# Clock (cryptography)

﻿
Clock (cryptography)

In cryptography, the clock was a method devised by Polish mathematician-cryptologist Jerzy Różycki, at the Polish General Staff's Cipher Bureau, to facilitate decrypting German Enigma ciphers.

## Method

This method sometimes made it possible to determine which of the Enigma machine's rotors was at the far right, that is, in the position where the rotor always revolved at every depression of a key.[1]

Różycki's "clock" method was later elaborated by the British cryptologist Alan Turing at Bletchley Park in the development of a cryptological technique called "Banburismus."[2]

## Notes

1. ^ Rejewski 1984, p. 290
2. ^ Good 1993, p. 155

## 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, Frederick, Maryland: University Publications of America, ISBN 978-0890935477  A revised and augmented translation of W kręgu enigmy, Warsaw, Książka i Wiedza, 1979, supplemented with appendices by Marian Rejewski
• Rejewski, Marian (1984), "The Mathematical Solution of the Enigma Cipher: Appendix E"  of Kozaczuk 1984, pp. 272–91
• Good, Jack (1993), "Enigma and Fish", in Hinsley, F.H.; Stripp, Alan, Codebreakers: The inside story of Bletchley Park, Oxford: Oxford University Press, pp. 149–66, ISBN 978-0-19-280132-6

Wikimedia Foundation. 2010.

### Look at other dictionaries:

• Clock drift — refers to several related phenomena where a clock does not run at the exact right speed compared to another clock. That is, after some time the clock drifts apart from the other clock. This phenomenon is also used for instance in computers to… …   Wikipedia

• Transient-key cryptography — is a form of public key cryptography wherein keypairs are generated and assigned to brief intervals of time instead of to individuals or organizations. In a transient key system, private keys are used briefly and then destroyed, which is why it… …   Wikipedia

• List of World War II topics (C) — # C 108 Flying Fortress # C 46 Commando # C 47 Skytrain # C 54 Skymaster # C 76 Caravan # C 87 Liberator Express # C 14 class missile boat # C Force # C. Douglas Dillon # C. Dupre # C. Farris Bryant # C. J. Bolin # C. P. Stacey # C. R. Boxer # C …   Wikipedia

• Hardware random number generator — This SSL Accelerator computer card uses a hardware random number generator to generate cryptographic keys to encrypt data sent over computer networks. In computing, a hardware random number generator is an apparatus that generates random numbers… …   Wikipedia

• Enigma machine — Military Enigma machine …   Wikipedia

• VEST — High Level Structure of VEST General Designers Sean O Neil First published June 13, 2005 Cipher deta …   Wikipedia

• Criticism of Microsoft Windows — Contents 1 Criticisms that apply to several or all versions of Windows 1.1 Clock management 1.2 Hiding of filen …   Wikipedia

• Stream cipher — The operation of the keystream generator in A5/1, a LFSR based stream cipher used to encrypt mobile phone conversations. In cryptography, a stream cipher is a symmetric key cipher where plaintext digits are combined with a pseudorandom cipher… …   Wikipedia

• Biuro Szyfrów — The Biuro Szyfrów ([ˈbʲurɔ ˈʂɨfruf] ( listen), Polish for Cipher Bureau ) was the interwar Polish General Staff s agency charged with both cryptography (the use of ciphers and codes) and cryptology (the study of ciphers and codes,… …   Wikipedia