Note: The Input Text area is editable; that is, you can enter text into it, edit that text, paste into it, etc. On the other hand, the Output Text area is not editable; you cannot enter text into it directly. However, you can select text from the Output Text area and copy from that selection. You can use the standard Ctrl/A and Ctrl/C key combinations to select the entire contents of the area, and copy those contents into the paste buffer, respectively.
4. Next, download from CANVAS the ciphertext “ciphertext_hw2_sp23”:
o In this ciphertext, I have retained the original word spacing, punctuation, etc.
Note: In Internet Explorer, you should right-click on these links, and choose “Save Target As…”. This way, you prevent Internet Explorer from trying to put HTML tags around the files when you save them.
5. Bring this ciphertext up in an editor (a plain text editor, not something like Microsoft Word)
6. Copy all of the ciphertext from your editor and paste it into the Input Text area of the Java tool.
7. You can now use the Java tool to determine letter frequencies and come up with a first approximation of the substitution table, based on those frequencies. Also, try: http://www.richkni.co.uk/php/crypta/freq.php
8. Translate the text, based on the auto-generated table, and see if you can see anything that resembles recognizable plaintext.
9. Using the tool, change individual letter substitutions until you believe you have the complete plaintext.
Hint: You will probably find that you will have to look at the generated “plaintext” and make educated guesses at what the words might be, using clues like partially-formed words, punctuation, and a knowledge of the common two-letter and three-letter words that exist in the English language. If you get stuck, talk to someone else — your wife, husband, girlfriend, boyfriend, parents, friends, etc. It is often the case that when you get stuck, just interacting with someone can lead you to overcome the problem, even if the other person doesn’t actually come up with the solution.
Note: Just tell me where the text comes from, who the author is, etc.
10. Copy the plaintext from your Output Text area (Ctrl/A, followed by Ctrl/C), and paste it back into a new document in your editor.
11. Print the result (the plain text you found) from your editor, or copy and paste it into your Homework-2 assignment report.
What to Submit in your individual Homework-2 Report:
First, refresh your knowledge of what I expect in an assignment report (and the format of that report).
I want to see the following:
1. Answers to all the questions 1-2-3 I pose, above.
2. A description of what you did. Cite the tools that you used.
3. Your results of deciphering the “ciphertext_hw2_sp23” (the file is available from CANVAS). Include the substitution table (“map”).
While it would be nice to see you come up with a correctly deciphered result in each case, I am much more interested in a detailed description of what you did, what you tried, what worked, and (especially) what didn’t work, what your thought processes were, your frustrations, any suggestions you might have for improvements to the tool, and so on. How hard was it to solve these ciphers? How much work did you have to contribute, compared to what the tool contributed?
Be sure to give credit where it was due, to all resources (human or otherwise) you used to solve these problems.
_______________________________
* The assignment idea was offered originally by Dr. Bryan J. Higgs.
REFERENCES:
1. Tom Linton. Course on Cryptography. Java Applets. Retrieved from http://pages.central.edu/emp/LintonT/classes/spring01/cryptographyframeset.htm
2. Decrypting Text – code breaking software: Frequency analysis. Online: http://www.richkni.co.uk/php/crypta/freq.php