ECT 250: Survey of e-commerce technology

Assignment 8


Read Chapters 6, 8, 9, and 11 in Electronic Commerce.


This assignment asks you to investigate the Vigenere cipher.  Find enough information to answer the questions below:

  1. [10 points] For whom is the cipher named?  Who was he, when did he live, and what was his nationality?
  2. [30 points] What is the Vigenere cipher?  Define the terms given below.  How are each related to the Vigenere cipher?  Give a clear and specific answer for each one.
    1. Simple substitution cipher
    2. Caesar cipher
    3. Gronsfeld cipher
  3. [20 points] When referring to ciphers, what is a frequency analysis?  Is the Vigenere cipher more or less vulnerable to a frequency analysis than a simple substitution cipher?  What property does the Vigenere cipher have that simple substitution ciphers do not?
  4. [20 points] Give the Vigenere tableau.  You may attach a printout if you wish.
  5. [20 points] Use the Vigenere cipher to encode the sentence: 


Use your last name as the keyword in encoding the message.  Break up the answer into blocks of 5 letters each.  (Why not just leave the words intact?  What is the security benefit?)  Submit that name as part of the answer to the question.  Explain how you did the encoding.  Be detailed and clear in your explanation.  A good answer to this question will include a step-by-step description of how the encoding was done.

Note: You must do this part of the assignment by hand.  You may use a program to check your answer, but you may not use one to produce the answer.  Any answer to this question that does not have a written explanation of how the answer was produced will receive a 0.  Any answer that involves the use of a program will receive a 0.

You must include a bibliography indicating where you obtained your information.  Remember that directly copying from a source is considered plagiarism.  Cite your sources and put the information you find into your own words.

Submitting the assignment

To submit the assignment you may:

  1. Bring the assignment to class.
  2. Fax the assignment to me at (312) 362-6116.  Be sure to either use a cover sheet with my name on it or write ECT 250 and my name prominently on the top of the first page.  I will not be responsible for lost faxes if you do not do so.
  3. Drop off the assignment at 243 S. Wabash, room 401.  Make sure that they time-stamp your assignment.

E-mail submissions will not be accepted.