From Caesar to Modern Cryptography







Vini, Vidi, Vici
Julius Ceasar 100BC - 44BC











 
    
Tell Cleopatra,
WE ATTACK AT DAWN!

                                               





Leave it to me sir!
Sgt. Pony 50BC-48BC

                         
                                  
   Attack at dawn!             ATTACKATDAWN                                           




  I was never really on your side!
     Sgt. pony 50BC-48BC      





                                             
      They attack at dawn!                                 oh yea
                                                                       


What Caesar did

       abcdefghijklmnopqrstuwxyz

caesar_cipher("ATTACKATDAWN", 5)



We get, fyyfhpfyifbs










                                   Attack at dawn!                     fyyfhpfyifbs            Attack at Dawn!
                                       




Symmetric Pre-shared Keys








   Vigenère cipher



Cipher analysis





The use of cryptography was obscure









World War II 
(1939 - 1945)



The German Enigma Machine




Alan Turing
(1912-1954)



Bombe vs The Enigma 

      Modern day 

   

        




Key distribution problem


                      

  1. Availability
  2. Scalability


Diffie-Hellman Key Exchange

             Experiment!

  1. Find a partner
  2. paint a small square with a yellow highlighter
  3. pick up a highlighter of another color
  4. color over the yellow square 
  5. trade your colored square with a partner
  6. receive your partner's colored square
  7. color over your partner's square with your highlighter
  8. get same colored square as your partner!



RSA 




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(It's a minute long)

 


Summary



         Plain text             -->     Caesar Cipher

         Caesar Cipher          -->     Vigenere cipher

         Vigenere Cipher        -->     RSA (public key infrastructure)


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