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Munitions Buildings, Washington D.C.
30 November 1938
Dear Bob and Albert,
Your goal is simple: decipher the following
messages. Unfortunately the Japanese no longer
respect the separation of vowels and consonants.
I remind you that the text is in English and the
words are separated by the letter Z.
I give you several Cribs:
Z stop Z
Z comma Z
Z chinese Z forces Z
Z chinese Z collaborator Z
Z Germany Z
Z The Z Soviet Z Union Z
The three messages were intercepted in the same 10
days period and they have the same indicator: 63521
(which we removed). We can therefore deduce that
the three messages were encrypted with the same
key.
Good Luck !
Frank Rowlett
1) First message
LYJIK GGGVA BZQGV TWRIA QMALH ARPUD HADYC
KMJAV NEYAY ZFERQ XMQQN INZWO JVGJK MJMZL
OLNIJ ORJGB DFKSD JRKYD WWWGY MIGFG WMYHZ
ELINI TWELI UFSHU SABTA MVGNX IPUET ADMSJ
DEJIB XDSFF MXQME HWKGN IMKNO LVXOV AEZLO
LNINK HGOYW QTRCQ ZYTWK PVQGF BDFEW BWDUI
LDRNG AMPAP UVCTP WKOGM QNPCE PHOLI TVDDL
QSIDJ BJGRX PE
2) Second message
RALLN DRQKU TCEBX FAZEU JLNPH PJSTQ EJSVP
TASEN KPTUP ZFEON ZDTLZ HZITV CPCYU MVGZA
AQLAB UPJGR OJRRK SLHUQ WISIW OLEVR SBLZQ
EWLWC BDSQW FFSMU YFZYX IBEGF XSUGM ZMOUQ
RQQTN GKSHF VDBFD TQECL HURNX ELPRU ZXEKK
MODMU NAZPH OUMPG ZSQKJ XCQEJ GCNUC BWTKQ
RJBFN UEDVQ FTRZS PCQGP MXGVG YWFUJ MKBWK
VGERT AJVLA BERKH EK
3) Third message
YFEIJ GQVJF PUGJD JUTCU BGFRQ BVHZR UTHYN
ZKVES NWVOT UUEUD FUQHJ INOKR JUYUK JKIVK
KMNYN GAJVI WFEJH IKSQN ONDRQ ZFNYR UZCEK
KAWLG UEJAP CHQPK PBMQW XNPGH MFTHF MBFFX
QKRKA XKFVJ RGWMQ DRVZJ LWTWG FHSRT ETYLJ
UMIEO FRQIB WRUZO EKSGL XNQGF AAPMR SBDDQ
XOLKU NEPOY NTMYX PQIHE WIPHW P
Here are the letter frequencies of the messages
intercepted during the 10 days period. I think it
is possible to deduce the SIXES. These are either
the six most frequent letters or the six least
frequent letters.
A 248 0.05: * * * * * * * * * * * * * * * * * * * * * * * * * * * * * *
* * * * * * * * * *
B 157 0.03: * * * * * * * * * * * * * * * * * * * * * * * * *
C 146 0.03: * * * * * * * * * * * * * * * * * * * * * * * *
D 221 0.04: * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * *
* *
E 205 0.04: * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * *
F 207 0.04: * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * *
G 212 0.04: * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * *
H 152 0.03: * * * * * * * * * * * * * * * * * * * * * * * * *
I 201 0.04: * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * *
J 210 0.04: * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * *
K 215 0.04: * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * *
*
L 219 0.04: * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * *
*
M 199 0.04: * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * *
N 218 0.04: * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * *
*
O 133 0.03: * * * * * * * * * * * * * * * * * * * * *
P 221 0.04: * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * *
* *
Q 204 0.04: * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * *
R 188 0.04: * * * * * * * * * * * * * * * * * * * * * * * * * * * * * *
S 192 0.04: * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * *
T 188 0.04: * * * * * * * * * * * * * * * * * * * * * * * * * * * * * *
U 211 0.04: * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * *
V 191 0.04: * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * *
W 206 0.04: * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * *
X 141 0.03: * * * * * * * * * * * * * * * * * * * * * * *
Y 160 0.03: * * * * * * * * * * * * * * * * * * * * * * * * * *
Z 211 0.04: * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * *
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