COMP 4140 Introduction to Cryptography and Cryptosystems

September to December 2011 - Supplementary Material

• Course Notes here.
• An interesting article about the new breaking of an old cipher is here
• The numbers that go with the Vigenere example (second part) can be found here.
• Corrections to lecture Sept. 16 can be found here.
• Cory found an URL for the lipogram Gadsby.
• Here is the the challenge cryptogram.
• A student (DS) found an interesting site dealing with civil war ciphers at Vicksberg at this url .
• A student (TH) found a very interesting site dealing with spies and ciphers (They call them codes). It takes 10 minutes to read it and it is here.
• A student got hold of a French lipogram and calculated the Index of Coincidence. The student had to worry about case abd accents. The student had to get the Index of Coincidence in French. Further the student had to recalculate it as they used a different formula. Finally, the student got the index of coincidence of the novel and got a value very close to the theoretical one. It seems that a novel that just happens to have no e's in it, does not change the index of Coincidence all that much. Why is that? Think about it. The results page is here .
• Cryptanalysis of Substitution Cipher from Stinson
• Cryptoquote for the first class. Cryptoquote for Sept. 24. Cryptoquote for Nov. 19.
• A comp4140 student recommends the following book as an interesting read. You have to buy the book but here are some descriptions about it. It is a book entitled "Cryptonomicon" by Neal Stephenson.  Some of things we talked about in class come up in it, including several ciphers and how they can be broken.  It also contains details about WW2 enigma machines, and some other interesting means of espionage like Van Eck Phreaking.  I just mention it because while it is a scifi/historical fiction book, it revolves around code breaking (for the most part) and gets pretty technical about it, so it may be of interest to 4140 students. Here's a couple links that do a much better job describing the book: here and here
• A comp4140 student looked up the Sherlock Holmes story and analized the "pig-pen-like" cipher in it. Read it and enjoy.
• Here is a brief joke history of AES and a how-to-code-it-for-dummies here
• Here are more frequencies of letters including double letters:here
• A good piece on quantum cryptography (easy to readand up to the minute) has been found by one of the COMP4140 students. Take out 5 minutes and read this article .
• Here is an interesting article on hashing using MD5 and the dangers thereof in here
• The FIPS document for SHA-1 is here
• There are two interesting web-sites on cryptographic hashing here and and here
• Here is an interesting paper on Chosen-Ciphertext Attacks on e-mail encryption Protocols in here.
• Here is an interesting article on psuedo-random number generators and how they relate to ciphers in here
• Here is a good entry for the USSR twice use of one-time pads Don't they understand the word one in one-time pad
• Some examples of trails Some more examples of trails
• Cryptoquotes here, here and here.
• Link to a wonderful history of Cryptography. Just read the interesting accounts for their enjoyment. Codes, Ciphers & Codebreaking by Greg Goebel
• Link to a word document of a previous year's midterm
• Link to a word document of a previous year's midterm solution
• Link to a word document of a previous year's exam
• Link to a cryptanalysis of the substitution cipher in Stinson's book example 1.11
• Stinson's Vigenere example page 34 here.
• Link to Howard M. Heys'" "A Tutorial on Linear and Differential Cryptanalysis
• Some statistics from the Gadsby.
• Link to AES document (FIPS 197) Postscript or PDF
• Frequency distributions of English letters, digraphs, and trigraphs (Postscript or PDF)