 

Relevant Pages

  • Re: Are natural languages secure ciphers?
    ... the algorithm isn't strong enough. ... >> produces ciphertext which is indistinguishable from random noise ... unknown to the linguistic community, it won't remain unknown that long. ... Paul Schlyter, Grev Turegatan 40, SE-114 38 Stockholm, SWEDEN ...
    (sci.crypt)
  • Re: Announcing the "Chaocipher Clearing House"
    ... Assume that if we knew the algorithm, ... makes the ciphertext indistinguishable from random data through ... cryptanalysis will fail. ... secure as modern number theoretic cryptosystems, ...
    (sci.crypt)
  • Re: OK What do you need? was:Re: Please test this encryption
    ... > strong encryption can be broken with brute force methods. ... than key material and some idea of what the plaintext will look like) can be ... a short/single sample is sufficient to figure out an algorithm. ... show logically that a single ciphertext string is insufficient to determine ...
    (sci.crypt)
  • Re: Please test this encryption
    ... the algorithm must remain secure even if the enemy ... What about the longer ciphertext? ... on my cracker program but your encryption program would be worthless. ...
    (sci.crypt)
  • Re: Meganet on Cryptogram again
    ... > If Meganet's algorithm is insecure, then someone needs to prove that by ... You should write a book called "The optimist's guide to security." ... the people with considerable security expertise who help the community ... disassemble their code and carefully analyse it. ...
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