#7123: cryptanalysis of the shift cipher
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Reporter: mvngu | Owner: somebody
Type: enhancement | Status: needs_work
Priority: major | Milestone: sage-4.1.3
Component: cryptography | Keywords:
Work_issues: | Author: Minh Van Nguyen
Reviewer: | Merged:
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Changes (by rbeezer):
* status: needs_review => needs_work
Comment:
Hi Minh,
This is looking real good. Just some details and questions:
1. In the first paragraph of the doc string for
{{{characteristic_frequency()}}} you talk about plaintext and ciphertext.
Not sure somebody looking at this monoid code will be doing crypto. Could
you make the description more confined to properties of the monoid - just
describe it as a property of letters in English usage? The distinction
with the {{{frequency_distribution()}}} is very good, so retain that.
2. Does {{{frequency_distribution()}}} need documentation on its inputs?
And should you change the nature of the output? Perhaps you should stick
to returning a probability space, and then just call {{{function()}}} on
it as needed to get the dictionary you want. Maybe somebody else will
want to get something different from the probability distribution and want
the more general object? In any event, the first line of the docstring
doesn't match the behavior.
3. Looked like there were some stray commented-out code statements in the
cryptanalysis code? Maybe you could review those and take out any that
might be misleading.
4. You probably don't need to give me credit for the chi-square and
squared-differences stuff, they are pretty standard measures of
differences. I also found the [SavHar99] reference more misleading than
helpful.
5. On to affine cipher......
Rob
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Ticket URL: <http://trac.sagemath.org/sage_trac/ticket/7123#comment:17>
Sage <http://www.sagemath.org>
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