Tech Hammer

The afternoon class is number theory and cryptography, which is a professional elective course.

However, generally speaking, students majoring in applied mathematics will choose this course. After all, there are 48 theoretical hours and 4 credits, which is very cost-effective.

As the name suggests, this course is about the application of number theory in cryptographic systems, which is a branch of applied mathematics.

It's just an undergraduate course, so it's not very in-depth. Basically, it just talks about the development history of elementary number theory and cryptographic information. In fact, it's very interesting to learn it. Even the most basic Caesar cipher can be played. Can tell a story.

The afternoon class time of Jiangda is 2:05.

Ning Wei was already ten minutes late when he arrived at the classroom.

What's even more annoying is that the back door is locked.

When Ning Wei was standing at the front door hesitating, thinking about skipping class altogether, by chance, the teacher on the podium called his name.

"Ning Wei, let me answer this question."

Ning Wei, who was standing outside the door, hesitated for two seconds. Is it such a coincidence?

"Huh? Ning Wei didn't come?"

Annoying!

"Professor, I'm here." Ning Wei stood at the door with a red face, which was met with a burst of laughter from under the podium.

"Um?"

Professor Chen on the podium pushed up his glasses and glanced sideways at Ning Wei, who was standing at the door holding a laptop bag. He lost his temper and became happy: "Eh? Are you Ning Xueshen? By the way, are you calculating? Will I order you today? Are you here specifically to cooperate with me? "

"Professor, Director Li asked me to deliver some materials to him, so I'm late."

"Oh, okay, come in and take a look at this problem. How to solve it?"

I walked into the classroom amidst the laughter of my classmates, glanced at the content of the PPT on the projector, and saw elliptic curve encryption.

Soon, the basic operation rules of elliptic curves were sorted out in his mind, including addition, doubling operation, negation of positive and negative, infinite point, finite field...

Then the problem-solving process and the answers appear naturally in my mind like breathing.

"Report to Professor, because the elliptic curve y= x+ ax + b on the finite field GF(p), if P(Xp, Yp), Q(Xq, Yq), and P≠-Q, then R(Xr, Yr) = P+Q should be determined by the following rules..."

"Wait a minute, I don't remember you, come to the podium and write on the blackboard." Professor Chen stopped Ning Wei directly.

Helpless, Ning Wei put his notebook on the desk, picked up the electronic pen, and started writing on the blackboard.

"Xr =(λ- Xp - Xq) mod p

Yr =(λ(Xp - Xr)- Yp) mod p

Among them, λ=(Yq - Yp)/(Xq - Xp) mod p (if P≠Q), λ=(3Xp+ a)/2Yp mod p (if P=Q)..."

Soon, after several steps, the conclusion was drawn that 3G is point (3, 13).

"Well, the explanation is very good, the thinking is very clear. Oh, the teacher is really honored. It seems that I have studied this book by myself before, no wonder I dare to be late. Okay, go find a seat and sit." Professor Chen waved Wave.

Ning Wei was granted amnesty, picked up the notebook, and got into the back row.

Generally speaking, even if he doesn't come, the brothers in the dormitory will help him occupy a good position.

Sure enough, as soon as he arrived at the back row, he saw Luo Xiang waving to him. Ning Wei immediately got in and had just finished it. Before he could take a breath and tell a few people the good news that they were being targeted, the professor on the stage came again. spoke.

"Ning Wei, why are you traveling so far? Forget it, I won't argue with you. Let me tell you, one of the topics I am studying is the fuzzy continuation method of pseudo-Boolean function N-person games. It is very interesting. If you are interested , call me later. I will help you write a report and apply for a direct PhD quota."

"Wow……"

There was a burst of envy, jealousy and hatred in the classroom...

Ning Wei was dumbfounded, but it was obvious that Professor Chen didn't intend to wait for his response. He operated the computer twice, skipped the previous question, and turned to the previous content: "Okay, let's start the class now according to the routine. Just now The elliptic curve encryption content of Ning Weijie was only taught in the last few classes, and the difficulty was raised. So this order is wrong, just take a look at it, it doesn’t matter if you don’t understand, what we are going to talk about today is the primality detection algorithm.”

"I would rather not listen, but I suggest that others still listen carefully. Because I got the news before class, many of our professors think that the quality of your students is very high. It can be said that there are hidden dragons and crouching tigers. It is no exaggeration to say that several The professors all think that you may be the best class we have ever taught!”

"So the overall difficulty of this year's final exam will be higher than in previous years, and it will probably be closer to that of the base class. Other professors have raised the difficulty level, and it would be a bad idea if I didn't raise the level of difficulty for everyone. It would make me seem less gregarious, and it would make me even more difficult. I look down on you, right?”

"wrong!"

Upon hearing the bad news, a group of poor children under the podium responded in unison, and then quickly became confused: "Professor Chen, please, don't you look down on us?"

"That's right, what kind of rhetoric is this? Professors, don't do this!"

"Not everyone is as perverted as Ning Wei!"

"Professor Chen, we are just children! Normal children!"

"I would rather have only one, but there are many ordinary people! If you make it more difficult, people will die!"

It’s really wailing all over the place...

In particular, Xu Ruixuan and Luo Xiang, who were beside Ning Wei, shouted the most enthusiastically, and Liu Cong also complained. Ning Wei then discovered that Liu Cong went out early in the morning to get a haircut. He changed his hair to a short one and looked more energetic.

Professor Chen stood on the podium and smiled without saying a word until the noise finally subsided. Then he raised his hand and suppressed everyone's enthusiasm. A warm smile like an aunt appeared on his face: "How could that be? We got it." Secret information, you kids, you usually talk about how difficult this is and how difficult that is in class, and the exam should be easy, but in private you study such advanced things as automorphic functions, Howe dual conjecture, matrix coefficients, and Ramsey two colorings. It’s not just Ning Wei!”

"So the difficulty will definitely increase this year, and the graduation thesis will also put forward higher requirements for everyone! Okay, stop making trouble, now I have to officially start the class! Before learning the primality detection algorithm, what do we need to know first? It's called primality testing. As the name suggests, it means to determine whether an integer is prime, which is called primality testing..."

Professor Chen began to teach formally, while the three people around Ning Wei were dumbfounded.

The difficult problems Professor Chen mentioned just now are all very familiar.

Of course, it’s hard even if you’re not familiar with it.

The three of them had read the article together at least ten times each. Although the difficult questions were found by looking for reference books everywhere, they naturally remembered it after reading it more than ten times.

Of course, there are more than just a few difficult problems in mathematics, but these few problems happened to be chosen by three people.

Just right, a bit worse than that kind of world-wide problem...

so……

"What a paralysis! Are professors so free? Don't they have to do research? They still have time to browse Zhihu? How is it possible!" Xu Ruixuan, the author of the article, sighed in shock.

Ning Wei glanced at Liu Cong, who also had a melancholy look on his face, thought for a while, and still didn't say anything.

Yes, professors will most likely not have the time to pay attention to Zhihu, but who makes you like Xianbao so much?

When Professor Chen on the podium finished speaking, many people turned their heads to the back row and focused on the other three people in 302...

Obviously, many of the classmates have seen Xu Ruixuan's masterpiece and were deeply impressed.

Get rid of it!