Tirpitz on the loose

[Dave Saxton]

What Hitler did not know and Raedar refused to believe possible,was that the British had developed a top secret computer capable of cracking the Schlissel-M-the machine ciphers used by the German Navy-KM-rapidity had varied from day to day but had been crippling for the Germans.These decoded messages stamped with the special Ultra secret classification had led the British Battle Fleet to the Bismarck in May 1941-it was this device that tipped off the Admiralty that Tirpitz had arrived in Norway along with the rest of the entourage PE,AS plus destroyers.It was Ultra that enabled the Admiralty to station a submarine in Trondheim approaches

Where did you get this from? It does not correlate well with research I have done on this topic. Some of it is in part correct, but only in part. In addition it is greatly over simplified.

[aurora]

Not being an Ultra buff-All of the above came verbatim from David Irving's book "The Destruction of Convoy PQ17"-I have found bits and pieces in John Winton's "ULTRA AT SEA" However the internet came up with a full dissertation which might interest you- see link below :-

http://www.dtic.mil/get-tr-doc/pdf?AD=A ... tTRDoc.pdf

[aurora]

Winton's ULTRA AT SEA does indicate that Ultra decrypts were continuous throughout the PQ17 incident and David Irving's book is shown in full-see link
Would you be so kind as to explain to me "what was over simplified"and what I could have done to expand on the subject in question.

http://www.fpp.co.uk/books/PQ17/1968edition.pdf

[Dave Saxton]

Would you be so kind as to explain to me "what was over simplified"and what I could have done to expand on the subject in question.

http://www.fpp.co.uk/books/PQ17/1968edition.pdf

viewtopic.php?f=9&t=6540

What Hitler did not know and Raedar refused to believe possible,was that the British had developed a top secret computer capable of cracking the Schlissel-M-the machine ciphers used by the German Navy-KM

This is both correct and misleading. Indeed computers were developed and they worked great on the Luftwaffe Enigma beginning in June 1940, but they didn't work reliably on the naval Enigma, at least not prior to 1943. If they did work then there would have been no need to steal the keys from the weather ships during 1941. Once in awhile (months apart) they did manage to decipher some aspecs of naval Enigma but that was the exception not the rule. Engima was not something that once "broken" the job was done. It had to be rebroken every single day.The stolen keys they had which allowed deciphers to occur from late May 1941 expired at the end of Sept 1941. Then it was back to hit and miss with long delays again.

the special Ultra secret classification had led the British Battle Fleet to the Bismarck in May 1941-

This is not correct. It was traditional Reccon and Intel ranging from Swedish coast watchers, to Recon flights, and cruiser patrols and more. This is of course well known here at this site. At that time Bletchley Park was just beginning to be able to de-cipher some naval Enigma due to the keys stolen in the first weather ship raids and the unexpected capture of U-110, but with delays of at least 4 days and more likey two weeks time. Any Intel gained from naval Enigma during the Bismarck operation was stale and came after Bismarck sunk. There was a deciphering of some Lufwaffe Enigma messages that indicated that Bismarck was making for France.

this device that tipped off the Admiralty that Tirpitz had arrived in Norway

This was possible because TP transfered to Norway in Jan 1942 and the fourth rotor Engima began operations on Feb 1st 1942.

The new naval Enigma locked the British out until Dec 1942. PQ17 was during July 1942, so it's not possible that Ultra was able to de-cipher German Naval Enigma transmissions during PQ17. However, not all Ultra Intel was from de-ciphering of Engima. Traffic analysis, the breaking of other codes, and being able to read non naval enigma messages could all have contributed. For Example, Ultra sent a warning to the Admilty about Scharnhorst and Gneisenau being able to fall upon the Glorious in June 1940. They absolutely could not de-cipher naval Engima at that time, but their warning was based upon traffic analysis and D/Fing. The call signs of major warships were known of course. Nonetheless, this is normal radio Intel that anybody was capable of. It wasn't special at all during PQ17.

Indeed, I'm afraid the Germans had the edge in radio Intel at the time of PQ17. The German Navy's radio Intel service B-Dienst had broken the RN and Merchant Marine codes from 1935 and in 1942 they were at the height of their powers. The German admirals were able read RN messages before British admirals could until about Feb 1944.

[aurora]

Many thanks Dave for your patience and forbearance-the information in David Irving's book was null and void but- who was I to know that?? I have little knowledge of Codes and Codebreaking; but I gather from you that where the word Ultra is used-it may have come via another source ie Luftwaffe or Uboat Command; but not KM Command and Code breaking was an ongoing operation-never truly finished!!!;but I guess that I am, having nothing further to say.

PS Do you have John Winton's ULTRA AT SEA-if so what do you think of it???? Is there something better???

[Dave Saxton]

Many thanks Dave for your patience and forbearance-the information in David Irving's book was null and void but- who was I to know that?? I have little knowledge of Codes and Codebreaking; but I gather from you that where the word Ultra is used-it may have come via another source ie Luftwaffe or Uboat Command; but not KM Command and Code breaking was an ongoing operation-never truly finished!!!;but I guess that I am, having nothing further to say.

The interesting thing about Irving's information is that it was from a 1968 publication and Ultra wasn't made public before 1974. Irving was privy to some, but incomplete, classified information and in violation (perhaps unwittingly) the Official Secrets Act. His information is part correct but due to the incompleteness of his information at the time rather misleading.

It's true that radio Intel came from a wide variety of sources but it was all filtered through Ultra.
For the most part when we think of Ultra it is Engima deciphering and that was indeed a war winning achievement by the Allies, especially post 1942.

[aurora]

Quote
"The interesting thing about Irving's information is that it was from a 1968 publication and Ultra wasn't made public before 1974. Irving was privy to some, but incomplete, classified information and in violation (perhaps unwittingly) the Official Secrets Act. His information is part correct but due to the incompleteness of his information at the time rather misleading".

The above says it all really Dave; but how easily the reader is sucked into a "mish mash" of fact and fiction.I did ask you if you could recommend some reputable reading on this particular topic of Ultra/Enigma

[tommy303]

It's true that radio Intel came from a wide variety of sources but it was all filtered through Ultra.
For the most part when we think of Ultra it is Engima deciphering and that was indeed a war winning achievement by the Allies, especially post 1942.

An interesting example of this comes from the pursuit of the Bismarck. As mentioned in another thread, messages too and from Bismarck could not be immediately deciphered and were therefore of little tactical use--if I recall it might take days or even weeks to eventually decode a message. When Luetjens gave the RN the slip, search patterns were hampered by a lack of knowledge of his intentions. However, one of the intelligence people at Bletchley Park noticed that around noon on May 24, 1941 command level messages being sent to Bismarck ceased coming from Wilhelmshaven and instead were coming from a command center located in France. He properly deduced that Bismarck had come under control of Group West and was in all probability heading to France.

[aurora]

Thanks Thomas-Never mind the signals which took ages to decipher-a smart intel man with a sharp power of reasoning will find a solution.It is a fascinating subject though.

[Dave Saxton]

I did ask you if you could recommend some reputable reading on this particular topic of Ultra/Enigma

You could do no better than "Seizing the Enigma" by David Kahn.

[Dave Saxton]

It's true that radio Intel came from a wide variety of sources but it was all filtered through Ultra.
For the most part when we think of Ultra it is Engima deciphering and that was indeed a war winning achievement by the Allies, especially post 1942.

An interesting example of this comes from the pursuit of the Bismarck. As mentioned in another thread, messages too and from Bismarck could not be immediately deciphered and were therefore of little tactical use--if I recall it might take days or even weeks to eventually decode a message. When Luetjens gave the RN the slip, search patterns were hampered by a lack of knowledge of his intentions. However, one of the intelligence people at Bletchley Park noticed that around noon on May 24, 1941 command level messages being sent to Bismarck ceased coming from Wilhelmshaven and instead were coming from a command center located in France. He properly deduced that Bismarck had come under control of Group West and was in all probability heading to France.

This is a classic example of traffic analysis.

A book I'm just rediscovering is: "And I was There". It's about the code breakers at Pearl Harbor and that effort. Traffic analysis was a major factor in the American effort in the Pacific as well as de-ciphering the Japanese codes and ciphers.

[aurora]

Dave- many thanks--What about WITHOUT ENIGMA by Kenneth Macksey????

[tommy303]

In addition to Enigma, there were other German machines and codes in use, some of which were also broken and some which were not or only partly so. The Lorenz SZ-40/42 was a cypher machine for teleprinter and was famously broken by the Swedes as high level communications between Norway and Germany were encrypted and sent via land lines which passed through Sweden and could thus be tapped; some radio transmissions were sent using this machine and Bletchley Park assigned the code name TUNNY to these. It was possible, after much effort to break the code, but only if the messages intercepted were long enough. Siemens also had a series of similar teleprinter cypher machines which were used at various times by high level commands for radio and land line communications. The T-52 Geheimschreiber was one such, and its cypher, known as Sturgeon, could be intercepted and eventually broken only by Bletchley if long messages were sent via radio transmission instead of land lines; on the whole, it was difficult and usually the messages tended to be of little value. Thus, both British and Swedish code breakers were only able to read a part of the traffic sent on this machine.

Another Siemens machine, the T-43 was a sophisticated machine whose code was named Thrasher by the British. It was one-time mixer type machine, and possibly the first of its kind, and to my knowlege, its code was not broken during the war.

[Dave Saxton]

In addition to Enigma, there were other German machines and codes in use, some of which were also broken and some which were not or only partly so. The Lorenz SZ-40/42 was a cypher machine for teleprinter and was famously broken by the Swedes as high level communications between Norway and Germany were encrypted and sent via land lines which passed through Sweden and could thus be tapped; some radio transmissions were sent using this machine and Bletchley Park assigned the code name TUNNY to these. It was possible, after much effort to break the code, but only if the messages intercepted were long enough. Siemens also had a series of similar teleprinter cypher machines which were used at various times by high level commands for radio and land line communications. The T-52 Geheimschreiber was one such, and its cypher, known as Sturgeon, could be intercepted and eventually broken only by Bletchley if long messages were sent via radio transmission instead of land lines; on the whole, it was difficult and usually the messages tended to be of little value. Thus, both British and Swedish code breakers were only able to read a part of the traffic sent on this machine.

Another Siemens machine, the T-43 was a sophisticated machine whose code was named Thrasher by the British. It was one-time mixer type machine, and possibly the first of its kind, and to my knowlege, its code was not broken during the war.

In addition some Enigma key nets were not "broken". This was mainly, as I understand it, because the traffic on these key nets were too sparse to give the computors much material to work on. I have been informed that one of these Enigmas never broken was the surface ship Enigma that would have been used by Tirpitz. Had the war continued, the Germans would have made Enigma more difficult to "crack" by the use of a variable wired reflector disk.

The USN also used rotor based cipher machines, but they used more rotors than Enigma and from about 1935 they were mostly superseded by "strip ciphers". These Strip machines used punch cards or Strips to set the substitutions of the machine for each message. Sort of a "bar code" type of key to use a modern analogy. The USN had reasoned rotor machines could eventually be "solved" by another machine running continuously, given enough time.

The IJN cipher machines did not use rotors but telephone type relays to scramble the permutations. The USN built special decoding machines at the Philadelphia Navy Yards that ran conituously breaking down IJN ciphers.