General Discussions
This is the place to discuss general issues related to the U-boat war or the war at sea in WWII.
Cipher penetrations
Posted by:
SuperKraut
()
Date: May 19, 2001 07:28AM
<HTML>First some definitions. A cipher system changes the letters of a language according to a predetermined pattern. A code takes the words of the text and substitutes other words or numbers for them.
Cipher systems are solved by trial and error (analysis) and one knows the solution is found when one gets a readable text. Paper systems used relatively short patterns and can be solved by using this periodicity. Solving codes by analysis takes a lot of text because the meaning of the various code words/numbers must be validated in different texts. However, codes are notoriously vulnerable to theft and treason.
The invention of cipher machines led to very long ciphers which required machines to analyze. The main weakness of many machine ciphers is still periodicity in the cipher, which is how both Purple and Fish were cracked by analysis. Enigma also generated some periodicities, but they were not used at the time due to inadequate computing power. Today\'s parallel processing super computers can crack a rotor machine in a matter of minutes. In theory, any periodicity can be used to solve a cipher, it is just a question of time and computing power.
\">During WWII virtually everyone was using a variation of the same rotor machine. ….. But in fact, most of the codes were penetrated, at least at one time or another: US and British codes were penetrated by B-Dienst, and of course the German and Japanese codes were badly compromised.<\" The two sentences do not go together. The only rotor system which was penetrated in WWII was Enigma. The Japanese Purple machine was not a rotor device. The early Allied codes and ciphers which were penetrated by the Germans were paper based systems or used the simple Jefferson wheel.
In principle, there are three ways to crack a cipher or code, analysis, theft and treason. The system can only be designed and operated to foil the first two. There is no bulletproof defense against treason. All paper cipher systems were eventually cracked by analysis, however many codes were not due to insufficient text length. Enigma was cracked because it was not operated to foil theft. The American post war rotor systems were cracked by treason.
The bottom line is that no code or cipher system is 100% safe because there is always the possibility of treason, however, this applies to all secrets and one has to live with it. On the other hand, using and operating a system which can be cracked over a long time period by analysis and/or theft is simply incompetence. Defending against the combination of theft and analysis is difficult. It is almost impossible to prevent a penetration over a limited time period once theft occurs, but the well designed system attempts to reduce that time period to insignificance.
The apparent German failure with Enigma was assuming it was safe from analysis even if the machine and rotors were stolen. I say apparently because it is not known if the assumption was made that a machine would never fall into the hands of the enemy. As you say, it is a pretty naïve assumption. On the other hand, all bets are off in the case of Enigma because it may well have been compromised by one sided treason, or as I like to call it, \"creative incompetence\".
Regards,
SuperKraut
</HTML>
Cipher systems are solved by trial and error (analysis) and one knows the solution is found when one gets a readable text. Paper systems used relatively short patterns and can be solved by using this periodicity. Solving codes by analysis takes a lot of text because the meaning of the various code words/numbers must be validated in different texts. However, codes are notoriously vulnerable to theft and treason.
The invention of cipher machines led to very long ciphers which required machines to analyze. The main weakness of many machine ciphers is still periodicity in the cipher, which is how both Purple and Fish were cracked by analysis. Enigma also generated some periodicities, but they were not used at the time due to inadequate computing power. Today\'s parallel processing super computers can crack a rotor machine in a matter of minutes. In theory, any periodicity can be used to solve a cipher, it is just a question of time and computing power.
\">During WWII virtually everyone was using a variation of the same rotor machine. ….. But in fact, most of the codes were penetrated, at least at one time or another: US and British codes were penetrated by B-Dienst, and of course the German and Japanese codes were badly compromised.<\" The two sentences do not go together. The only rotor system which was penetrated in WWII was Enigma. The Japanese Purple machine was not a rotor device. The early Allied codes and ciphers which were penetrated by the Germans were paper based systems or used the simple Jefferson wheel.
In principle, there are three ways to crack a cipher or code, analysis, theft and treason. The system can only be designed and operated to foil the first two. There is no bulletproof defense against treason. All paper cipher systems were eventually cracked by analysis, however many codes were not due to insufficient text length. Enigma was cracked because it was not operated to foil theft. The American post war rotor systems were cracked by treason.
The bottom line is that no code or cipher system is 100% safe because there is always the possibility of treason, however, this applies to all secrets and one has to live with it. On the other hand, using and operating a system which can be cracked over a long time period by analysis and/or theft is simply incompetence. Defending against the combination of theft and analysis is difficult. It is almost impossible to prevent a penetration over a limited time period once theft occurs, but the well designed system attempts to reduce that time period to insignificance.
The apparent German failure with Enigma was assuming it was safe from analysis even if the machine and rotors were stolen. I say apparently because it is not known if the assumption was made that a machine would never fall into the hands of the enemy. As you say, it is a pretty naïve assumption. On the other hand, all bets are off in the case of Enigma because it may well have been compromised by one sided treason, or as I like to call it, \"creative incompetence\".
Regards,
SuperKraut
</HTML>
| Subject | Written By | Posted |
|---|---|---|
Bletchley Park or just lucky???
|
William Engel | 05/15/2001 12:46PM |
|
RE: Bletchley Park or just lucky???
|
Marc Haldimann | 05/15/2001 01:47PM |
|
RE: Bletchley Park or just lucky???
|
MPC | 05/15/2001 07:06PM |
|
RE: Bletchley Park or just lucky???
|
William Engel | 05/16/2001 05:21AM |
|
Enigma
|
SuperKraut | 05/16/2001 08:44AM |
|
RE: Enigma
|
William Engel | 05/16/2001 09:27AM |
|
Alternative explanation
|
SuperKraut | 05/16/2001 03:06PM |
|
Alternative explanation
|
SuperKraut | 05/16/2001 03:07PM |
|
RE: Alternative explanation
|
William Engel | 05/17/2001 05:46AM |
|
Poor coordination
|
SuperKraut | 05/17/2001 08:07AM |
|
Enigma and faith
|
kurt | 05/17/2001 04:21PM |
|
Cipher penetrations
|
SuperKraut | 05/19/2001 07:28AM |
|
Congratulations to you both...
|
MPC | 05/16/2001 03:49PM |
|
RE: Bletchley Park or just lucky???
|
Rainer Bruns | 05/16/2001 06:25PM |
|
RE: Bletchley Park or just lucky???
|
Kris | 05/16/2001 05:14PM |