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Better Know Cryptography History

John Downey
September 26, 2011

Better Know Cryptography History

John Downey

September 26, 2011
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  1. ¡  Used  transposition   ¡  Not  very  complex   § 

    Most  people  couldn’t   read  anyway   ¡  Caesar  cipher  (shift  3)   §  Hello   §  Khoor   ¡  ROT-­‐13  
  2. ¡  A  type  of  polyalphabetic   cipher   ¡  Confederacy

     used  during   the  Civil  War   ¡  Used  a  repeating  key   ¡  Example   §  ATTACKATDAWN   §  LEMONLEMONLE   §  LXFOPVEFRNHR  
  3. ¡  Used  by  Nazi’s  during   World  War  2  

    ¡  Was  another  type  of   polyalphabetic  cipher   ¡  One  or  more  rotors   would  tweak  settings   ¡  Each  rotor  changed  daily   ¡  Allies  eventually  broke   the  code  
  4. ¡  Based  on  really  hard  math   problems   ¡ 

    One-­‐way  hash   §  MD5,  SHA1,  etc   ¡  Symmetric  cipher   §  Works  with  a  shared  key   §  DES,  Blowfish,  AES,  etc   ¡  Asymmetric  cipher   §  Works  with  public/private   keys   §  DSA,  RSA,  etc