The

The

Enig

ma

Enig

ma

Mac

hine

Mac

hine H

isto

ry o

f Com

putin

gD

ecem

ber 6

, 200

6M

ike

Kos

s

Inve

ntio

n of

Eni

gma

!In

vent

ed b

y A

rthur

Sch

erbi

us, 1

918

!A

dopt

ed b

y G

erm

an N

avy,

192

6!

Mod

ified

mili

tary

ver

sion

, 193

0!

Two

Add

ition

al ro

tors

add

ed, 1

938

How

Eni

gma

Wor

ks

Scra

mbl

ing

Lette

rs

!Ea

ch le

tter o

n th

e ke

yboa

rd is

co

nnec

ted

to a

la

mp

lette

r tha

t de

pend

s on

the

wiri

ng a

nd

posi

tion

of th

e ro

tors

in th

e m

achi

ne.

!R

ight

roto

r tur

ns

befo

re e

ach

lette

r.

How

to U

se a

n En

igm

a!

Dai

ly S

etup

�Se

cret

setti

ngs

dist

ribut

ed in

cod

e bo

oks.

!En

codi

ng/D

ecod

ing

a M

essa

ge

Setu

p: S

elec

t (3)

Rot

ors

!W

e�ll

use

I-II

-III

Setu

p: R

otor

Rin

g Se

tting

s

!W

e�ll

use

A-A

-A (o

r 1-

1-1)

.

Rot

or C

onst

ruct

ion

Setu

p: P

lugb

oard

Setti

ngs

!W

e w

on�t

use

any

for o

ur e

xam

ple

(6 to

10

plug

s wer

e ty

pica

l).

Setu

p: In

itial

Rot

or P

ositi

on

!W

e�ll

use

�M-I

-T�

(or 1

3-9-

20).

Enco

ding

: Pic

k a

�Mes

sage

Key

�

!Se

lect

a 3

-lette

r key

(or i

ndic

ator

) �at

ra

ndom

� (le

ft to

the

oper

ator

) for

this

m

essa

ge o

nly.

!Sa

y, I

choo

se �

M-C

-K�

(or 1

3-3-

11 if

w

heel

s are

prin

ted

with

num

bers

rath

er

than

lette

rs).

Enco

ding

: Tra

nsm

it th

e In

dica

tor

!G

erm

ans w

ould

tran

smit

the

indi

cato

r by

enco

ding

it u

sing

the

initi

al (d

aily

) rot

or

posi

tion�

and

they

sent

it T

WIC

E to

mak

e su

re it

was

rece

ived

pro

perly

.!

E.g.

, I w

ould

beg

in m

y m

essa

ge w

ith

�MC

K M

CK

�.!

Enco

ded

with

the

daily

setti

ng, t

his

beco

mes

: �N

WD

SH

E�.

Enco

ding

: Res

et R

otor

s

!N

ow se

t our

roto

rs d

o ou

r cho

sen

mes

sage

ke

y �M

-C-K

� (1

3-3-

11).

!Ty

pe b

ody

of m

essa

ge:

�ENIGMA REVEALED

� en

code

s to

�QMJIDO MZWZJFJR

�.!

Com

plet

e m

essa

ge is

then

:NWDSHE QMJIDO MZWZJFJR

Dec

odin

g: In

itial

Set

ting

!Se

tup

is th

e SA

ME

for e

ncod

ing

and

deco

ding

. Se

t rot

ors t

o �M

-I-T

� (1

3-9-

20).

Dec

odin

g: D

ecod

e In

dica

tor

!Ty

pe in

mes

sage

indi

cato

r: �N

WD

SHE�

.!

Con

firm

it d

ecod

es to

�M

CK

MC

K�

(a

valid

mes

sage

key

).

Dec

odin

g: M

essa

ge

!Se

t rot

ors t

o �M

-C-K

� (1

3-3-

11)

!Ty

pe re

mai

nder

of m

essa

ge:

�QMJIDO MZWZJFJR

�be

com

es�ENIGMA REVEALED

�!

A P

aper

Eni

gma

Mac

hine

!Ea

ch ro

tor i

s mod

eled

as a

strip

of p

aper

; the

el

ectri

cal c

onta

cts a

re re

plac

ed b

y m

atch

ing

lette

rs o

n le

ft an

d rig

ht si

de o

f the

strip

.!

Key

boar

d an

d La

mps

are

repl

aced

by

a ve

rtica

l lis

t of l

ette

rs o

n th

e rig

ht.

!R

efle

ctin

g ro

tor i

s rep

lace

d by

a m

atch

ing

grou

p of

lette

rs o

n th

e le

ft.!

Plug

boar

dan

d ro

tor �

ring

setti

ngs�

are

not

m

odel

ed.

Sam

ple

Enco

de

!R

otor

ord

er: I

, II,

III

!R

otor

setti

ng: M

, C, K

!En

code

the

lette

r �E�

Initi

al S

ettin

g!

Rot

ors I

, II,

and

III

!�W

indo

w se

tting

s� o

f �M

-C-K

�

Enco

de a

lette

r

!(F

irst!)

Adv

ance

the

right

-mos

t rot

or (I

II) b

y m

ovin

g it

up o

ne ro

w.

�Man

ual�

Ele

ctric

ity

!St

art a

t �E�

on

the

right

co

lum

n.!

Trac

e th

roug

h ea

ch

roto

r, m

atch

ing

like

lette

rs.

Rol

love

r

!W

hen

the

�not

ch�

arro

w re

ache

s the

w

indo

w, m

ove

the

whe

el to

it�s

left

up o

ne

row

bef

ore

enco

ding

.!

Whe

n th

e ce

nter

whe

el a

rrow

reac

hes t

he

win

dow

, rem

embe

r to

mov

e B

OTH

cen

ter

and

left

whe

els!

Bre

akin

g En

igm

a

!Po

les i

nter

cept

com

mer

cial

Eni

gma

in th

e m

ail,

1928

!R

ecru

it m

ath

stud

ents

at P

ozna

n U

nive

rsity

, 192

9!

Pole

s (R

ozyc

ki, Z

ygal

ski,

Rej

ewsk

i) br

eak

the

3-ro

tor m

achi

ne, 1

932-

1939

!O

verw

helm

ed b

y 2

new

roto

rs in

193

8!

Pole

s han

d ov

er m

etho

ds a

nd m

achi

ne c

opy

to

Brit

ish

and

Fren

ch in

193

9!

Gov

ernm

ent C

ode

& C

iphe

r �Sc

hool

� cr

eate

d at

B

letc

hley

Par

k, 1

939

Vul

nera

bilit

ies

!En

cryp

tion

of d

oubl

ed in

dica

tors

reve

als

info

rmat

ion

abou

t rot

or p

ositi

ons.

!O

pera

tors

cho

ose

poor

mes

sage

key

s (e.

g.,

�BER

�, �

LIN

�, �

HIT

�, �

LER

�, �

JJJ�

, �Q

WE�

).!

Lette

r nev

er e

ncry

pts t

o its

elf (

allo

ws

know

n pl

aint

ext a

ttack

).

US

Arm

y, M

-94

Cip

her D

evic

e

US

Arm

y, M

-209

(Hag

elin

)

Swis

s, N

EMA

(N

ew

Mac

hine

)

Hag

elin

CD

-57

Hag

elin

CX

-52

RT

(Ran

dom

Tap

e)

Rei

hens

chie

ber