Alice sends the following encrypted message to Bob. Trudy gets a copy and wants to find out what it's all about. All she knows is that it is a columnar transposition cipher and is in english. As it turns outs, this is enough for her to decode the message. Can you use the above information to decode the message? Give the decoded message and explain how you went about doing the decoding. The message is broken into blocks of five for readability; there are no spaces in the original message. (Look up page 584 of the Computer Networks book by Tanenbaum for an explanation of the columnar transposition cipher).
utipo ehfrs aweyi ttumh sedpr xoati
kuuoe hrtlt cdees iehlr cfnw
Cyber Video, a popular video store, decides that they want to allow their customers to do purchases online. They decide to outsource the work to Trudy. Trudy is to write a browser based application that allows the customers to browse the store's database, make purchases and fill in payment details. Customers can pay for their purchase online using credit cards, or can choose to pay in person at the time of collection. Diagram a design of such a system. Show the essential components of the design at the client (customer) end and at the server (Cyber Video) end. What functions should be done at the client end and at the server end? Would it be advisable to use mobile code to do some of the functions? If so, which functions and why? How would Trudy ensure that information is transmitted securely? How would authentication be done? Give a brief explanation of how the whole system works. What are the security issues involved here?
This one is a reading assignment. In your own words, write a short essay (3-4 pages; approx 1000 words max) on the key issues in electronic commerce today. You can use Roger Clarke's paper Key Issues in Electronic Commerce and Electronic Publishing as a starting point. List all reference material that you make use of. Provide links to online references.
Submit the solution to question 1 in a file called
cipher.html, that to question 2 in a file called
video.html, and that to question 3 in a file called
issues.html. The above three files, and any
additional files that you create as part of your report, should all
be in the same directory. Links to files that you have created
should be relative links of the form
href="next.html", so that they will work even
when the files are relocated. All diagrams/images should
also be submitted as well, in the form of
JPEG or GIF files. Submit all your files
using the submission tool.
Files you have found on the Internet should NOT be submitted as your work; your documents should have URL links to the external documents. You should avoid copying or closely paraphrasing material from the documents that you find, including those of your friends (that's plagiarism). If you feel it necessary to include material from someone else's document, then it should be clearly identified as such, identifiable as quoted material by layout or quotation marks, and proper attribution made.
Last modified: Mon May 24 10:08:43 EST 1999
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