[Edu-sig] Thinking about my class...

kirby urner kirby.urner at gmail.com
Thu Mar 16 16:51:57 CET 2006

Early AM before school in Portland, and my Brother multifunction
printer, soon to be retired (factory remanufactured clone enroute,
after we broke the paper feeder), is printing up a storm.

We'll be doing a simple substitution cipher, i.e. substitute a random
shuffle (permutation) of A-Z and space, for some coherent plaintext
(also in Latin-1), to get garbled ciphertext, then reverse.

Here's my worksheet (decrypt not included):


from random import shuffle
from string import uppercase

def makefunction():
   theletters = list(uppercase[:26] + ' ')
   copyof = theletters[:]
   return dict(zip(theletters, copyof))

def encrypt(plaintext, thekey):
    return ''.join([ thekey[i] for i in plaintext ] )


Use File | New Window to start a new program file.

Save As "something.py" (in site-packages would be OK).

Enter the above code, paying attention to indentation.

Save again.


We import from modules to get additional features.

The file you save is itself a module.

You can import your own modules, as well as modules provided by others.

[ side 2 of this worksheet is something about xml-rpc -- hitting a
Perl utility with a street address, getting back lat/long ]


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