my scientific age

Chapter 110 Hill Password!

Participate in the work of cracking Japanese ciphertext, yes.

Participate in other affairs of the Blue Shirts Secret Service, no.

This is Yu Hua's bottom line.

"We are all people who help the country with knowledge."

Hearing Yu Hua's remarks, Hua Luogeng's young and tired face showed a smile, and replied in a straight voice: "From tomorrow onwards, we will add cryptography courses, take a break today, and you will study later."

"Yes, then I'll go back to the second bed first, and I will teach you to pay attention to rest." Regarding the upcoming deciphering Japanese ciphertext work and cryptography courses, Yu Hua's face showed a look of anticipation, nodded, and reminded Hua Luogeng, who was exhausted. .

Hua Luogeng smiled: "Okay."

After the conversation ended, Yu Hua bid farewell to Hua Luogeng, got up and left the study.

Go back to the second bedroom.

"Cryptography, deciphering Japanese ciphertext, life has become more interesting. I don't know what this job is like. I hope I can do it." Yu Hua returned to the seat, thinking about it in his mind, and there was a look of anticipation in his heart. meaning.

Deciphering Japanese ciphertext is a scene that was only seen in TV dramas in the past. Yu Hua has only seen it in a few dramas, but he has never been in serious contact with it.

However, there is one common sense that can be affirmed, that is, the fact that a secret agent and a spy can decipher the ciphertext in the drama TV series is completely unrealistic.

Deciphering the code requires extremely strong logical abstract thinking and mathematical thinking, as well as systematic knowledge, and ordinary people are simply unable to do it.

Agents and spies are indeed strong, but their intelligence is not that high.

There is an equal sign between a codebreaker and a mathematician.

Yu Hua was looking forward to this unexpected job. He wanted to do it well and help Master Hua Luogeng to decipher the Japanese ciphertext.

"There are still about 2 hours left in the state of efficient study today. Continue to study." After thinking about it, Yu Hua shifted his attention and turned his attention to "Theory of Real Variable Functions" on the table. There are still about two hours left in the efficient study time today. Don't waste it, turn the page again with your right hand, and sink into learning again.

Studying career, sailing against the current, if you don't advance, you will retreat.

Nowadays, the daily efficient study time has increased from 8 hours to 8 hours and 20 minutes, with an average of about 1 minute a day.

24 hours a day, you can fish at other times, and look at calculus to relax your mind and body, but the extremely precious and efficient learning time every day must not be wasted.

It's a crime to waste a second.

From a personal point of view, the young Yu Hua has a lot of time, and there are still decades to enjoy in the future.

But from the perspective of a scientist, Yu Hua's remaining time is extremely scarce and limited.

He is destined to stand on the top of science in the future, and he has the mission to lead the entire China forward, and he cannot afford to waste any time.

Time passed quietly.

Two hours later, with a familiar feeling of dizziness coming from his head, Yu Hua had to end today's study, quickly interrupt his thinking, empty his mind, and let him rest and relax.

After today's self-study, Yu Hua finally has a preliminary understanding and understanding of the integrability of functions, and he is one step closer to perfecting the construction of a thinking finite element analysis system.

Sitting on a chair to rest for a while, Yu Hua got up and opened the door, washing his hands with ease.

The night is deep.

Winter is coming to an end, and spring, a symbol of hope, is not far away.

"Good night, Yu Hua, tomorrow will be better."

After brushing his teeth, washing his face, and tidying up his personal hygiene, Yu Hua returned to the second bedroom, lay on the bed, looked at the snowflakes slowly falling outside the window, whispered softly, and closed his eyes.

Tomorrow will definitely be better.

……

The next day.

The sky is slightly bright.

Tsinghua West Courtyard, Room 28, Study.

"Cryptography is the technical science that studies the preparation and deciphering of passwords. It is divided into two categories. The study of the changes in the preparation of passwords is called coding when applied to encrypted communication. The history of writing is almost equal to writing, or in other words, from the day the writing was born, the password was born, and with the continuous use of the password, it eventually evolved into a discipline."

As usual, Hua Luogeng's voice echoed in the study. Today's first class is no longer esoteric and obscure calculus, but a brand-new mathematics course - cryptography.

Yu Hua sat quietly on the seat and listened carefully.

Hua Luogeng's lecture habits like to start from the beginning, from the development of cryptography, and then talk about the basic components of cryptography, such as cryptographic terminology, keys, plaintext, ciphertext, encryption, decryption, cryptographic algorithms and so on.

Passwords have confidentiality, authentication, content integrity and non-repudiation,
Confidentiality means that the password sender and the designated recipient can understand the content of the transmitted password. Authentication means that both the sender and the recipient can determine each other's identity, and a third party cannot pretend to be either party's identity. Content integrity is the responsibility of both parties. Confirm that the content of the transmission password information has not changed during the transmission process. The last point is non-repudiation. If the receiver obtains the sender's information, it must also confirm and confirm that the information is indeed from the sender. The sender cannot deny itself after sending the information. Information has been sent.

An hour later, the basic structure and situation of cryptography have been explained. Hua Luogeng saw Yu Hua's thoughtful appearance and simply asked a few questions. After Yu Hua's answers flowed, he talked about the development of cryptography in the current era.

"Currently, the development of cryptography is diverse. Germany is the strongest, using a cryptography called Enigma, followed by the United Kingdom and the Soviet Union, followed by my country and France, the United States is the second, and Japan should rank the second echelon. Germany got the prototype of the Enigma machine, but I don’t know if it is true, and now the Japanese code system we want to crack has been confirmed as a red secret by the Secret Service of the Blue Shirts.”

"Hong Mi..." Yu Hua chewed on this special word carefully.

"Yes, the red secret is upgraded from the green secret system. I don't know the details, but the red secret system is composed of language codes and replacement codes. The language code is Hiroshima dialect, the replacement code is Hill cipher, and the symmetric encryption mechanism , we are now conducting a ciphertext-only attack, and we need to use the frequency analysis attack method." Hua Luogeng explained with a serious face.

Ciphertext-only attack is one of the four attack modes in cryptography, and it is very difficult. To attack when only the known encrypted text is known, to try to decipher it, it is necessary to obtain the original plaintext.

The original plaintext, Hua Luogeng is naturally not lacking.

Yu Hua was thoughtful and nodded.

"Next, let's talk about the Hill cipher mechanism and the frequency analysis attack method. The Hill cipher is essentially a substitution cipher and adopts the principle of basic matrix theory..."

(End of this chapter)