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Taxonomy of Cryptology
Cryptology
Cryptography
Codes
Ciphers
Substitution
Monoalphabetic
Monographic
Polygraphic
polyalphabetic
Transposition
Geometrical
columnar
cryptanalysis
Rotor cipher
A Rotor machine is an electro-mechanical stream cipher device used for encrypting and decrypting secret messages.
A Stream cipher is a symmetric key cipher where plaintext digits are combined with a pseudorandom cipher digit stream (keystream). In a stream cipher each plaintext digit is encrypted one at a time with the corresponding digit of the keystream, to give a digit of the cipher text stream.
Monoalphabetic vs. Polyalphabetic
Monoalphabetic cipher uses fixed substitution over the entire message.
Polyalphabetic cipher uses a number of substitutions at different positions in the message, where a unit from the plaintext is mapped to one of several possibilities in the cipher text and vice versa.
Example
Assumptions:-
A rotor which is designed for first 7 alphabet.
Plaintext of length 5.
Upward rotation.
Example
A B C D E F G
A 0 0 1 0 0 0 0
B 0 1 0 0 0 0 0
C 0 0 0 1 0 0 0
D 0 0 0 0 1 0 0
E 1 0 0 0 0 0 0
F 0 0 0 0 0 0 1
G 0 0 0 0 0 1 0
Starting Configuration Of Rotor
Example
A A A A A A A A AA
B B B B B B B B BB
C C C C C C C C CC
D D D D D D D D DD
E E E E E E E E EE
F F F F F F F F FF
G G G G G G G G GG
Rot. 1 Rot. 2 Rot. 3 Rot. 4 Rot. 5
Enigma Technology
• Typewriter style cipher machine was a major advance in ease of use and cryptologic strength
• Innovation was the electro-mechanical rotors
• Rotors turn odometer style, giving a new cipher algorithm for each letter in a message
• No printing capability
Plugboard
• The Enigma machine had several cables with a plug at each end that could be used to plug pairs of letters together.
• If A were plugged to B then, on typing the letter A, the electric current would follow the path that was normally associated with the letter B, and vice versa.
Rotors & Reflector
• First rotor rotates each time a character is input.
• The second rotor rotates once each time the first rotor makes one full turn.
• The third rotor rotates once each time the second rotor has rotated completely.
How it works?
Light Panel
Keyboard
ReflectorLeft
RotorMiddleRotor
RightRotor
EntryDrum
Q W E R T Z I OU
Y X C V B M LN
S D F G KJ
Q W E R T Z I O
Q W E R T Z IU
S D F G KJ
S D F G
P Y X C V B M L
P Y X C V B M LN
P
N
KJ
O
O
M
F
Plugboard
P
A
+
-
+
M
O
- B
A
T
T
E
R
Y
HA
ON
J
X
BF
JB
P ONX
MM
AA
U
H
HH
Copyright © 2016 CipherMachines.com and EnigmaMuseum.com
Enigma rotor and reflector table
They pick any three rotors and one reflector out of these on daily basis.These are the initial configuration of those rotors and reflectors.
How many possible keys are there when you swap each letter of the alphabet with another letter?
26*25*24*23*22*21*20*19*18*17*16*15*14*13*12*11*10*9*8*7*6*5*4*3*2*1
=26!
= 400 000 000 000 000 000 000 000 000
FACTS:
400 septillion keys!
6.5 BILLION PEOPLE IN THE WORLD
31 MILLION SECONDS IN A YEAR
IF EVERYONE IN THE WORLD CHECKED ONE KEY PER SECOND, IT WOULD STILL TAKE 2 BILLION YEARS TO CHECK THEM ALL!
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