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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.
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
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.
GCDSE AHUGW TQGRK VLFGX UCALX VYMIG MMNMF DXTGN VHVRM MEVOU YFZSL RHDRR XFJWC FHUHM UNZEF RDISI KBGPM YVXUZ
FEIND LIQEI NFANT ERIEK OLONN EBEOB AQTET XANFA NGSUE DAUSG ANGBA ERWAL DEXEN DEDRE IKMOS TWAER TSNEU STADT
FEINDLIQE INFANTERIEKOLONNE BEOBAQTET X ANFANG SUEDAUSGANG BAERWALDE X ENDE DREI KM OSTWAERTS NEUSTADT
Feindliche Infanteriekolonne beobachtet. Anfang Südausgang Bärwalde. Ende 3 km ostwärts Neustadt.
Hostile column of infantry observed. Extends from the south exit of Bear Woods to position 3 kilometers east of Neustadt.
I am indebted to Ralph Erskine for giving me a copies of these historical documents.
Copyright © 2008, Frode Weierud
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