Zhang Weiping left, and there were few people left in the office.

Liu Lu of NTU is still there, the youngest full professor of mathematics in China, who is crawling in front of the computer and doesn't know what he's busy with.

Professor Mokomo of Nanyang University, who had asked him about the core of the Dirichlet function of the simplified method, was still there, and he was frowning at his desk calculating something.

The remaining two, he didn't know.

Retracting his gaze, Xu Chuan focused his attention on the original ciphertext in his hand.

He wasn't very familiar with cryptography and cryptography, and some of his knowledge was limited to common sense.

For example, asymmetric encryption, symmetric encryption, hash algorithm, MD5 encryption, SHA1 encryption, etc.

He knows a little about these common encryption methods, but not much.

However, from a mathematical point of view, there is no way to prove that an algorithm is 'absolutely safe'.

Of course, the proof of security in practice is the fact that it was 'never compromised', and there are still that.

In the past, people thought that the DES encryption system based on symmetric encryption algorithm was very secure, but with the development of modern computers, the computing performance of an ordinary person's home computer can easily crack it brute-forced.

Nowadays, we believe that AES, RSA, and elliptic curve encryption algorithms are safe, after all, there has been no news that these encryptions have been broken.

But in reality, these encryption methods are not completely secure.

For example, if RSA is not populated, then an attacker can greatly reduce the space for decryption by observing the ciphertext of a particular plaintext.

Or if AES encryption is the most primitive mode, then the same ciphertext will correspond to the exact same plaintext.

On top of that, some machines don't generate passwords randomly enough, resulting in keys that should be randomly distributed all of them being identical.

These are flaws.

Xu Chuan doesn't know much about encryption, and these are not things he needs to care about.

Because in this building, the most elite cryptography experts in the 9th arrondissement are gathered.

For example, Academician Wang Xiaoyun, a top cryptography expert, has single-handedly made the cryptography of Yuxia Kingdom in the ninth district a leading position in the world.

In the early years, District 1 claimed to have developed a set of MD5 encryption algorithm technology, claiming that it was the most secure algorithm in the world, and claimed that "no one will crack it for 100 years".

This attracted the attention of the world, and many experts in the field of cryptography competed to study it, and some scientists led their teams to study for more than ten years without success, and the result was easily deciphered by Wang Xiaoyun.

Later, after knowing that MD5 was cracked, the first area urgently came up with another set of top encryption algorithms, SHA-1.

SHA-1 is more powerful and complex than the previous MD5 algorithm, and countless top cryptographers have come to challenge, most of them have no way to advance after 40 steps, but Wang Xiaoyun still cracked it easily.

And the reason for this crack is to make the first district vomit blood, and the reason is simply because the password goddess was bored during the confinement, took out a pen and paper to write and draw, and then it only took two months to crack this extremely complex encryption algorithm.

With such top talents, Yu Xiaguo's network security is solid.

But today, the first side has once again upgraded the encryption algorithm.

Not only the rules and algorithms have been redesigned, but also the huge functions have been double-encrypted.

This kind of encryption method is no longer a simple cryptography, it involves other aspects of knowledge, even the top cryptography experts, even the goddess of cryptography, is unable to break this kind of encryption information alone.

Fortunately, Xu Chuan does not need to worry about cryptography and encryption.

He only needs to find the law behind the encryption of the double function algorithm and build a mathematical model in a targeted manner.

For this, Xu Chuan still has enough confidence.

Twenty years later, he didn't major in mathematics in his previous life, but in Princeton, he had access to the world's top and most cutting-edge mathematical knowledge at any time.

In Princeton, countless mathematical conferences are held every year, and countless geniuses and mathematicians are there to pass on their ideas and achievements.

Those advanced function knowledge and achievements are naturally among them.

From the early days when Galileo defined functions, functions never withdrew from the core stage of mathematics.

If mathematics is the foundation of all disciplines, then functions are the soul of mathematics.

The essence of a function is to try to establish a mathematical tool that describes the 'causal relationship' between related things.

Causality is one of the most important laws for human beings to perceive things.

In simple terms, discovering and describing the laws of cause and effect can give humans the ability to "predict" things.

For example, if a function describes the motion of a car, as long as the independent variables of the function contain rich parameters such as time and speed, we can go back to 5 minutes ago or predict where the car will be in 5 minutes.

If it's a little more complicated and loaded with more parameters, the function can even predict a person's actions, and what time you'll be doing tomorrow.

Before the invention of this mathematical tool, it would have been almost impossible to describe this relationship precisely.

......

In the mathematics room of the Information Security Division, Xu Chuan listed the information in his hand on the table in front of him.

On one side is the original ciphertext, and on the other side is the translated mathematical puzzle, each of which is unique and without any repetition.

Xu Chuan carefully studied the mathematical problems after the transfer.

From the basic exponential functions, logarithmic functions, power functions, trigonometric functions, inverse trigonometric functions, ..... to complex hash functions, symmetry functions, Gaussian functions, max, min functions, Euler functions, and so on.

These mathematical puzzles include a wide variety of functional puzzles.

But he was not frightened by complex and changeable functions, Xu Chuan knew very well that no matter how complex the functions were, most of them were composed of basic functions.

Although there is no pattern to these functional problems in front of us, the first side of the first region can use these various functional problems to encrypt messages, and can send a large number of useless messages to interfere with other countries, and must have in their hands the mathematical laws that generate and create various functional problems in large quantities.

He didn't believe that an ordinary person on a mission had the mathematical ability to decipher and solve these mathematical puzzles.

So sink your heart and take your time to look for it, and you will definitely find a clue.

Although from a mathematical point of view, perfect things exist, they cannot be created in reality.

It's like there are definitions of infinity and infinitesimal in mathematics, but can you write a number that represents infinity or infinitesimal size?

It's simply not possible.

.......