Station X April
23, 1940
Dear Paul,
Our navy has captured an enemy ship. Inside were
discovered Enigma documents, including a message
encrypted with the corresponding plain text.
Indicator: LGZU SUQC
abcd efgh ijkl mnop qrst uvwx yzab
GEBE NXSI EXIH REXP OSIT IONX ANXX
JNJN MGUD KBKW FGHL XRMQ OPKL BEWM
ADMI RALX KARL XDOE NITZ
XXIH EQDQ IZGX ZHCS TOIV
From this we made a menu for our bombes. We got the
following stop:
Walzenlage: VI-III-II, Rotors position: CBV
Machine gun: BH DD EJ FL GO HB II JE KN MM NK OG
RY ST UW WU XX
Steckers (8): BH, EJ, FL, GO, KN, RY, ST, UW
If we try to decipher at the stop position CBU (in
fact one position before CBV because the rotors steps
before the cipherment) with ringstellung AAA.
1 2 3 4
012345678901234567890123456789012345678901234567
GEBENXSIEXIHNRDYAKFEZJGXPNXXPDMIRILVURNCNRDXRRFJ
GebenXSieXIhreXPositionXanXXAdmiralXKarlXDoenitz
At position 28, we can deduce a new stecker: PA
If we try the AAM Ringstellung (so the position of
the rotors must be CBG), we get the following decryption:
GEBENXSIEXIHREXPOSIBIONQANXXADMIRILVKBRLSDOENITQ
GebenXSieXIhreXPositionXanXXAdmiralXKarlXDoenitz
At position 47, we can deduce the last stecker: QZ
If we try several Ringstellung, we finally find the
good one: AAN. With it, we decipher correctly the
message. In this case, the start position of rotors is
CBH (CBV+N=CBH).
All steckers: RY:JE:OG:HB:NK:TS:UW:PA:QZ:FL
GEBENXSIEXIHREXPOSITIONXANXXADMIRALXKARL
XDOENITZ
Now we create the
EINS catalog. EINS is calculated
for each position of the rotors.
We are now able to find the key to the following
five messages:
HDKF KLGB MCAI QYVV XIZN QXSE XUVG VPXT
HGUY EWHA GZHH PSCT VSAU XNPX HJZX HDKF
KLGB
GYTZ NCXN CPWL AHML KGBX UOQW WGYK XVYZ
QENS HLUG VAMX GYTZ NCXN
MQKM YYQW XSXA RSLS HGLX KPJK YSAO TFVM
TVSZ QRHD MPCJ KGXF HQJA NVKE GMQH ZZWX
MQKM YYQW
DRCN INWF UTXO PDAT OLHF WPDH HCTU ABKH
YJTP YDCL ACKT FKXX DRCN INWF
KFOU OJXQ IFYF EMZQ SXJJ YOXZ XEPN RPEU
EWLA JOLE KFOU OJXQ
Hug Alexander
