Chapter 5: Analysis of a four-wheel Hagelin cipher machine

---Solution

The plain text:

  ALLIED ADVANCES IN NEW GUINEA AND THE SOLOMONS STOP BY 
  LATE ONE NINE FOUR TWO COMMA JAPANESE HEADQUARTERS 
  DECIDED TO MAKE GUADALCANAL THEIR PRIORITY DOT THEY 
  ORDERED THE JAPANESE ON THE KOKODA TRACK COMMA WITHIN 
  SIGHT OF THE LIGHTS OF PORT MORESBY COMMA TO RETREAT 
  TO THE NORTHEASTERN COAST OF NEW GUINEA DOT AUSTRALIAN 
  AND U DOT S DOT ATTACKED THEIR FORTIFIED POSITIONS AND 
  AFTER MORE THAN TWO MONTHS OF FIGHTING IN THE BUNA DASH 
  GONA AREA FINALLY CAPTURED THE KEY JAPANESE BEACHHEAD 
  IN EARLY ONE NINE FOUR THREE STOP IN JUNE ONE NINE FOUR 
  THREE COMMA THE ALLIES LAUNCHED OPERATION CARTWHEEL 
  COMMA WHICH DEFINED THEIR OFFENSIVE STRATEGY IN THE 
  SOUTH PACIFIC DOT THE OPERATION WAS AIMED AT ISOLATING 
  THE MAJOR JAPANESE FORWARD BASE AT RABAUL AND CUTTING 
  ITS SUPPLY AND COMMUNICATION LINES DOT THIS PREPARED 
  THE WAY FOR NIMIT S ISLAND DASH HOPPING CAMPAIGN 
  TOWARDS JAPAN STOP 

Inner key:
  ABC____H_JK___OPQ__TU__
  __CDE_G__JK__N_PQ__T_
  _BC_____I_K_M__P_R_
  _BC_EFG__J__MN_PQ
  11:1:4:9, 2 overlaps: (4-5), (5-6)


External key: LLKJIH