Cryptology Lab at the 2011 CSU-P MathSciFest

Outline

1. Introduction
   1. terminology
   2. many historical anecdotes
      • Mary Queen of Scots and Francis Walsingham
      • the Zimmermann telegram
      • the Enigma machine and Alan Turing
      • Purple, the attack on Pearl Harbor, and Admiral Yamamoto
      • for much more history, see some of the references)
2. Cutting-edge Spartan encryption from ca. 7th century BCE — the scytale, a transposition cipher
   1. encryption
   2. decryption
   3. cryptanalysis
3. Julius Caesar needs to communicate with his generals: the Caesar Cipher, a substitution cipher
   1. encryption; encrypt, with key "D"=3
      • THISISATESTTHISISONLYATEST
   2. digression on modular arithmetic
   3. decryption
   4. here's a tool to make the work easier
   5. cryptanalysis; decrypt — you figure out the key!
      • rkzyykkolckigtjkiujk
      • here's a useful tool
      • cxknxawxccxkncqjcrbcqnxdnbcrxwfqncqnacrbwxkunarwcqnvrwmcxbdo
        onacqnburwpbjwmjaaxfbxoxdcajpnxdboxacdwnxacxcjtnjavbjpjrwbcj
        bnjxocaxdkunbjwmkhxyyxbrwpnwmcqnv
      • abbaevatfbhgnjnfcznxvatnabzvabhffbhaqnfbh
        aqnxvagbnoxynkbabengbpfvasyvgfnobhg
4. Kerckhoff's Principle = Shannon's maxim = "The enemy knows the system" ... as opposed to "Security through obscurity."
5. the Vigenère cipher, invented in Europe in the 16th century, unbroken for about 400 years.
   1. encryption
   2. decryption
   3. cryptanalysis; decrypt — you figure out the key!
      • jxnkrxkvvmrwyrrgqxnobkvgtmbwrvbwrmubffrlfttx
      • zstyyezmzzqwfmsefmaroezfqgmpxipvqexwomqroiujuxoezraxnipiyszwf
   4. a useful tool (or another one)
6. Public-key cryptography
   1. RSA: implementation one or two
   2. digital signatures
   3. certificate authorities in the news

hints

• the famous ETOAIN SHRDLU, and friends
• some interesting text
• more text