Grill (cryptology)

Biuro Szyfrów

Methods and technology
"ANX" · Enigma "doubles" · Grill Clock · Cyclometer · Card catalog Cryptologic bomb Zygalski sheets · Lacida
Locations
Saxon Palace · Kabaty Woods PC Bruno · Cadix
Personnel
Chief Gwido Langer Deputy Chief Chief of Radio Intelligence Chief of German Section Maksymilian Ciężki German Section cryptologists Marian Rejewski · Jerzy Różycki Henryk Zygalski · Antoni Palluth Wiktor Michałowski Chief of Russian Section Jan Graliński Russian Section cryptologist Piotr Smoleński Others Jan Kowalewski Stanisław Leśniewski Stefan Mazurkiewicz Franciszek Pokorny Wacław Sierpiński

The Enigma cipher machine
Enigma machine Enigma rotors Breaking Enigma Polish Cipher Bureau Doubles Grill Clock Cyclometer Bomba Zygalski sheets Bletchley Park Banburismus Herivel tip Crib Bombe Hut 6 Hut 8 PC Bruno Ultra

The grill (Polish: ruszt), in cryptology, was a method used chiefly early on, before the advent of the cyclometer, by the mathematician-cryptologists of the Polish Cipher Bureau in decrypting German Enigma-machine ciphers.

Method

The grill method is described by Marian Rejewski as being "manual and tedious" and, like the later cryptologic bomb, as being "based... on the fact that the plug connections [in the Enigma's commutator, or "plugboard"] did not change all the letters." Unlike the bomb, however, "the grill method required unchanged pairs of letters [rather than] only unchanged letters."

The grill method found application as late as December 1938 in working out the wiring in two Enigma rotors newly introduced by the Germans. (This was made possible by the fact that a Sicherheitsdienst net, while it had introduced the new drums IV and V, continued using the old system for enciphering the individual message keys.)

References

• Kozaczuk, Władysław (1984), Enigma: How the German Machine Cipher was Broken, and how it was Read by the Allies in World War Two, edited and translated by Christopher Kasparek [a revised and augmented translation of W kręgu enigmy, Warsaw, Książka i Wiedza, 1979, supplemented with appendices by Marian Rejewski], Frederick, MD, University Publications of America, ISBN 0-89093-547-5 
• Rejewski, Marian (1984c), Summary of Our Methods for Reconstructing ENIGMA and Reconstructing Daily Keys, and of German Efforts to Frustrate Those Methods: Appendix C  of Kozaczuk 1984, pp. 241–45
• Rejewski, Marian (1984d), How the Polish Mathematicians Broke Enigma: Appendix D  of Kozaczuk 1984, pp. 246–71
• Rejewski, Marian (1984e), The Mathematical Solution of the Enigma Cipher: Appendix E  of Kozaczuk 1984, pp. 272–291