ENTITY // M4 TEST BENCH

Enigma M4 Simulator

READY

How to use

Set the Umkehrwalze (reflector) and Zusatzwalze (Greek rotor).
Set the three moving rotors in Walzenlage, from left to right.
Enter Ringstellung and Grundstellung as 4 letters in this order: Greek · Left · Middle · Right.
Enter the Steckerbrett as space-separated pairs, for example AG BX CR DV. Leave it blank for no connections.
Paste the message. Spaces, numbers and punctuation are ignored: the M4 processes A–Z only.
Press Run M4. Decryption uses exactly the same operation, starting again from the same initial configuration.

The rotors step before each letter is enciphered. The Beta/Gamma Zusatzwalze remains stationary. The simulator also implements double-stepping.

Machine configuration

Umkehrwalze Zusatzwalze

Walzenlage — moving rotors, left → right

Left Middle Right

Ringstellung 4 letters: Greek · Left · Middle · Right Grundstellung 4 letters: Greek · Left · Middle · Right

Steckerbrett

Message

Input

Output

0 letters Final windows: ----

Maintenance test

The Load TEST_VECTOR button loads the neutral configuration defined for the game. After pressing Run M4, the result must be:

BPGANGUMQGJIPXKXS

Test not run.

Signal path

INPUT
  ↓
STECKERBRETT
  ↓
RIGHT rotor
  ↓
MIDDLE rotor
  ↓
LEFT rotor
  ↓
ZUSATZWALZE (Beta/Gamma)
  ↓
UMKEHRWALZE (B-Thin/C-Thin)
  ↓
ZUSATZWALZE reverse
  ↓
LEFT rotor reverse
  ↓
MIDDLE rotor reverse
  ↓
RIGHT rotor reverse
  ↓
STECKERBRETT
  ↓
OUTPUT

To use the simulator with E9, first verify that TEST_VECTOR produces the expected result. Then replace the parameters with those derived from the enigma files and the values recovered earlier, paste INTERCEPT.MSG, and run the machine again from its initial state.