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M4 Project

This is the second break of the M4 Project:

Ciphertext (stripped of indicator groups):


tmkfnwzxffiiyxutihwmdhxifzeqvkdvmqswbqndyozftiwmjhxhyrpaczugrremvpanwxgtkthn
rlvhkzpgmnmvsecvckhoinplhhpvpxkmbhokccpdpevxvvhozzqbiyieouseznhjkwhydagtxdjd
jkjpkcsdsuztqcxjdvlpamgqkkshphvksvpcbuwzfizpfuup

Plaintext (as seen in the server logs):


Date: 2006-03-07 10:03:23
Score: 5211199
UKW: B
W/0: B241
Stecker: ATCLDHEPFGIOJNKQMURX
Rings: AANV
Message key: MCSF

vvvjschreederjaufgeleitkursfuenffuenfgradnichtsgefundenymarscaierebefohlenes
quadratxstanrortmarquantonjotadreineunneunfuenfxsssooovieryseedremyeinsnulyy
einsnulbedecktyzwoachtmbsteigtynbbelsichteinssmt

Confirmed result:

Dan Girard had already told me privately that this might be the plaintext for the third signal. That was two weeks ago. Well spotted, Dan! - Of course the message had to be broken first to be sure. The plaintext of the message appears in the war diary of U623, which can be found at NARA, Microfilm Publication T1022, Roll 3385.


0425        Ausgang FT. 0246/21/203:
                Auf Geleitkurs 55° nichts gefunden, marschie-
                re befohlenes Qu. Standort Marqu. AJ 3995.
                SO 4, See 3, 10/10 bedeckt, 28 mb steigend,
                Nebel, Sicht 1 sm.
                                       Schroeder

Translation:


0425        Outgoing Radio Signal 0246/21/203:
                 Found nothing on convoy's course 55°, [I am] moving to
                 the ordered [naval] square. Position naval square AJ 3995.
                 [wind] south-east [force] 4, sea [state] 3, 10/10 cloudy,
                 [barometer] [10]28 mb [tendency] rising, fog, visibility 1 nautical mile.
                                        Schroeder

Explanation:


0246/21/203:  time/date/message serial number

AJ 3995:      German naval grid reference, 56-33 N, 37-36 W

Schroeder     Hermann Schröder, Oberleutnant zur See on U623

Thanks to Dan Girard, Ralph Erskine and several people on the mailing list for providing the necessary information and corrections.


Contact:

Stefan Krah <website @ bytereef.org>