Dear Students,

In order for you to see what is a pre-image attack against a cryptosystem, I would like to ask you to watch one of the movies about the cryptosystem "Enigma". There are

"Enigma" (2001),

http://en.wikipedia.org/wiki/Enigma_%282001_film%29

"Codebreaker"

http://en.wikipedia.org/wiki/Codebreaker_%28film%29

"The Imitation Game",

http://en.wikipedia.org/wiki/The_Imitation_Game

If you have watched any of these in recent years, then you can disregard this.