(Chapter 2: Classical Encryption Techniques)
Total Marks: 10
Due Date: January 19th, 2010, by Midnight EST
Answer any two. If you can solve all three, you will get 5 points extra.
1.
Encrypt the message “meet me at clock tower at ten” using the Hill
cipher with the key
Show your calculations and the result. 5 points
2. The book shows that the Hill cipher can be broken by a known plaintext attack if there are sufficient plaintext-ciphertext pairs. Can you solve Hill cipher with chosen plain text? If yes, then describe such an attack. 5 points
3. In one of his cases, Sherlock Holmes was confronted with the following message:
534 C2 13 127 36 31 4 17 21 41
DOUGLAS 109 293 5 37 BIRLSTONE
26 BIRLSTONE 9 127 171
Although Watson was puzzled, Holmes immediately deduced the type of cipher. Can you do it too? (Problem 2.6 from the text book) 5 points