General Discussions
This is the place to discuss general issues related to the U-boat war or the war at sea in WWII.
Re: B-Dienst Successes - Admiralty Code Broken
Posted by:
glider1
()
Date: December 03, 2008 09:40PM
Funkmeister Wrote:
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>... The codes are relatively simple, and used on
> tactical levels. ...
> Ciphers are different. They are much more
> complicated, and for any cipher it need much more
> time, and knowledge, to break it.
But a good enciphered code can be very difficult to break. My recollection is that Bletchley Park could not break an important Italian naval enciphered code.
True, the B-Dienst solved the Anglo-American convoy code for the North Atlantic (Naval Cypher No 3 - an enciphered code, despite the name) from about Feb 1942 to 10 June 1943. But Naval Cypher No. 5 replaced it then for Anglo-American use, and neither Naval Cypher No. 5 nor any of its successors were broken by the B-Dienst during the remainder of the war. Instead, the B-Dienst had to rely on pickings from minor codes, such as 'Gallien' and other secondary systems such as Cofox or Loxo, although only Gallien provided intelligence against the Atlantic convoys, and that was mainly about stragglers.
> ... The best decision of the British was that their
> codebreakers cared also about their ciphers-
But Bletchley Park had no authority over the codes used by the Royal Navy - it could only advise. And Bletchley did not take enough interest in naval cipher security, which was mainly the province of NID 10 - hence the disasters with Naval Cypher No 3.
> ... And, it is not easy to introduce completely new
> system of codes and ciphers, especially in war.
Too true. That's the main reason why Naval Cypher No 3 remained in force for over 18 months - for far too long.
> the Kriegsmarine didn't change the
> Enigma machines, although they doubted in possible
> codebreaking. They added the fourth rotor, and
> it was all they could to do at the time.
Dönitz expressed doubts about Enigma's security on a number of occasions, but Stummel and the Kriegsmarine technical staff always took the view that it was secure, except against capture of the keys. Eventually, Lt Hans-Joachim Frowein was lent by department 4 SKL III (cryptanalysis) to 4 SKL II (radio, including cipher security) for six months in 1944. Although he and his ten staff had no experience of breaking machine ciphers, by December he had developed a method to solve M4, and advised on a method to improve it. But nothing seems to have been done to do so.
On those doubts and Frowein's work, see R Ratcliffe, 'Delusions of Intelligence' and 'Action this day' (2001 - Erskine & Smith, eds).
There were, of course, many Kriegsmarine Enigma ciphers. For some reason, Kriegsmarine cipher security was very poorly organised. The Kriegsmarine made it easy for Bletchley to break about five Enigma ciphers eg Porpoise (Süd; called Hermes after January 1944), due to a poor procedure that the Heer & Luftwaffe abandoned in May 1940. Porpoise did not drop it until June 1944!
RE
-------------------------------------------------------
>... The codes are relatively simple, and used on
> tactical levels. ...
> Ciphers are different. They are much more
> complicated, and for any cipher it need much more
> time, and knowledge, to break it.
But a good enciphered code can be very difficult to break. My recollection is that Bletchley Park could not break an important Italian naval enciphered code.
True, the B-Dienst solved the Anglo-American convoy code for the North Atlantic (Naval Cypher No 3 - an enciphered code, despite the name) from about Feb 1942 to 10 June 1943. But Naval Cypher No. 5 replaced it then for Anglo-American use, and neither Naval Cypher No. 5 nor any of its successors were broken by the B-Dienst during the remainder of the war. Instead, the B-Dienst had to rely on pickings from minor codes, such as 'Gallien' and other secondary systems such as Cofox or Loxo, although only Gallien provided intelligence against the Atlantic convoys, and that was mainly about stragglers.
> ... The best decision of the British was that their
> codebreakers cared also about their ciphers-
But Bletchley Park had no authority over the codes used by the Royal Navy - it could only advise. And Bletchley did not take enough interest in naval cipher security, which was mainly the province of NID 10 - hence the disasters with Naval Cypher No 3.
> ... And, it is not easy to introduce completely new
> system of codes and ciphers, especially in war.
Too true. That's the main reason why Naval Cypher No 3 remained in force for over 18 months - for far too long.
> the Kriegsmarine didn't change the
> Enigma machines, although they doubted in possible
> codebreaking. They added the fourth rotor, and
> it was all they could to do at the time.
Dönitz expressed doubts about Enigma's security on a number of occasions, but Stummel and the Kriegsmarine technical staff always took the view that it was secure, except against capture of the keys. Eventually, Lt Hans-Joachim Frowein was lent by department 4 SKL III (cryptanalysis) to 4 SKL II (radio, including cipher security) for six months in 1944. Although he and his ten staff had no experience of breaking machine ciphers, by December he had developed a method to solve M4, and advised on a method to improve it. But nothing seems to have been done to do so.
On those doubts and Frowein's work, see R Ratcliffe, 'Delusions of Intelligence' and 'Action this day' (2001 - Erskine & Smith, eds).
There were, of course, many Kriegsmarine Enigma ciphers. For some reason, Kriegsmarine cipher security was very poorly organised. The Kriegsmarine made it easy for Bletchley to break about five Enigma ciphers eg Porpoise (Süd; called Hermes after January 1944), due to a poor procedure that the Heer & Luftwaffe abandoned in May 1940. Porpoise did not drop it until June 1944!
RE
