Duan Yun still understands passwords.

To put it simply, a password is a technique used to obfuscate users who want to turn normal information into unrecognizable information. But this unrecognizable part of the information can be reprocessed and recovered and cracked.

Cryptography was first used in the military, especially in modern warfare, in order to prevent the other side from intercepting their own call information, the two sides used mathematics to encrypt or decipher important information, forming a new applied mathematics - cryptography, that is, cryptanalysis and information security design.

Cryptography is the core technology of information security. With the rapid development of modern computer technology, cryptography technology is constantly penetrating into more and more fields. It is an interdisciplinary discipline integrating mathematics, computer science, electronics and communication. The use of cryptography can not only ensure the confidentiality of information, but also ensure the integrity and confirmation of information, and prevent information from being tampered with, forged and counterfeited. At present, the core topic of cryptography is mainly to study various provable security systems for various active attack behaviors on the basis of combining the specific network environment and improving the computing efficiency.

Cryptography itself is a sub-discipline born from mathematics, so Duan Yun, as a master of mathematics, naturally has a very comprehensive understanding of cryptography.

In the password puzzle provided to him by Guo Haitao, there are many binary digits that have been encrypted in the attachment, which looks quite messy and has no clue at all.

For ordinary people, this kind of cipher is definitely a heavenly existence.

Although there are also a wide range of uses in Internet commerce, such as the MD5 encryption method of irreversible operation, Duan Yun saw at first glance that this level of encryption is definitely military-level, but it should not be regarded as an advanced password.

According to Duan Yun's understanding, the military-grade cryptographic encryption method is the top national strategic-level secret in any country, and in terms of secrecy, it even surpasses the manufacturing technology of nuclear weapons!

The importance of military ciphers is not understood by ordinary people, but it can be glimpsed from some news and film and television programs.

A few years ago, China had introduced a large-scale film "Hunting U-571" with the theme of World War II, which mainly told the story that during the Second World War, Germany's submarine wolf tactics blocked the British coastline at the beginning of the war, sinking hundreds of Allied merchant ships transporting supplies and equipment, which once dealt a major blow to the British military.

Later, in a fortuitous naval battle, the deep water* of the British destroyer hit the German U-boat, and the submarine with a wounded hull was forced to surface, and was finally captured by the Allied Chen Gong.

To the great joy of the Allies, in this submarine codenamed U-571 that was forced to surface after being hit by a bullet, the Allies accidentally obtained a intact Engoma cipher machine, and after the research of British mathematicians, they finally cracked the military code of the German army!

Cracking the German military code is of great significance to the Allied forces, which also allows the Allied forces to obtain a large number of German top secret and key strategic deployments in the later war, so that the Allied forces have gained the initiative in the war, whether it is the later Soviet-German war or the Normandy landing of the Anglo-French coalition army, it has played a vital role!

And many post-war military scientists also believe that cracking the German Engoma code shortened the course of the war by at least two to three years, or even longer, and saved tens of millions of lives, which shows the importance of cracking the military code!

As for the military in China, the degree of secrecy of military passwords is even more rigorous to the point that it is sent, and usually there are confidential staff officers in charge of secrecy in regimental-level combat units, and the encryption keys at the division and regiment level are basically changed every six months, and these secrecy cadres are required to go to Kyoto in person to collect them, and the procedures are so strict that they are outrageous!

As for the military-grade password provided by Guo Haitao, in Duan Yun's opinion, it should belong to a foreign army.

Generally speaking, the military password encryption method of various countries has a relatively long period of unblocking, and the fastest will appear in the media in half a century or even longer, while Huaxia has never decrypted any relevant military password encryption method since the founding of the People's Republic of China.

It can be seen that the military password in Duan Yun's hand is likely to be the password encryption method used by foreign armies decades ago, or even during World War II!

But even this kind of military cipher from more than half a century ago. For Duan Yun, it is still an unprecedented and powerful challenge.

At first, Duan Yun tried to calculate by hand with paper and pen, but he soon found that the amount of calculation was too large and complicated, and even in his opinion, even if he had master-level mathematical mastery, he would have to count it for more than a hundred years without eating or drinking, and this was only the first step in it!

In addition, because Duan Yun did not have a complete cipher machine like the British mathematicians of World War II, if he wanted to crack this kind of code, it would be several times or even dozens of times more difficult than those British mathematicians of World War II!

For a while, Duan Yun was a little helpless, and even fell into an impasse in solving the problem.

However, Duan Yun quickly thought of other ways.

Although he was a little unwilling, Duan Yun felt that this kind of code decipherment could only be done with the help of a foreign object, that is, a computer.

As long as you set up a correct program to calculate and crack the password, the computer will be able to perform the operation at a much faster speed than ordinary people, which can save a lot of time.

However, using a computer to crack a password also requires technology, at least in terms of programming, Duan Yun must be able to independently write some relatively complex calculation programs.

However, there is no need for Duan Yun to teach himself relevant computer technology, because he has a 'super five good students' system that defies the sky.

With a move in his mind, Duan Yun quickly opened the 'Super Five Good Students' system in his mind.

Since he rescued Yang Ying in the last Beiyuan fire and almost died, the achievement system in Duan Yun's mind no longer prompts the achievements obtained, and now Duan Yun basically doesn't need any new skills, so he has basically not used this system for a while.

But now in the face of the password question given to him by Guo Haitao, Duan Yun urgently needs to master the programming technology of the computer, so he opened the system again.

However, when Duan Yun saw the system for the first time, he was immediately stunned by the scene in front of him.

At this time, in the skill point column of his system, there were as many as 11,000 skill points that had not been added!

And in Duan Yun's achievement system column, it shows that he won some achievements such as 'First Continental Championship' and 'Million Fans', which is obviously his achievement through his highlight performance in the last East Asian semi-finals!