Doenitz's "Arctic Wolves" used radio intercepts of communications from the Soviet fleet to work in the Arctic. Fascist submarines were in the Barents, White and Kara Seas, as well as in the mouth of the Yenisei, in the Ob Bay, the Laptev Sea and off the coast of Taimyr. The main target, of course, was the civilian ships of the convoys of the Northern Sea Route. In the period preceding the Great War, the Germans listened to our radio broadcast from the Norwegian city of Kirkenes. But already in 1942, on the island of Alexandra Land, which is part of the Franz Josef Land archipelago, the 24th base of the meteorological and direction finding service of the Kriegsmarine was built. Submariners of the Third Reich often stopped at this point to replenish supplies and rest. The 24th base was not the only one - over time, a whole network of direction finders was deployed in the Arctic, which additionally performed the function of coordinators of the actions of the submarine forces.
The communication between the fascist submarines in the waters of the Arctic was built in a rather nontrivial way. So, in the summer of 1943, the acousticians of the Soviet minesweeper recorded in the area of Cape Zhelaniya (Novaya Zemlya archipelago) a real acoustic communication line between enemy submarines. According to experts, the Germans exchanged four-digit sound-like texts, and this was recorded on four submarines at once. Obviously, the submariners simply tapped with steel objects, using the hull as a giant drum. In the second half of the war, the Germans were already able to communicate by radio with each other at depths not exceeding 20 meters. And the light signaling was used on the surface.
Kriegsmarine submarines have often fallen victim to the war on the cryptographic front
If the civilian fleet of England used frankly outdated ciphers until the middle of the war, then the Soviet one often did not have them at all. The merchant fleet of the Main Directorate of the Northern Sea Route conducted negotiations on air in plain text! Such messages dealt with the whereabouts of ships, convoy routes and winter quarters for polar explorers. Only serious losses from German torpedoes forced the suicide practice to end in 1943. The Nazis also received information about Soviet codes through forceful actions - in September 1944, a German landing party landed from a submarine at Cape Sterligov and captured the radio codes of the polar station.
Karl Doenitz sees off another "wolf" from the "pack" to the sea
Soviet radio intelligence also did not sit idly by and worked quite actively in the Arctic. Specially organized coastal groups, naval vessels and civil polar stations worked to intercept enemy radio communications. The reconnaissance of the Northern Fleet carefully analyzed all incoming information, which made it possible to identify the places of accumulation of German submarines. Due to this, the convoys bypassed such "rat nests" at a safe distance. If it was not possible to bypass such a congestion, then escort escort of ships was intensified. The work of the interception services and analysts of the Northern Fleet allowed, in the end, to reduce the losses of civilian ships from the actions of German submariners. Often, German submarine forces suffered losses from collisions with the Soviet fleet. August 1943 was marked by the victory of the S-101 submarine (commander - Lieutenant Commander E. N. Trofimov, senior on board - Captain 2nd Rank P. I. Egorov) over the fascist submarine U-639 (commander - Chief Lieutenant Walter Wichmann). Knowing from the reports on the German radio exchange about the submarine search square, the C-101 sent three torpedoes to the bottom of the U-639, which was calmly surfacing. The Nazis went after a dirty business - planting mines in the Ob Bay. At the site of the sinking of the German boat and 47 submariners, they found an almost intact signal book, which later became the "golden key" of Soviet decoders.
Grand Admiral Karl Doenitz with his staff
Now back to Enigma. More precisely, to the doubts of the Germans about the resistance of this encryption machine to hacking. It was the active interception of British radio communications that created a false impression among the leadership of the German army and navy about the "strength" of its encryption algorithms. The British program "Ultra" with its seemingly absurd degree of secrecy fully justified itself and became a real triumph of the British intelligence services in this matter. Not once did the Germans in their radio intercepts smell even a hint of evidence of the Enigma break-in. Although back in 1930, one of the most professional German cryptanalysts Georg Schroeder, having met the miracle cipher, exclaimed: "Enigma is shit!" In fact, the main incentive for the further improvement of the "Enigma" to the Germans was minor incidents with the discrediting of ciphers and the principle of "it should be done". The most important panic officer in the Third Reich was Grand Admiral Doenitz, who constantly expressed his doubts about the endurance of the Enigma. He raised the alarm for the first time in mid-1940, when the C-26 meteorological survey vessel with a copy of the encryption machine on board disappeared. In the same year, the submarine U-13 went to the bottom, which also contained code books and Enigmas. But the Grand Admiral was then reassured by telling a beautiful story about washable ink on secret documents and strict instructions regarding the destruction of the cipher machine in case of flooding. This time Doenitz managed to lull his vigilance. The communications service of the Nazi German Navy carefully analyzed the cryptographic strength of the Enigma and was delighted with its own conclusions. Captain Ludwig Stammel, who is involved in analytical work, once said in this regard: "The cryptographic algorithms of the Enigma are much better than any other method, including the one used by the enemy." The blind belief of the leadership of the Wehrmacht and the Navy in the fact that the fascist ciphers remain unrevealed, while they themselves freely read British codes, seem strange. The feeling of superiority over the enemy and his intellectual abilities played a cruel joke with the Third Reich.
Karl Doenitz is the main critic of Enigma's cryptographic strength
But Doenitz did not stop. In the spring of 1941, he drew attention to how diligently the British fleet avoided the traps of the Kriegsmarine: the captains of the ships seemed to know in advance about the clusters of submarines. Karl was pacified this time too. Around the same period, the Germans hacked the English Navy code # 3. There was not a word in the radio intercepts that the enemy was reading Enigma. Despite this, certain precautions were nevertheless taken: the key installations of the encryption technology on ships and submarines have been separated since 1941. Also, the Grand Admiral significantly narrowed the circle of persons from the high command who had access to the coordinates of clusters of "wolf packs".
In his memoirs, Doenitz wrote:
“Whether the enemy read our radio traffic, and if so, to what extent, we failed to establish confidently, despite all our efforts. In many cases, the abrupt change in the course of the convoy led us to believe that the enemy was doing this. At the same time, there were many such cases when, in spite of the lively radio exchange of submarines in a certain area, adversary ships alone and even convoys went directly to that area,where ships have just been sunk or even a battle with submarines attacking the convoy has taken place.
If the above can be attributed to the obvious successes of the British operation "Ultra", then the failures of this super-secret program were also not taken seriously by the Germans. So, in May 1941, in Crete, the fascists got hold of a telegram for the British General Freiber, which contains information received by the British from the Enigma decryptions. Of course, this telegram was not communicated in direct text, but information of this level of secrecy was broadcast by the Germans exclusively through Enigma. The data went to Berlin, but neither the Germans nor the British received any reaction.
