CS551: Security and Privacy on the Internet, Fall 2000
Manifest: Monday 4 September 2000
Assignments Due Monday, 11 September Problem Set 1 Monday, 18 September Projects Preliminary Proposal
ReadingsRead before 6 September: Stallings, Chapter 3.
Optional reading for more information: (see web version for links)
- Claude Shannon, Communication Theory of Secrecy Systems, 1949. (Original paper as images.)
- Alex Biryukov's lecture notes on cryptanalysis of Enigma
- Alan Turing's Treatise on Enigma (1940, declassified in 1996)
- Breaking the Code (1997 movie with Derek Jacobi)
1 2 3 4 5 Count: 12345678901234567890123456789012345678901234567890123456 Plain: ThebiggerboysmadeciphersbutifIgotholdofafewwordsIusually Key: KEYKEYKEYKEYKEYKEYKEYKEYKEYKEYKEYKEYKEYKEYKEYKEYKEYKEYKE Cipher: DLCLMEQIPLSWCQYNIASTFOVQLYRSJGQSRRSJNSDKJCGAMBHQSYQEEJVC 6 7 8 9 10 11 7890123456789012345678901234567890123456789012345678901234 Plain: foundoutthekeyTheconsequenceofthisingenuitywasoccasionally Key: YKEYKEYKEYKEYKEYKEYKEYKEYKEYKEYKEYKEYKEYKEYKEYKEYKEYKEYKEY Cipher: DYYLNSSDXFOOCIXFOGMXWCAYCXGCYJRRMQSREORSSXWGEQYGAKWGYRYVPW 12 13 14 15 16 5678901234567890123456789012345678901234567890123456789 Plain: painfultheownersofthedetectedcipherssometimesthrashedme Key: KEYKEYKEYKEYKEYKEYKEYKEYKEYKEYKEYKEYKEYKEYKEYKEYKEYKEYK Cipher: ZEGXJSVXFOSUXIPCSDDLCNIROGROHASTFOVQCSKOXGWIQDLPKWFOHKO 17 18 19 20 012345678901234567890123456789012345 Plain: thoughthefaultlayintheirownstupidity Key: YKEYKEYKEYKEYKEYKEYKEYKEYKEYKEYKEYKE Cipher: XFYYERXFOJYEPRVEWSRRRIGBSUXWRETGNMRI
Charles Babbage (quoted in Simon Singh,
The Code Book : The Evolution of Secrecy from Mary, Queen of Scots to Quantum Cryptography, 1999)
- How to attack the Vigenere cipher.
- How do you convince someone a cipher is secure?
- What is a "perfect cipher"?
- How to prove a cipher is perfect.
- How to prove a cipher is imperfect.
- What are entropy, rate, redundancy, and unicity?
- How important is redundancy in cryptology?
Propose to an Englishman any principle, or any instrument, however admirable, and you will observe that the whole effort of the English mind is directed to find a difficulty, a defect, or an impossiblity in it. If you speak to him of a machine for peeling a potato, he will pronounce it impossible: if you peel a potato with it before his eyes, he will declare it useless, because it will not slice a pineapple.
Charles Babbage, breaker of Vigenere cipher, after losing funding for his Difference Engine project, 1823.
University of Virginia
Department of Computer Science
CS 551: Security and Privacy on the Internet