Chapter 248 The fastest hole filled
The people from Changjian Factory and the users happily left the Third Rolling Mill with their achievements and went back to work.

Gao Zhendong continued to post messages in the factory, and there were quite a lot of people.

Lao Chen has already said it separately that it doesn't matter whether he posts or not. Master, you are already a mature parent of the boy, and you should learn to keep track of the dates yourself.

There are others such as Director Yang, Deputy Director Li, acquaintances in the Technical Department, acquaintances in the Security Department, and many acquaintances in the workshop, all of whom I met while making products.

Gao Zhendong also notified Yu Yuncheng and the others. They came all the way from the mouth of the Haihe River, not far away, so they wanted to feel the warmth of a big family. The single crystal furnace they were working on together is almost successful, but judging from Yu Yuncheng's look, he plans to wait until Gao Zhendong gets married before completing the project, giving Gao Zhendong a double happiness.

However, Gao Zhendong did not notify everyone he knew, as that would seem too shameless to others. He would only notify those he knew and was familiar with and had a good relationship with.

For example, Old Yuan, who had been punished by Gao Zhendong several times in the Technical Department, was too lazy to say a word.

As for other factories and institutions, not many people needed to be notified. For example, the Computing Institute and the Beijing Iron and Steel Plant only notified familiar leaders, while ordinary employees and middle-level managers were not notified. It was not because they looked down on them, but because they were afraid that others would think too much. Besides, in this day and age, making a big fuss is not a good thing.

In the midst of this busyness, someone from the National Defense Committee arrived on Wednesday. They were brought by someone from the confidential office, and they first verified the identity of the visitor.

Seeing that they were brought by the confidential office, Gao Zhendong verified their identities again with the Defense Work Committee and invited them to his office.

The visitor looked embarrassed: "Director Gao, you are busy getting married these two days, and we are sorry to bother you again. I wish you a happy wedding in advance and congratulations."

It seems that the leaders of the Defense Work Committee have given notice. Gao Zhendong doesn't care. Even if you don't come, I still have to go to work. It's impossible for me not to work for a week. How can I be so confident as to do that?

"Thank you, thank you. There's nothing to be embarrassed about. We have to do our work. What is the reason for your visit this time?"

"Director Gao, do you remember that when we were doing a data telecom test last time, our leader asked you to develop a data encryption program to solve the confidentiality problem in data transmission?"

Gao Zhendong exclaimed, "Ah!" and remembered.

"Yes, there is such a thing. How come you have already determined the demand?"

"Yes, this is our idea, take a look."

Gao Zhendong took the document, opened it and started reading.

The requirements are not complicated, they are basically symmetric encryption requirements. DES is very suitable for these requirements and is not difficult.

In simple terms, in information technology, symmetric encryption is the most familiar encryption method. The same or the same set of keys are used to encrypt and decrypt data. Decryption is the inverse operation of encryption. Common compression software such as Rar, Zip, and 7z use this type of encryption.

The advantages are that brute force cracking is difficult, the amount of calculation is small, and the encryption and decryption speed is fast. However, there is a fatal flaw. The difficulty of brute force cracking does not mean high security. The biggest weakness of this method lies in the management of keys, especially in situations where keys need to be changed frequently. How to securely send the keys to the other party becomes a problem.

In practice, some people have tried to use an extremely complex root key to manage the transmission of keys. However, in fact, this root key itself becomes a weakness. As for how to ultimately solve this problem, that is another story.

However, for the current National Defense Committee and related units, key management is solved through management means. For such needs, they have a large number of mature means to use.

It's not as abstract as the Citigroups, where the strategic ballistic missile launch code is just a few zeros or 0.

It’s not that the National Defense Committee does not want to use asymmetric encryption public key algorithms, such as the international RSA and the national SM2 and SM9, but because they simply cannot imagine that such things actually exist. This is the limitation of the times.

However, although both SM2 and RSA of the National Security Agency are public key algorithms, they are very different. The former is based on elliptic curves, while the latter is based on large number decomposition.

Gao Zhendong didn't think of proposing asymmetric encryption right now. The amount of computation required by these encryption methods is much greater than that of symmetric encryption, and current machines cannot support it.

He read the entire request and smiled, saying that this was an easy thing to do.

He called the Defense Work Committee again and verified the identity of the person who came, mainly to verify whether the relevant things would be handed over to the person this time. Given the purpose of these things, it would not be excessive to be cautious.

Although the DES algorithm itself will be made public in the future, it is still better to follow the relevant requirements at this time.

The people who came were also smiling and very cooperative. In their opinion, Gao Zhendong's behavior was perfectly normal.

After verifying the relevant matters, Gao Zhendong turned around, opened his safe, and took out several things from the storage without telling the person who came.

One tape, two paper documents.

"This is the encryption program I have written. There are two paper documents. One is the principle and description of the algorithm, and the other is the program source code and instructions for using the program."

Gao Zhendong spent most of his day after the meeting to finish this. The procedures were all standard procedures, so it didn't take much time. Instead, it was the two paper documents that took time. Because there was no printer yet, the source code and related instructions were all handwritten, which made him exhausted.

He even thought about going to the computing center to urge the progress and act as a supervisor. I said at the meeting that it would be solved in one day, so it only takes one day!
The visitor really didn't expect that this matter would not need to be left overnight, and Gao Zhendong solved it on the spot.

"Director Gao, have you done it? Is it worthy of this request?"

It is normal to have this worry. After all, we have made the product without having seen it or considered the demand.

Gao Zhendong nodded: "I have checked it. This program can meet the requirements you brought over. There is no need to modify it. You can show it to the relevant experts and they will know. If you still have questions, come back to me."

In fact, this is also related to the fact that the National Defense Working Committee has difficulty proposing specific algorithm indicators due to its unfamiliarity with computer-related technologies and concepts.

For example, the simplest one is the key length issue. In fact, they didn't even think about it when they proposed it. They can realize the relationship between key length and encryption strength, but they can't quantitatively stipulate the key length. They can only qualitatively describe it as "the key length should meet the requirement of preventing traversal means from cracking within XX time."

Therefore, after Gao Zhendong fully evaluated the requirements submitted by the Defense Work Committee, he immediately took this thing out. There was no need to modify it. It was perfect.

Seeing that Gao Zhendong was full of confidence, the people from the Defense Work Committee didn't say anything more and said, "As long as you are sure, I will take you away."

After signing the relevant formalities, the visitor sealed the three things. From this time on, none of them could open the seal, not even Gao Zhendong himself.

This gap was filled quite quickly, Gao Zhendong thought.

With the things, they quickly returned to the Defense Work Committee.

On the side of the Defense Work Committee, the relevant personnel had already been prepared and had been waiting for a long time.

They were the relevant personnel who came to discuss the needs of encryption software. Before they left, they heard the report that the things had been obtained, so they decided to work overtime. They were also very curious about what the things that were produced in one day would look like and what the effects would be.

After a series of handover procedures, people opened the seal and took out the three items.

"Instructions for the National Secret-1 (GM-1) Symmetric Encryption Algorithm", "Instructions for the Use of the National Secret-1 (GM-1) Symmetric Encryption Software", and a tape.

"Haha, the name is well chosen, grand and simple." Someone laughed.

The leader of the Defense Work Committee didn't know how to respond. Based on his understanding of Gao Zhendong, this guy was just bad at naming and this time it was purely luck.

Mathematical experts first look at the algorithm description, while computer technicians look at the program instructions and prepare to run the encryption program.

Several mathematicians nodded as they looked at the algorithm.

"Well, this algorithm is very good. It doesn't have any obvious weaknesses. From a preliminary look, if you want to crack it, you can either start with the key or use traversal."

"Yes, it seems that the algorithm itself has no loopholes. Moreover, the amount of calculation required for encryption and decryption is not large, which is compatible with the current computer speed."

"The best part is that this algorithm is very suitable for the binary operation of computers. It is different from the general addition, subtraction, multiplication, division, exponentiation, and square root operations. The algorithm is more complicated, but it is very suitable for computers."

"You know what? If I were to design it, I really wouldn't be able to do it so well. I may be better at math than the designer, but I'm really not as good as him at computer math."

"I heard that it was developed in one day? What a genius! Just designing this algorithm would not be something that an average person could come up with in a day or two."

It is indeed difficult to design something, but it is much easier to copy it.

"A 7-character key supports letters, numbers, and special characters, which is a wide range."

The DES key is 56 bits, which is exactly 7 bytes.

"The case of letters is also sensitive, so the scope is even greater."

"."

The leader of the Defense Work Committee was smiling. It seemed that Gao Dapao really did not fire blanks. What he said was a day really came true. As soon as people went there, the results came back.

Soon, the computer technicians got the program running and began relevant tests.

The encrypted file was not large, only about 1 words and 20kByte. After a while, the operator reported: "Encryption completed. There is no direct correlation between the ciphertext and the plaintext."

This is only temporary, and the details still need to be tested multiple times.

(End of this chapter)