GCHQ - Eastcote 31° 57′N, 35° 56′ E
1st february 1949.
Dear Mr Michael Cum,
We have just
intercepted a message from our French ally.
Can you try to dechiper it?
Hint: before sending
the first message of the day, the French
telegraphers (ALBERT and PIERRE) chat after adjusting the
key. They reset the message key after each sentence. We know a
few problable words: MESSAGE, RECOI, ENVOI.
From another message
we have deduced the Inner setting:
"II,IV,III,9,3,5,7,I,V,1"
Hug Alexander, H section chief,
NYDQ3WDKQV8I8JJBY+DJE33NKKZ+DRKIZT+ZP
O+LWEG+BBLFEU+JHCQSHPCPAKK4++D3O3JUHC/TQVSJIXPDQX
NYEEPVEQ4SDEEGJZ999WUSJVHRK8T33RCH/X
NZZQCRBQP4/T3WXZAOOWUM/WYZUXYWFN8R9QLLFGH
+CLAHER3QDDDQN/3AEDJY4RGJZUX4ZXJZTLHBMQIRXICAZHX
O+LATFMS8T/KC3DHIWAJR33NEUD8QD3Y/KXMVYA8V+WWWNZZFD
OONXJ/RSI8ECMCQVTDNZ9T8RT9RSVPRJYPBSVQ4F8+HHTPZBBJ
ZI3JPKMXAOPJE9YYYL8C4UAGPWB9CKGJUTDARD/CGYQ34B4UW/
9YUFWEALECKZFXKMU+DS8+F8KB3JYFHRQIGCTBLFRN/LSINK3+
RH+SWAKTJXHJGQYZLO8L4GCCFA+VLDY8WA+XP+KFE4YYK3XMJK
MTD8ZKFPBVFLOWDH3CIAEMPYLYHZRUAAW3TSG+BHCKXZSXGKUW
4XZGWSLHGHVCZDYD9IHACQADKPQ84F8TD8C+CSAWCFTBDYJ4S