The Enigma Test Message from 1930

On 8 November 1931 the German Hans-Thilo Schmidt, who was working at the cipher office (Chiffrierstelle) of the GermanArmy (Reichswehr), gave French intelligence copies of the two main Enigma instruction manuals: Gebrauchsanleitung für die Chiffriermaschine Enigma and Schlüsselanleitung zur Chiffriermaschine Enigma I. Both documents were seemingly dated 1930. English translations of these documents have survived. They are available at the British National Archives at Kew in London in the location HW25/9 together with other historical Enigma documents.

The translation of the document Schlüsselanleitung zur Chiffriermaschine Enigma I, which is entitled Directions for use of Keys on the Cypher Machine 'Enigma I, contains a test message which is used to show how to encipher and deciphermessages on the Enigma machine. Amazingly enough it turns out that this message is authentic. The message can be enciphered and deciphered without errors using the given keys, inner andouter Enigma settings, if the rotors I, II, and III are used together with the reflector, Umkehrwalze, A.

Because all Umkehrwalze A were rewired to Umkehrwalze C no such reflector has ever been found. The wiring of Umkehrwalze A was recovered by Philip Marks and Frode Weierud in 1999 and is described in their Cryptologia article which is available here: Recovering the Wiring of Enigma’s Umkehrwalze A, Cryptologia. 24(1), January, 2000, pp. 55‐66 Apart from being yet another proof that the recovered wiring of Umkehrwalze A is correct, it is also of interest to reflect on what can only be considered a serious security blunder. It seems that the German cipher office, which was responsible for this document, did not realize that this 90 letter long message could have been of a great help in recovering the Enigma wheel wiring.

The test message and the Enigma key settings are given below.

Key settings:

Wheel Order  :	II  I  III
Ringstellung :	24  13  22
Grundstellung:	06  15  12

Stecker: 1/13, 6/9, 14/22, 16/19, 20/21, 23/26
Stecker in literal form: A/M, F/I, N/V, P/S, T/U, W/Z

Enciphered message:

1035 – 90 – 341 – 
PKPJX IGCDS EAHUG WTQGR
KVLFG XUCAL XVYMI GMMNM
FDXTG NVHVR MMEVO UYFZS
LRHDR RXFJW CFHUH MUNZE
FRDIS IKBGP MYVXU Z

The message header consists of three parts: the Time Group (4 figures), the number of letters (two or three figures), and an arbitrary 3-figure group that is the system indicator informing the operator that this is an Enigma message. The first six letters of the message, here with a strike-through – PKPJX I, are the twice enciphered start position. Deciphering this at the Grundstellung, FOL, gives the message key or start position: ABL.


Ciphertext only:

GCDSE AHUGW TQGRK VLFGX 
UCALX VYMIG MMNMF DXTGN 
VHVRM MEVOU YFZSL RHDRR 
XFJWC FHUHM UNZEF RDISI 
KBGPM YVXUZ

Decrypts:

FEIND LIQEI NFANT ERIEK 
OLONN EBEOB AQTET XANFA 
NGSUE DAUSG ANGBA ERWAL 
DEXEN DEDRE IKMOS TWAER 
TSNEU STADT

Completely assembled German message:

FEINDLIQE INFANTERIEKOLONNE BEOBAQTET X
ANFANG SUEDAUSGANG BAERWALDE X 
ENDE DREI KM OSTWAERTS NEUSTADT

Rewritten German text:

Feindliche Infanteriekolonne beobachtet.
Anfang Südausgang Bärwalde.
Ende 3 km ostwärts Neustadt.

English translation:

Hostile column of infantry observed. Extends from the south
exit of Bear Woods to position 3 kilometers east of Neustadt.

Comments:

I am indebted to Ralph Erskine for giving me a copies of these historical documents.

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Copyright © 2008, Frode Weierud


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