Like many other pre-war theoretical developments of the leadership of the Red Army, the system of government communications in combat conditions showed itself not from the best side. In particular, the overhead HF communication lines were located near railways and highways, which were among the priority targets of the enemy. A massive artillery strike or air raid destroyed both the road and the secret communication lines. Negatively affected the survivability of government communications and the almost complete absence of backup, bypass, ring and rockade lines that could help in critical moments. In addition, all HF communication equipment was very cumbersome and was located in the administrative buildings of the NKVD in large settlements, which often fell under the priority attack of the Germans. There was no need to talk about any mobility of communication even between the High Command, the General Staff and the headquarters of the fronts.
And how did communications function at the level of division commanders? It was assumed that the divisional commander of the Red Army in a combat situation should look for the nearest settlement with a working HF communication center. Then he sends a messenger to the "subscriber", for example, the regiment commander, with instructions to find the HF communication center nearby. The promptness of decision-making and their execution suffered from such rushes to the full. Such a situation could have been saved by the field means of encrypted communication, but, unfortunately, they were practically absent, and if they were, then at the commanders of the fronts and armies. Such a deplorable situation often led to the actual loss of command and control of the Red Army troops.
Presumably one of the few photographs of the S-1 "Sobol-P"
A problem of this kind began to be solved as early as 1938, when in the laboratory of V. A. It was a very complex HF radiotelephony technique, which in many respects had no analogues in the world. "Sobol-P" used time and frequency permutations, and as a scrambler was used the telegraph tape mentioned in other articles of the cycle with random perforations. Kotelnikov's team, already three months after the outbreak of the war, began initial testing of individual Sobol-P components: a frequency permutation node with spectrum inversion, a temporary permutation node, a transmitter-based encoder unit and a five-line perforated telegraph tape. It is noteworthy that in the course of such unique works, new technical solutions were born almost every day, which had to be recorded, published and patented. But in the conditions of war there was no time for this: everything in the laboratory was subordinated to the creation of a new generation of telephone conversations encoder. And all the works were classified, seriously limiting the dissemination of information.
In the book by Vadim Grebennikov “Cryptology and Secret Communication. Made in the USSR”provides an example of the development of a temporary reshuffle unit, which very clearly describes the difficulties faced by the developers. The design of the node consisted of two objects: a device for slowing down the speech signal by 100 and 200 milliseconds and a circuit for switching delayed signals, which permuted 100-millisecond segments of speech. Engineers working with V. A. Kotelnikov, considered several options for slowing down sound signals. In the first version, they took a rubber hose 33 meters long, fed an audio signal from the speaker to the input, and at the output a microphone with an amplifier recorded the deceleration of the sound by the required hundred milliseconds. However, the cumbersomeness of such an execution, as expected, put an end to the idea. In the second version, it was proposed to use a Swedish narrow and thin enough steel tape for magnetic recording. Struggling with the dimensions of this design, the tape was pulled over the drum in the hope of ensuring a smooth joint. But everything was spoiled by the click that occurs when the joint passes through the pickup mechanism. Attempts to overlay several turns of tape on the drum rim and record in the center of the multi-turn "winding" also did not give good results, since the adapter, passing along the junction of two turns, created interfering noise. On the third run, the goal was to reduce seams and repetitions of interfering clicks. The engineers used a long loop for this, which was passed through many rollers. There was an inverse relationship between the length of the loop and the number of clicks - the longer, the less clicks. But everything rested on the cumbersomeness and serious noise generated by the moving steel belt - as a result, all developments were shallowed as unpromising. In idea number 4, it was generally proposed to use … a circular saw with a ground plane, on which the information was recorded. Of course, all the teeth were previously removed. Everything worked in this version, there were no clicks, but the speech quality left much to be desired. As a result, the disc was left, but they decided to write not on the plane, but on the rim. True, for the magnetic recording it was necessary to look for high-quality steel, which was found at the "Hammer and Sickle" enterprise in Moscow. These were experimental brands EKh-3A and EKh-6A. This is how one of the complex nodes of the future Sobol-P telephone encryption device was born. Engineering searches in Kotelnikov's laboratory clearly show the level of technological development at which the industry of the Soviet Union was at that time.
The first successful tests in real conditions S-1 "Sobol-P" took place on the radiotelephone line Moscow - Khabarovsk. In a combat situation, a unique apparatus was tested on the communication line between the Headquarters of the Supreme High Command and the headquarters of the Transcaucasian Front, since the wire HF communication between them was disrupted during the hostilities. It was "Sobol-P" that for the first time transferred communications of this level from a wired basis to a radio channel.
Medal of the Stalin Prize, 1st degree, which was also awarded for the development of Sobol-P. In 1943 and 1946
In 1943, Kotelnikov improved his brainchild, produced at a plant in Leningrad. The head of the laboratory repeatedly flew to the besieged city to set up production on the spot, while his plane regularly came under fire. The Sobol-P equipment was actively used during the preparation of the Battle of Kursk and during the battle itself, which largely determined the victory in this sector of the front. Until the very end of the war, the Germans could not reveal the principle of operation of the Kotelnikov encoder. And, according to Soviet intelligence, Hitler repeatedly said that he would give three of the best divisions of the Wehrmacht for one cryptanalyst capable of hacking the "Miracle Sable".
Such design successes could not pass by the leadership of the USSR, and in March 1943 V. A. Kotelnikov, D. P. Gorelov, I. S. Neyman, N. N. The engineers traditionally donated all the funds received to the troops, and they collected a tank for the Kotelnikov prize.
"Live broadcast" for Moscow from the signing ceremony of the act of unconditional surrender of Nazi Germany was carried out on C-1 "Sobol-P"
Until the very end of the war, "Sobol-P" was used on all fronts to organize communication with the High Command of the Red Army. The Tehran, Yalta and Potsdam conferences also did not go without the encoder of Kotelnikov's team. And finally, the apotheosis of the Sobol-P apparatus's career was its work in May 1945, when Moscow kept in touch with Berlin during the unconditional surrender of Germany. After 1945, the equipment was used on radio communication lines between Moscow and European capitals. The potential for the modernization of Sobol-P was so great that work on its revision continued after the end of the hostilities of World War II, and in 1946 the entire engineering staff was re-awarded the Stalin Prize of the 1st degree.
The work on the topic of secret telephony in the USSR until 1946 resulted in a huge amount of development work, which later became the foundation for deeper research. In addition, the special services and troops have accumulated valuable experience in the operation and maintenance of such equipment, which had a positive effect on further developments. And finally, the first teams of professionals have appeared, from which in the future will grow into large organizations producing world-class encryption technology.
To be continued….
