my scientific age

Chapter 114 Four letters!

Yu Hua took the black document bag handed over by Hua Luogeng, opened the seal on the surface, and took out the original Japanese plaintext information contained in it. These documents belonged to the latest plaintext correspondence of the Japanese foreign affairs department and the garrison army, and were all obtained by the Blue Shirts Agency.

Pick up the first page at will, and the contents recorded on it are all English letters.

The original Japanese plaintext is not Japanese characters, but English alphabet structure. The Hill cipher is composed of 26 base encryption matrix. Due to too many Chinese characters and Japanese characters, it is not suitable for the Hill cipher. The Japanese follow the international mainstream practice and apply English The structure of the Hill cipher algorithm in which letters and numbers are interrelated does not specifically compile a set of 26-base Japanese characters.

From the surface of the first plain text, the entire string of English letters is arranged without any regularity. It is blunt and abstract, giving people a feeling similar to random scribbles. Yu Hua saw it at first glance and immediately thought of countless English words. Taobao is like this.

After reading the first original plaintext data, Yu Hua carefully wrote down all the contents, his face was natural, and he was not in a hurry. He then turned to the second one and continued to read it. According to the laws and habits of human linguistics, even if there are no rules, As long as the things of speech are related to people, then there will be rules.

The first rule of cryptography: people will always make fatal mistakes - habits.

Seeing this, Hua Luogeng did not urge him, but waited quietly with a smile on his face.

After about ten minutes.

Yu Hua put down the latest original plaintext document. He had already read about one-third of the original plaintext document. He closed his eyes. A large amount of Japanese original plaintext document had already accumulated in his mind. Strings of English characters were suspended in mid-air, densely packed. The number reached about tens of thousands. In the next second, the brain like a computer was running at full force. Yu Hua first used the most effective and direct frequency analysis attack method to extract the frequency of letters and letter combinations.

After a few seconds, a set of ciphertext combinations appeared - A, ABB, ABBF, ATH.

The ciphertext letters and letter combinations in this group of ciphertext combinations have the highest frequency of occurrence, reaching 200 times, 89 times, 76 times, and 23 times respectively. After obtaining the first set of ciphertext combinations, Yu Hua continued to use the frequency analysis attack method, constantly A set of ciphertext combinations are obtained.

Seeing Yu Hua close his eyes, Hua Luogeng knew that he, a student with extremely terrifying mental arithmetic ability, had already started to analyze and decipher the frequency, and there was a look of anticipation in his eyes.

He, this student, did not say anything else, saving manuscript paper is undoubtedly the first in the country.

The skill of mental arithmetic, even Hua Luogeng, who is famous for his mental arithmetic at Cambridge University, is not enough in front of Yu Hua.

In his mind, a group of ciphertext combinations kept appearing, until the frequency analysis was completed, Yu Hua got a total of 430 eight ciphertext combinations, and then reversed analysis based on the encryption algorithm principle of the Hill cipher, and through the thinking of calculus, established An approximate matrix, which continuously reverse-analyzes 430 eight sets of ciphertext combinations.

The entire parsing process was extremely labor-intensive, and Yu Hua had no idea of ​​cheating or any way of cheating. When the password was deciphered to the parsing stage, he could only hit hard, and there was no other way.

Historically, in order to crack the Enigma machine of the German army, the United Kingdom gathered the strength of the whole country, gathered many mathematicians and related personnel, and assembled a code-breaking team of more than 1 people to carry out code-breaking work 24 hours a day, requiring resources Give resources, give what you want, and finally, under the leadership of Turing, find the Achilles heel of the German army, and only then can you crack the Enigma machine, which is said to be impossible to crack.

But in the parsing link of cracking the password, there is no so-called shortcut. Either the numbers are calculated, or the information content is not obtained.

Fortunately, Yu Hua has a brain comparable to a computer, and the computing power is comparable to the eighth-generation Core I5 ​​CPU.

An hour later.

"Huh..." Yu Hua suddenly let out a sigh of turbidity, his face turned pale, and his head was dizzy, as if he had been hit by a heavy hammer on the back of the head.

"Xiao Hua, are you alright?" Hua Luogeng was also a little startled when he saw Yu Hua's appearance. Seeing this state for the first time, he quickly asked.

Yu Hua shook his head again and again, feeling a little disgusted, took a deep breath, cheered up, and said quickly: "Professor, I'm fine, this is the alphabetical order of the ciphertext I solved and deciphered. Currently, I only find the numbers corresponding to 4 letters, A corresponds to =9, B corresponds to =2, F=3, H=1."

"ABFH, very good, I have deciphered 6 letters during this time, and it did not repeat the four letters you deciphered, plus the 4 new letters you deciphered, we have mastered ten letters in total, and now we can establish an approximation The matrix mathematical model, if you put ten letters in it...you can decipher some of the original plaintext words."

Hua Luogeng was pleasantly surprised when he heard the combination of four letters and numbers given by Yu Hua. He picked up the pencil in his right hand and wrote it down immediately, and then performed mental arithmetic in his mind, and quickly gave the calculation results. There was a hint of excitement in his words.

Surprise.

A real surprise.

Hua Luogeng couldn’t help but be surprised. There was no way. For nearly a month, Hua Luogeng had been worrying and worrying about deciphering Japanese ciphertext every day. letters.

Today, after Yu Hua first came into contact with the work of deciphering Japanese ciphertext, he immediately gave him a big surprise.

Don't underestimate these four letters. The four letters deciphered by Yu Hua are all new letters, and they do not overlap with the six letters deciphered by Hua Luogeng.

In other words, with the number of deciphered letters reaching ten, now they have initially mastered the ability to decipher some of the original plaintext words, presumably the previous situation is simply a breakthrough progress.

Hearing this, Yu Hua smiled reluctantly, but did not speak, his face became paler, and his dizziness became stronger and stronger.

"Xiaohua, if you crack 2-4 letters every day, we only need about 8-4 days to complete the first goal."

Hua Luogeng raised his head, resisted the excitement in his heart, and said, "In the near future, we may be able to decipher the ciphertext simultaneously in a single time."

In Yu Hua, Hua Luogeng saw the hope of simultaneous deciphering, which is the supreme pursuit in the field of code deciphering.

What is simultaneous deciphering?

Not only the sender sends the communication message to the receiver, the eavesdropper as a third party and the receiver obtain and translate the information content sent by the other party at the same time.

In layman's terms, the Japanese garrison sent a mobilization order to a certain wing, and this order was obtained and translated by both itself and the wing, and the situation would evolve to the fact that the wing did not know that the ciphertext had been leaked. Immediately mobilize the troops to set off, and the one who has obtained the communication order can choose to escape, or choose to ambush on the road, or even attack the wing station.

What is this called?
One-way information transparency.

What is the advantage in me, the party with one-way information transparency, this is called the advantage in me!

Such a situation is undoubtedly great news for the country and the military.

"Teacher, professor, student..." Yu Hua opened his mouth and wanted to speak, but his voice was as weak as a mosquito. After two seconds, he had not finished speaking, accompanied by a strong sense of dizziness, he couldn't hold it any longer. , the whole person suddenly blacked out, lost consciousness, and immediately fell to the table.

"Bang!" Immediately afterwards, Yu Hua's head made a close contact with the table, and there was a loud and short crashing sound.

"Xiaohua!"

……

"Old irons, open the red, open the red, watch me eat a cake, the big guy will reward you and walk away."

"Thank you for the gift from Big Brother Bang, thank you."

"Yo, return the skin, it's just the skin-turning water."

"In the new season, rush, rush, and chop off the first if you don't go to the national service."

Yu Hua looked around blankly, and the voices of various live broadcast rooms kept coming from his ears. This is his computer, surrounded by a bedroom with simple furnishings, a computer desk, full of stickers of various military equipment, and A bookcase, and the scene in front of him all shows that this is his home.

what happened?

I'm home?
(End of this chapter)