pure white

Just like when I went from Chongqing to Changsha, Mr. Chi came to see me off. Now I return to Chongqing from Changsha, and Mr. Chi also comes to pick me up.

A windbreaker with a top hat, and a three-piece suit full of personable manners. After seeing me, Mr. Chi thoughtfully wanted to give me a hug in accordance with British customs. I took a step back and said with a smile: "Mister still treats me like a little girl ?”

Mr. Chi took out a handful of chocolates from his pocket: "This is how I treat you like a little girl."

I laughed, "I think we can try again, the little girl won't eat your sugar-coated cannonballs."

Mr. Chi laughed, and stretched out his hand after laughing: "You have indeed grown up. It seems that you have gained a lot from this trip to Changsha, but anyway, welcome back, Lu An."

I took his hand and separated in just two seconds.Mr. Chi's hands are also well-articulated, but they are a pair of scholar's hands, and calluses grow on the place where the pen is held.On the hands I'm used to holding, there is a thin layer of spear calluses on the tiger's mouth.

I followed Mr. Chi to the office, and my desk was moved directly to Mr. Chi's office for the convenience of discussion.

It is urgent to decipher the Japanese army's code, and I started working with Mr. Chi on the first day of reporting.

Before that, Mr. Chi actually had a clue, and I had been exposed to the Japanese army's codes on the front line in Changsha for a long time, and I had accumulated a lot of practical experience.We combined the previous results of the two of them for research, and finally we actually deciphered the numbers in the Japanese army's secret message.

At first, Mr. Chi discovered that the secret messages of the Japanese army consisted of English letters, numbers and Japanese characters after statistics. I also found this in Changsha, so I took out the notebook I made at that time to check it. I wrote the statistics at that time. Most of the results are " MY, HL, GI..." and so on.Mr. Chi followed my statistics and checked the calculations, and finally found that there were ten groups of such results.

"So it can be ruled out that the Caesar cipher is used for fence encryption?"

I was quick to speak and then realized something was wrong. I wanted to make amends but saw Mr. Chi laughing. He said empathetically, "Did you play password games with your comrades in Changsha?"

I shrugged and told the truth: "In my spare time, I taught Chen Jingyu to encrypt the combination of Caesar and the fence, so I was quick to speak."

In fact, it was just a small episode. Mr. Chi and I both made a cup of tea to relieve our slightly tired brain after several days of high-intensity work.

After resting for a while, Mr. Chi continued his theory: "I want to assume these ten groups as digital codes, and set the highest frequency "MY" as 1, and the lowest frequency "GI" as 9..."

It dawned on me: "You're saying that using the simplest frequency analysis to guess the starting point, relying on the language's dependence on letters to set up an alternative cipher, is like playing Scrabble, switching from 'Banbury Rims' to ' Desaibans', as long as the probability is calculated on a logarithmic scale, it can be solved according to the Bayesian method?"

He listened to my words and thought for a while, then praised: "Your understanding is correct, but why do you have to quote so many academic viewpoints to prove your own ideas?" He pointed to an open foreign book on the table. Half-closed to see its title, "Holmes: The Dancing Man".

I read this book when I was in the UK, and I had a deep impression of the code of the "dancing little man" in it, which is decoded by analyzing the frequency of letters.

I blushed and stammered for a moment, the explanation I gave earlier was indeed too long-winded.Mr. Chi didn't care, and said with a smile: "Lu An has graduated from Cambridge, and it's time to form his own theory."

I wrote down what he said, took my notebook and started to check the calculations.

Guessing the starting point by frequency analysis is the most basic job for a cracker. From the earliest times, the Caesar cipher is a cipher designed by Caesar based on the dependence of language letters. "Banbury Rims" is to punch holes in long sheets with pre-printed letters. When moving from left to right, observe these punched sheets, they will overlap each other, and the more overlapping small holes, Then it shows that the probability that the letters may match is 1:17, the greater the possibility.This greatly reduces our workload and shortens the likelihood that we need to calculate.

We made a two-alphabet to test the possibility in actual combat.

In the end, it was found that these numbers are likely to be the unit designation of the Japanese army, or the number of soldiers.

According to these, we have made more and more breakthroughs.We found that "West" means the United States, "North" means the Soviet Union, and "Southeast" means China. The secret messages of the Japanese army are hidden in the weather forecast. , it indicates that it is the ciphertext we need.

After getting the result, we are very happy.Mr. Chi treated guests to dinner, and we ate steak in the best western restaurant in Chongqing, which moved after the fall of Nanjing.

Mr. Fanmaike invited me to dance. There is a dance floor in the center of the western restaurant, and the white grand piano next to it is played by a player to dance music.

I put my hand in Mr. Chi's, and he led me to a ballroom dance.He said I danced very well.

I laughed and said, "I did this dance many times when I was in Cambridge."

"It should come to mind, your life in Cambridge must have been rich."

I laughed and said nothing, and it was one of my most cherished memories.

At the end of the dance music, Mr. Chi asked me if there was anyone I liked.

I answered him: "Yes."

"I can tell you laughed like a little girl when you danced with me. Do you remember him? Where is he? Would I have the honor of being your witness if I could?"

"In Changsha, she was the staff officer of the pre-tenth division. She taught me my dance steps in Cambridge." I raised my head and smiled: "After we win, if we get married, I will definitely invite you to come."

On December 30rd, [-], we intercepted a special classified telegram from the Ministry of Foreign Affairs of Japan to Nomura, the ambassador to the United States.

After Mr. Chi and I deciphered the generator, our hearts skipped a beat. We looked at each other solemnly, and Mr. Chi said, "This may be a secret message that can change the pattern of war."

Mr. Chi is right, this secret message is a harbinger of war between Japan and the United States.He submitted the plain text directly to the chairman of the committee, and four days later, the Japanese army attacked Pearl Harbor.

After reading the newspaper, my heart felt cold. We had already intercepted and deciphered the Japanese army's secret telegram, and even the time and place were clearly marked. Why didn't they pay attention?Is human life so worthless!

Mathematics is no match for politics.

The instructor was right.

On December [-], the Japanese army attacked Changsha for the third time.

I sent a telegram and got a reply from Chen Jingyu that everything was fine.At the end of the year, I met Wu Nianhe at Chen's house. Nianhe was alone, and he was talking with buds. I asked Nianguo to take his sister out to play. Uncle Chen told me that Wu Yingtang died for the country.

a bolt from the blue.

I asked why, and he said that Yingtang died in Changsha. Chen Jingyu managed to send back his family members and suicide note in the rear, and his body was sent to Wu's house. If you want to go, you can go and see it.

Only Nianhe is left in the family, and his wife was killed by devils in the flames of war.The body was just a handful of ashes, and the white-haired people from all over the Wu family sent the black-haired people.

Uncle Chen asked me: "You juniors, why are you so cruel!"

After I returned to Cambridge, I saw some reports at the time, saying that the Japanese offensive was more violent than the previous two times. The Tenth Army’s Pre-Tenth Division was originally stationed at the Yuelu Mountain position, but was later transferred to Changsha. The enemy forcefully crossed the Laodao River and Liuyang River. Finally, bypassing the east gate, the main force went straight to the position of the Tenth Division.With Changsha City behind them, there was nowhere to retreat, and the entire division could only do their best to fight to the death, leaving a will.After the war, the whole division lost more than 7000 people to more than 2000 people. Wu Yingtang was one of the 5000 people who died.

The first time I occupied the military line to call Chen Jingyu, I cried and told her that as long as you are willing to come back, your father will find a way to transfer you back.

Chen Jingyu laughed, the laughter choked out of her chest, soft and boneless, her voice was warm, she called my name softly, like the love words we used to whisper in my ear.

"A'an, we are about to win."

"You stay in Chongqing well, and when I come back, I'll take you back to Cambridge, okay?"

Wu Yingtang's will was hidden in Nianhe's body, and she secretly handed it to me when we were alone, as if she was treating the candy in her pocket with care: "Father said, I want me to give this to my godmother."

I rubbed her head, held back my tears and smiled: "Nianhe is so good, go and play with brother?"

Nian Guo came over, holding Nian He's hand like a little adult, coaxing her: "Nian and we go play in the garden, okay?"

I locked the door and sat down at the desk.

The letter reads: "From Lu An personally"

Inside is small letters written with a pen, the font is stable and powerful, with some mud stuck on it, he wrote it in the front trenches.

"A'an, I haven't called you like that for a long time. It's strange to say that when I was in Cambridge, I still treated you like a little sister. After returning to China, I found you have grown into a big girl. It doesn't matter if I call you An'an again. I can’t cry anymore. You have grown up in the war, and you have taken responsibility and concern. I am very happy. You have grown up in the war. Although many things are not what I want you to see, you still have the knowledge of mathematics in Cambridge. I am glad that you understand that patriotism is not a word or a profession, it is your actions and the tenacity in your heart. I know you still don't understand me, Jingyu, Xiaohuo, and like us What so many young people have given to this country, including our lives. I don't blame you, you are not wrong, your best memories are in the UK, but it is also our best memories. It's the same here. Our motherland has nothing to lose. All we can do is to dedicate everything to her in exchange for her rebirth. I told Chen Jingyu before that what we are doing now is to not Let Nianhe, Nianguo and their generation repeat our mistakes. Our generation must leave some light and peace to the next generation, right?

This battle is extraordinary, I can't tell you too much, but Changsha City is behind us, the people of Changsha are behind us, and your favorite wonton shop is also behind us, I have to guard her.

I don't know if I can survive, if not, I entrust Nianhe to you.Chen Jingyu said that as long as there is Nian Guo and you, there will be Nian He.I believe it.You have to raise your school well, let her study at Cambridge, let her play under the sky and on the lawn of King's College, let her go to the library to read, let her study the major she likes.If she likes to read the country, then marry him.

I am determined to stick to Changsha. If I die unfortunately, I will also die for my country. Don’t be sad, and don’t be sad when you want to reconcile. My flesh and blood will be turned into a towering mountain of China, and my blood will flow into the Yangtze River and the Yellow River.I, my brother, and my comrades will live with China forever.

Don't read, don't be sad.

Wu Yingtang

December of the 30th year of the Republic of China"

The author has something to say: All Japanese code-breaking methods come from Chi Buzhou and "The Biography of Alan Turing"

The decryption method in the middle is blindly written