German Army Enigma Keys
for July 1941, Batch B.

After publishing the German Army messages from July 1941, Batch B, we decided to try to break some of these messages which we earlier never attempted to break. So far we have recovered the keys for nine days and we continue to work on some of the remaining messages and keys. Instead of waiting until all the messages have been cleaned up and put into a format suitable for publishing, we have decided to release the Enigma keys first. In this way those of you who wish to hone their decoding skill have the opportunity to work on the real messages including garbles and other errors. We are convinced this will be a unique learning experience for those who want to get a feeling for what went on in Hut 3 at Bletchley Park during the Second World War.

As we mention on the Web page with the messages from Batch B, some of the messages from a given day sometimes belong to the previous day. The example we mention is Nr. 157, ABUNY, which was received at 01:00 on 10 July 1941, but where the header shows that the message was prepared at 23:13. As expected this message has been enciphered on the key from 9 July 1941. Instead of rearranging the messages to their correct date we leave them as shown on the message forms. However, we group all corresponding messages under their correct daily key.

For the readers who would like to try their decoding skills we should like to mention a few important point. You can use any Enigma simulator that has been certified to be correct in the sense that it uses the correct wheel wiring and also very important, that handles the Enigma stepping correctly. First of all you have to set up your Enigma machine with the correct wheel order and Ringstellung. You then have to make the Stecker connections for that day. You are now ready to decipher a message. In the Enigma keys below we also give the message key, the starting position. You find the corresponding message keys under the column, Start. However, to get a real feeling for it you should recover the message key yourself by first setting the machine to the Grundstellung, the first group of the indicator, and then decipher the second group of the indicator. As an example we will take message Nr. 101, DEROP, of 5 July 1941. Here the indicator is the two 3-letter groups, AIK SUD. Setting the Enigma wheels to AIK you then decipher the second group, SUD, which will give you WER. You then set your Enigma machine to the starting position WER. You are now ready to decipher message Nr. 101. The message starts: DEROP AQDEG MQTRR JYMHB, but the first group, DEROP, does not belong to the cipher text. It is the discriminant, Kenngruppe, which tells the cipher operator which Enigma key has been used to encipher this message. You therefore have to start deciphering the from the second group, AQDEG. From here you are on your own. We wish you the best of luck.

For further information about our codebreaking project see our Web Portal: Breaking German Wehrmacht Ciphers.

1 July 1941

Enigma keys for 01.07.1941

UKW : B W/O : 423 Stecker : CT, EM, FI, GJ, HK, NQ, OR, SW, UY, VX Rings : (AAV) Message keys: No: Part: Kenngruppe: Indicator: Start: Stop: 73 LYASO TCR IEI KFU 1) Notes: 1) The indicator TCR IEI or the most likely variations of this indicator does not give a credible Ringstellung.

5 July 1941

Enigma keys for 05.07.1941

UKW : B W/O : 354 Stecker : BI, CW, EQ, FX, HZ, JN, KY, MT, OV, PR Rings : WHJ Message keys: No: Part: Kenngruppe: Indicator: Start: Stop: 99 XTMSY QCB NSR SIM SOM 100 LXACA OGD PKN 1) 101 DEROP AIK SUD WER WLN Notes: 1) This message which was received at 04:45 but carries the time 23:40 in the header is probably from the previous day, 4 July 1941. The message does not break on the key for 5 July 1941.

7 July 1941

Enigma keys for 07.07.1941

UKW : B W/O : 245 Stecker : AV, BS, CG, DL, FU, HZ, IN, KM, OW, RX Rings : BUL Message keys: No: Part: Kenngruppe: Indicator: Start: Stop: 113 XIVFG LMN JGO OPQ OQQ

8 July 1941

Enigma keys for 08.07.1941

UKW : B W/O : 432 Stecker : CY, EL, FH, GS, IJ, KQ, MW, PV, RZ, TU Rings : PKF Message keys: No: Part: Kenngruppe: Indicator: Start: Stop: 122 GLPTL WCK KLN KLW YXC YAR 126 ABDJV ACS GUT XEL GUT HDX 127 HBNVE DRU QBP TRE UXH

9 July 1941

Enigma keys for 09.07.1941

UKW : B W/O : 315 Stecker : AC, BN, FM, GI, JL, KO, PU, QX, RZ, TV Rings : NAV Message keys: No: Part: Kenngruppe: Indicator: Start: Stop: 136 CASBL JOL ROH LRU LAU LDS 1) 138 WEUWY NUG YKI 2) 139 BEYWU MIN MER ALA ANI 140 WEUWY NIG IKS 2) 141 DESGF GMD NQZ HNM HPX 142 TUGFI NOV ANZ HBN HDF 143 WNFGI BIW CRF RFV RIC 153 SOFGI HMR ECH OFF 3) 157 ABUNY EUQ MAC SIM SNQ 158 NEWUY OPB LAB KFK KKA 160 ENIDN UFZ AGE WUK WZE Notes: 1) Nr. 136, CASBL, is missing four groups, twenty letters, in the beginning of the message. The given start position, LAU, is for such a message padded with twenty random letters or three groups of hyphens in the beginning. Our Enigma simulators will function correctly with cipher text containing hyphens. The simulator will then step correctly while inserting a hyphen in the plain text. 2) Nr. 138 and 140, both with Kenngruppe WEUWY, does not seem to break on this key. 3) Nr. 153, SOFGI, gets garbled after the third cipher group. No fiddling seems to decode the following cipher groups.

10 July 1941

Enigma keys for 10.07.1941

UKW : B W/O : 521 Stecker : AS, BG, CK, DZ, IO, LR, MP, QT, UW, VY Rings : JQH Message keys: No: Part: Kenngruppe: Indicator: Start: Stop: 161 ANIJQ IPG PHA ZOR DOR DVP 162 1tl ABNAQ DVP TDB ERT EZU 162 2tl RDNAQ FGH XVX GHJ GMS 167 BIOQN PYV EKJ VBN VDJ 168 SHNQO VDJ RSJ VFR VJB 170 TXIJQ CIJ UWH TGB TKP 172 MVUEH GTA KCI 1) 173 SIPVX SWV YTE 1) 176 RLGRZ BDF PNX WER XJC 180 NZGRZ ALO XGF BOI BQR Notes: 1) Nr. 172 and 173 do not break on this key. It is therefore suspected that these two messages are from a different network and that they are on a different key.

13 July 1941

Enigma keys for 13.07.1941

UKW : B W/O : 423 Stecker : AD, EH, GY, IM, KN, LR, OZ, QV, TX, WU Rings : GTO Message keys: No: Part: Kenngruppe: Indicator: Start: Stop: 197 ANERF QCV MLN 1) 199 MYFRE XIC YUU TGB THE 200 GSEAN NTO BTU MXK MAO 201 EGERF OLG ANW IJN IOF Notes: 1) Nr. 197, ANERF, is probably a dud but it fails dudbusting.

18 July 1941

Enigma keys for 18.07.1941

UKW : B W/O : 425 Stecker : DM, EP, FL, HI, JR, KY, NQ, OU, SW, TZ Rings : AGM Message keys: No: Part: Kenngruppe: Indicator: Start: Stop: 228 HJVVS UKM IUX AKF AQG

25 July 1941

Enigma keys for 25.07.1941

UKW : B W/O : 325 Stecker : BE, CK, DL, GM, HZ, JO, NW, QU, RT, SV Rings : RVA Message keys: No: Part: Kenngruppe: Indicator: Start: Stop: 266 AJLJD FQT YSB IDA JKS

All rights to the material described on these pages belong to
Geoff Sullivan & Frode Weierud, © April 2006

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