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Go through the first three chapters of the “Birth of cryptography” upto and including “Mechanising secrecy” 

	Crack the crypted text of you fellow student using the Vigen`re cipher tool
	Go through the previous two steps again, this time using a cipher of your own choosing

I gave Berry two cipher to crack. one is Vigen`re, the other one is ROT +2, forgot to put ROT on the log. Please kindly find below the ROT 

icw-umpb-sqcb-gl-tgeclcpc-gq-emmbbyw-rfgq-ayl-kyic-rfgleq-ksaf-cyqgcp-dmp-wms

clear text 

key-word-used-in-vigenere-is-goodday-this-can-make-things-much-easier-for-you

Berry complained that the keyword I used in viginere is too short so I mailed him a new cipher with new key. That's why the keywords don't match each other.

Enigma key space calculation
We have to take into account several variables.

  1. number of used rotors/number of total rotors (nr=rotor used/n=total rotor)
  2. original position of each used rotor (26^nr)
  3. kickover point of the number of used rotor - 1 (26^(nr-1))
  4. wiring on plugboard (m=number of wires, n=26 which is the number of sockets. The number of ways of choosing m pairs out of n objects is 
    (n!/((n-2m)! m! 2m))

The amount of keys is calculated like this:

varDescriptionPossibilities
a= 3 rotors used out of 4 rotors in total (it is actually 4*3*2, but the result is the same): 4!
b= 3 rotors with 26 starting positions: (26)3
c= Kickover positions of 2 rotors: 262
d= 10 plugs for 26 holes: 26!/((26-2*10)! * 10! * 2 * 10)
Total possibilities: a*b*c*d