MCS 150

Cryptanalysis

January Term 2001

Applets

CipherClerk (encipher/decipher with Vigenere, columnar transposition and others)
Another Vigenere applet
Hill cipher and RSA (note this applet associates 0..25 with A..Z, so enter numbers not letters)
Help with cryptograms
Practice using the Euclidean algorithm (Paul Garrett, U. Minnesota)
GCD as a linear combination (running Euclidean algorithm backwards) (David Sumner, SC)

Maple

It is extremely helpful to have the aid of a general purpose symbolic-manipulation and computational mathematics program. One of the best and most widely available is MAPLE. As you go into technical fields, or even nontechnical fields that are growing increasingly reliant on technology, you may find it very useful to be able to carry out simple computations with the aid of a computer math system.

There is a lot of online documentation for MAPLE. Some useful resources are listed below.

MAPLE's help system makes it very easy to plunge right into MAPLE computations. Double-click on the ``Help'' button on the
menu bar to bring up the help browser. By working your way through the help topics, you may find the commands you need to study. At the end of each Help topic is a set of examples of the use of the command. You may cut-and-paste these commands into your MAPLE session. Then by tailoring the command to your needs, you may complete the calculation you desire. This method-of-operation avoids many syntax errors.

Maple Worksheets

To download these programs push shift-click in Netscape over the link to bring up the dialog box for downloading.

Basics (needed for DW worksheets) crypt.mpl
Vigenere

vigenere.mpl (DW)

This file contains the Maple programs for decoding and encoding the Vigenere cipher. You don't use this directly; it is loaded by the other worksheets.

vigenere.mws (DW)

This is a Maple worksheet that loads vigenere.mpl and demonstrates Vigenere ciphers.

vigen_decode.mws (DW)

Maple worksheet for Vigenere codes. Has complete programs in buttoned up sections. Click the buttons to see the sections, and press enter on each command to activate it.

Hill Cipher

hillcipher.mpl (JH,MM) (1/16/01)

This file contains the Maple programs for decoding and encoding the Hill cipher. You don't use this directly; it is loaded by the other worksheets.

hillcipher.mws (JH,MM) (1/16/01)

Maple worksheet for Hill ciphers (2x2)

RSA.mws (DW)

Maple worksheet for experimenting with the RSA cryptosystem

The worksheets (files ending with .mws) load the cryptology programs in the file crypt.mpl. You may need to change the beginning line of the worksheet to be able to find the program file crypt.mpl to something like

read `C:/windows/desktop/crypt.mpl`;

depending on where you have put the file. Be sure to enclose the entire pathname in single backquotes.

You should be ok if all the files are in the same directory.

Last modified: January 17, 2001

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