Breaking German Army Ciphers

Five or six Easy Pieces in the key of E.

Below are six original German Army Enigma messages from 1941. The first five were originally published in our Cryptologia paper Breaking German Army Ciphers as a challenge for those wishing to attempt to break them. The second message, with the first group TAZUK, was given in error. The message ABTWU, number VI, should have been given instead. Both these messages are using the same daily settings but number II has some serious garbles in the first eleven groups and therefore may be difficult to break. Furthermore there are errors in the indicator given by the operator (SDV RUD) for this message. The other four messages were each sent on different days.

As an aid to breaking these messages, we give the bigram and trigram frequency counts that we used to break them. This is based on a number of raw message decrypts and can be downloaded here. The messages used for these frequency counts are as decrypted, with some obvious garbles removed and contain some place names. For example the trigram count for MOR, normally infrequent in German, comes from the place name MORINA used in several messages. We used the same data to break the 1945 messages described in the paper. It may be that removal of names may be of some benefit, but the messages from 1945 nonetheless broke using the 1941 data.

If anyone succeeds (or not) in breaking any of these messages, we would be delighted to know.

I - 186 - DOQ VHZ - PBNXA SMDAX NOOYH RCZGV VZCBI GIBGW HMXKR RVQCF JCZPT UNSWA DDSTI GQQCS AGPKR XXLOM GFXAP HHMRF SDKYT MYPMV ROHAS QYRWF WVAVG CCUDB IBXXD YZSAC JSYOT MWUCN WOMHH JPYWD CCLUP GSWCL MBCZS SYXPG MGMQX AUFUL NOZEQ ENHEI ZZAKL C	II - 241 - SDV RUD - TAZUK DVNNF AZOUV YYSXO ZLRJO TMMXK AWPVU TTUXS LAQOX GQUKX XKXAL URHGR SUOHD FJTRE TLFKD MGDXE MWIXX INTLG EDKVL RTJFX RFOIE NNIRR WFKTI BVFVE LLAWR GJNVB YHBZS CJVTZ PDBGV PBNNA LNAKX OUOJG WLJXO UXHDS HXJOU HVBVF DOLMN LYNVC MRGKK YTOCP DUEVN FMIPT GGJYA YBDES P
III - 149 - TLS CMU - FTMKV DRJMG FBUDK LZCTR FLTUU IWVJL OYKYX GDCKJ TMDFB WNLZQ JAXHP GGKFG SBZOQ KQKUK TINMH BAJOO AUILA QVFTK LSTMM XGAQL CNHUW LFHKA ULTXT BIVIF EWWDY PUCNS TPJHR OBWHE KYUSB CANYC W	IV - 83 - ADJ JNA - LMHNX WEKLM UERDS EVHLC JSQQK VLDES ANEVT YEDGI ZQDOD RMDKG SXGSQ SHDQP VIEAP IENLI CLZCL LAGWC BJZD
V - 167 - MRJ LLT - KLIBM ERJAR WMMHJ STHOY OOIQB HSSZU EOOKF TASXN XVYWE SCTCH NRNBL ZPEBH XPAQE DFNYS XHMNI HRARO UNBMD ZRZDN WTGUI UCBZN ZTFJA EKOMJ AZILN RKVFD UNIEW ILZVL KQYYJ ANKXG NNNHT EMAVD FXKAY MLWCV QDFWX LO	VI - 195 - EHW TNH - ABTWU GWDMP OGKMQ KBHGK HROUP RMYQY INHSA MWFBP CDQRG LDBFK YNXPP DIQHE AOIFQ AOLRZ ZFPDJ MCGEC TAHHQ MVUYA JIAWM WSOYU UTLEP AVZKG HJWCD LOQHW IMSTC LQDNP VCFCN FRUYR GSSJH ORQMU IFFYU WYNTA XPYIX MYTEE FTDCV EHUOA DCPLM APCAU JJYUK

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Copyright:
All rights to the material described on these pages belong to
Geoff Sullivan & Frode Weierud, © November 2005

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