"Why did it stop?" The boring and unrelenting work lasted for two days, and during a drone cruise, Cortana suddenly turned off the signal transmission interface with the repeater. As a result, the rover lost contact with the two drones that were still cruising over the airport. Gou Ke, who was tired and about to fall asleep in the middle of the day, knew that something had happened, so he immediately came to his senses and hurriedly asked Xiao Na.

"Twenty minutes ago I received a messy signal from the repeater, and I thought it was just interference from the cosmic microwave background radiation so I skipped it, but twenty minutes ago I received another messy signal with a lot of duplication from the first one. For the sake of prudence, I have backed up these two signals for comparison. Then, not surprisingly, I also received a new message that partially overlapped with the previous two messages. "I'm guessing someone is repeating a signal through the repeater every 10 minutes." This means that there are other people besides us who are using repeaters. ”

"You're saying it's possible that we've been discovered by the enemy?" I don't know much about communication, but it doesn't sound good.

"Yes, so in order not to reveal our location, I temporarily turned off the signal interface. But it doesn't have to be an enemy, you can compare the signal characteristics with those people in the National Front to see if they are familiar. After Xiao Na finished speaking, the printer popped up a USB flash drive, "I changed the USB flash drive drawing, and when it was printed, the three pieces of information were burned on it."

Without hesitation, Gou Cao immediately went to find Wu Zhe.

"Arirang, come here." After Wu Zhe understood the situation, he beckoned and called a younger young man to come over.

This person named Arirang is an ethnic Korean, and his nickname comes from this. His real name is Hao 囏 (pronounced jian, four tones. ）。 The name is difficult to recognize and the pronunciation is awkward, so both myself and others prefer to call him Arirang, and over time, everyone forgets what his real name is - except for the harshness of looking at the personal files of everyone present. If Gou Ke remembers correctly, Arirang is a communications soldier.

"I don't know much about encrypted signals or something, and Arirang is an expert among several of us in this regard. Let him compare. After Arirang came over, Wu Zhe introduced Arirang to Gou Cao. Wu Zhe handed over the USB flash drive. It seems that Wu Zhe did not know that the commander had provided Gou Cao with their personal files.

After Arirang received the USB flash drive, he inserted the USB flash drive into the backpack-sized team portable communication device. Begin the comparison of traits and characteristics. It soon came to the conclusion that it was indeed a communication signal used within the National Front.

"And what does this signal mean?" Gou Cao just wanted to ask, but Meng Jie, who was on the side, asked first.

"I can't figure this out." Arirang responded.

"Don't you even have a codebook?" Meng Jie looked a little anxious to listen. Only then did Gou Cao remember that Meng Jie, who had been in charge of public security all year round, now ran out behind enemy lines, probably mainly because there were his best friends among the few people who disappeared in the previous operation. (The codebook is just a colloquial term for a decryption algorithm, not necessarily an entity.) ）

"No, I brought it, this codebook is also used to contact the Dunan stronghold during this time." Arirang's personality itself is a little shy, and now he is a little embarrassed by Meng Jie's aggressiveness.

"Xiao Meng, sit down and let him finish." Seeing this, Wu Zhe held down Meng Jie.

"The problem is that this signal is obfuscated in addition to the usual algorithmic encryption." Arirang continued to explain after seeing the emptiness. "So before decrypting according to the codebook, it is also necessary to filter out redundant information that has been added for confidentiality. This requires two things, a deblurring algorithm that filters out this redundant information, and a high-performance computer that can perform deblurring calculations. ”

The so-called fuzziness is to add some redundant meaningless information in addition to meaningful information, such as the Morz code of the target is "-.-.-.--.. - "Then a simple fuzzy process is to insert a random paragraph of nonsense in the middle of it." or "-" resulting in the inability to translate or mistranslate the meaning of the Morz code in the translation of the paragraph.

The advantage of this processing is that it makes the entire piece of information look disorganized, like simple gibberish. Moreover, even if it is the same sentence, a large part of the message sent each time is different, which increases the difficulty of deciphering. This is also the reason why the three messages Cortana received before were only partially repeated, but Cortana still thinks that it may be the reason why the same paragraph has been sent many times.

However, the disadvantage is that the inverse operation of some fuzzing algorithms is quite complex, and even if there is a corresponding defuzzing algorithm, it requires a considerable amount of computation. As a result, this processing was invented in 2020, but it was not put into practical use until 2030, when military-grade high-performance computers began to enter service in large quantities. This is also the reason why defuzzing algorithms require high-performance computers.

"Where are I going to get these two things?" Wu Zhe's question is simple and direct.

"The deambiguation algorithm is still stored in my communication device." Arirang paused for a moment, "But the high-performance computer was too cumbersome to carry in a car, so we destroyed it together when we abandoned it." And the high-performance computers at this post were also removed when the previous group of people monitoring the airport were evacuated."

"Copy the algorithm into this USB flash drive, and I have a high-performance computer in my car...... I used it to install an automatic cruise system for the rover. "Of course, they can't tell them that there's an artificial intelligence on the rover, and that the current carrier of this artificial intelligence is a supercomputer.

Soon, Gou Cao returned to the cockpit with a USB flash drive equipped with a deblurring algorithm, and with the help of Cortana, the signal was quickly decrypted.

It's a coordinate.