Patent GB-221796-A (GB)
Title: Improved apparatus for deciphering cipher messages
IPC: G09C1/12
Filed: 1924-09-05
Abstract: 221,796. Aktiebolaget Cryptograph. Sept. 10, 1923, [Convention date]. Strip-controlled type-wheel machines for decoding.-The cryptographic apparatus described in Specifications 152,625 and 197,763 is combined with the telegraphic printing-apparatus described in Specification 164,370. The typewheel of the printing-apparatus is now arranged so that the stop-bar b is out of the path of the selectorbars V<10> controlled by the perforated tape, and the selector-bars are adapted to close contacts k<10>t in circuit with magnets Mt having armatures 44 co-operating with the stop-bar. The motor E of the printing-apparatus is started by adjusting a switch Q to close contacts Q<1>, Q<2>, and when the perforated tape is fed through the printing-mechanism, the signals cause the selector-bars to close their contacts, the associated magnets thereupon causing their armatures to arrest the typewheel in position for printing the selected characters. A rotary commutator ap prevents sparking at the contacts k<10>t. The ciphering-cylinders C<1>, C<2> and the keydiscs N<1> - - N<4> are set initially in the positions communicated by the telegram, and the reversing- switch W is set for printing in clear text. The first series of signals, representing the address &c. in clear text, cause the contacts k<10>t operated by the selectorbars, to close (1) the circuits of the magnets Mt, (2) circuits passing through solenoids S<4>, S<5>, and one or more of a set of contacts k<5> - - k<8>, and f<1> - - f<4>, controlled bv the key-discs N<1> - - N<4>, and a secondary key V<5> respectively, and (3) circuits passing through solenoids S<3>1 - - S<3>4. The three circuits are effected to arrest the type-wheel, to turn one or both of the ciphering-cylinders, and to turn the key-discs respectively. The spacing selectorbar V<10>m closes a contact k<10>m in circuit with a magnet Mm having an armature 44m. The first series of signals is followed by a shift signal controlling a selector-bar V<10>x which closes the circuit of a magnet Sw, operating, by a device Lk, the reversing-switch W, the apparatus being thereby set for de-ciphering. The next series of signals, representing the ciphered message, cause the contacts K<10>t operated by the selector-bars to close circuits passing through the ciphering- cylinders C<1>, C<2> and the magnets Mt to effect printing in clear text, and also to close the abovedescribed circuits for turning the ciphering-cylinders and the key-discs. The ciphered message is divided into groups of five signals, and, to prevent erroneous translation if a group accidentally contains less or more than five signals, there are provided commutators a<1>, a<2> which are driven at one-sixth the speed of the main driving-shaft, and are provided with conducting-sections occupying one-sixth and five-sixths of the circumference respectively. Contacts k<10>m, k<10>c operated by the selector-bar V<10>m, close and open circuits through the commutators a<1>, a<2> respectively, at the moment a space between a group of signals is in position. The commutator a<2> is arranged, when a space between groups of signals is in position, to break the circuits that turn the ciphering-cylinders and key-discs. If a group contains less than five signals, the seletor-arm V<10>m establishes a circuit through the commutator a<1> and a magnet Mk, a contact k, p being thereby opened and the motor F arrested. The switch Q is then adjusted, to the position indicated in dotted lines, for manual deciphering and the keyboard is employed to advance the tape until the next group of signals is in position. If a group contains more than five signals, the commutator a<1> closes the circuit of the magnet Mk when the sixth signal is in position, and the motor E is arrested. The tape is then adjusted manually, and the apparatus is re-started. The commutator a<1> is provided with a rotary index, and a dial graduated 0 - - 5, for indicating the number of signals in an erroneous group. The ciphered message is followed by a shift signal which adjusts the reversing-switch W for printing in clear text the final part of the message containing a statement of the number of cipher groups. If the printing-apparatus is out of order the message can be deciphered manually by reading the message and operating the keys of the cryptographic apparatus, the switch Q being adjusted to cut out the circuits of the printing-apparatus. Letter-spacing mechanism.- To prevent feeding of the printed tape when a space between groups of signals is in position, a magnet Mh for holding the feed-pawl x in engagement with the ratchet-wheel is in a circuit which is broken by the commutator a<1> when the space between a group of signals is in position. A spring Z thereupon releases the pawl and arrests the feed.