In the middle of the night, the north of the inner city of the capital is sunny, and the lights are bright.

In the middle of the night, the yamen of the military department in the thousand-step corridor in the south of the inner city of the capital is brightly lit.

However, in the Yamen of the Ministry of War in the south, when he learned who was fighting at night on the side of the Shuntian Mansion in the north, Lu Juan, the secretary of the Ministry of War, was unprecedentedly unable to hold his breath and dropped the pen in his hand.

Then, after following him for more than ten years, seeing that Lu Juan had been promoted all the way from Langzhong to Shangshu, a confidant of Shangshu, Niu Tou persuaded him to say two words, but he was kicked out of the door, and the others did not dare to speak.

"He is a big head, and all cats and dogs can be invited to his Shuntian Mansion to help, but my military department yamen is clean and clean, and outsiders are not allowed to trespass!" Speaking these righteous and strict words, Lu Shangshu was furious in his heart.

was pointed out by Zhang Shou on the Zhigong Building before, and he didn't have no intention of sneaking his son Lu Sanlang over to decrypt it, but in such an important place as the Yamen of the Ministry of War, even if he is a scholar, he can't bring his son in casually! The result is good, it was his hesitation, and he never ordered his family to ground Lu Sanlang, but he was actually preempted by Wang Datou!

That unfilial son is really going to help Wang Datou!

He took a deep breath and said in a cold but stern tone, "Dr. Zhang has already identified the joints of those secret letters, and all the officials of the military department who are best at numbers and calculations have also gathered here. If it is solved before dawn, then everyone can atone for their crimes, if it can't be calculated, I will certainly ask the emperor for the guilt, and everyone of you has had it! This time, the military department is embarrassed and embarrassed! ”

The Yamen of the Ministry of War needs to crack thirteen secret letters at one time, but there is a big head of the palace Yin Wang who has a very high level of arithmetic in the Shuntian Mansion, so Zhang Shou and three students need to solve only one secret letter.

However, it was this letter, Qi Liang and Lu Sanlang, who had arrived one step earlier, turned it upside down and read it many times, pondering and pondering, but they were confused.

After Zhang Shou took over, he first examined the twelve letters that he claimed to have unraveled before, and finally went to look at the last letter that had not yet been unopened, and then pondered.

Probably because he was afraid that the secret letter would have to be examined or something, so as not to arouse suspicion, the contents of the twelve letters were all plain family letters. These ciphers, relying on whether there are horizontal lines between words to represent one and zero, and then separating them with punctuation marks, so binary numbers are introduced, and then combined with thousand-character text as a codebook, so that they can be easily unraveled.

And the last letter, a simple single piece of paper, dozens of words, but it turned out to be a completely incompatible, not a sentence at all, the writing is like a child's graffiti, and at the end there is a line of handwriting notes, the Tao is a child according to the words in the thousand-word text, practicing the pen randomly, although it is a little childish, but it is interesting to look at, so send it to the husband in the army to take a look.

Seeing these three words, Zhang Shou suddenly smiled slightly, thinking that this was probably another letter that used a thousand-character text as a code book, but the coding method was different from the previous twelve. Although a lot of disorganized words are used, if you follow the seemingly complicated but actually simple coding method of the first twelve letters, this secret letter is not so complicated in theory.

After all, even if it is relatively simple, there has been a big mistake in the exchange of secret messages, and the receiver will actually miscalculate the day......

This is probably the saddest event in the world, and it is no wonder that both the sender and the receiver committed suicide.

If encryption is simple, shifting the password is the most likely.

In other words, the original word is replaced with the word after a certain interval. And according to the logic of a simple password, there must be some obvious pattern to this interval. Directly replace each word with the word after the same interval, which is the most convenient, but also the easiest to crack, so the formula for shifting may as well be set to the simplest y=ax+b, and then the more complicated......

No matter how complicated it is, it is a more complex equation twice, but since the displacement distance must be an integer, and this x is definitely an integer, so it is actually difficult to go anywhere, so let's start with a simple calculation.

According to the law of simple passwords, the first word on MeSign is the word with the interval a+b on the basis of the corresponding number of the original word, the second word is the word with an interval of 2a+b on the basis of the corresponding number of the original word, and the third word is 3a+b......

Because there are only a few dozen words on the letter, the number of words is not much, but whenever it is shifted, the factor of circulation must also be taken into account, after all, the corresponding number of the thousand-character text is only one thousand, and from the ninety-hundredth word to the two or three hundred, it will return to the beginning of the thousand-character text.

Now he only needs to check the first four numbers, which means that the strength of the calculation is still within the acceptable range.

Zhang Shou thought about it while writing and drawing on the paper casually, but he didn't notice that the big head of the Shuntian Mansion Yin Wang was already standing quietly behind him. Without even noticing how much time it took, he deduced the simple cryptographic equation y=2x+3.

But when he counted the first four words of the original text backwards, he was really speechless...... Because I am still a Confucian scholar!

It seems that Confucius University is really the unluckiest person this time......

x = 1, 2, 3 representing the shift variable......

y=5,7,9...... representing the displacement result In other words, subtract 5, 7, and 9 from these words on the MeSign respectively, and then find the words in the corresponding position.

According to the clear numbers solved, Zhang Shou checked his memory against the corresponding number table of the thousand-character text that Wang Fu Yin personally ordered someone to copy, and then wrote a line of dozens of words on the paper.

On the day when the Confucius scholar passed the camp near the sea, he ordered the lord to send Du Heng to trap the rebels.

"Arrogance!"

Zhang Shou just wrote out all the words, only to listen to an annoyed shout behind him, and turned his head to see Yin Wang Jie of Shuntianfu behind him angrily, he saw Lu Sanlang, who was counting on a sad face, jumped up and rushed over, he stretched out his hand to stop Lu Sanlang, picked up the paper with one hand, and then said to Wang Jie: "Now it is true that the words have been concatenated into a sentence, but Wang Dayin doesn't feel strange?" ”

After the anger, Wang Jie immediately calmed down. He took the piece of paper from Zhang Shou's hand, and carefully studied it for a while before he said in a deep voice: "Could it be that the person who wrote the letter is clearly a traitor, but he claims to be a rebel?" ”

"This is one of them, and I also think that if it is a real rebel, maybe it will call itself a rebel army instead."

Wang Jie couldn't help frowning slightly: "Oh, you mean, there is a second?" ”

"It's just a feeling for me." Zhang Shou smiled slightly, and said casually, "The twelve letters are all written in one code, but there are more letters written in another code, and I am deliberately afraid that people will not be able to solve it, so I added a sentence, which is a thousand-character text copied by children." Can you imagine which child will copy a word in the east and a word in the west when copying a thousand-word text, but not a whole sentence? ”

Lu Sanlang, who sneakily came over, immediately realized: "That's right, that's right, it's like this, it's like telling others that there is something wrong with this letter!" ”

Qi Liang and Deng Xiaodao glanced at each other, and Qi Liang also said thoughtfully: "I also think that the words on the letter that look like children's graffiti are a bit deliberate, as if adults imitate children's handwriting." ”

Deng Xiaodao suddenly had an idea: "Could it be that the person who wrote this letter didn't understand the mystery of the twelve letters, but knew that the reference of the secret letter was a thousand-character text, so he racked his brains to encrypt it in a different way and wrote such a letter?" ”

Being reminded by everyone's words, Wang Jie narrowed his eyes slightly, and his heart was filled with emotion: "If I just play this letter that you have unraveled, Dr. Zhang, Du Heng, the master of the Linhai camp, will be regarded as a traitor to the mastermind." But these suspicions alone are not enough to clear his suspicions. ”

"But it's not enough to confirm his suspicions." Zhang Shou finally couldn't help yawning, and then said lazily, "Perhaps, the so-called people who committed suicide on both sides are actually just ghosts for the dead." Perhaps, someone wants to pull down the main general who is in the way and replace him himself, maybe...... Anything is possible anyway. But in my opinion, the biggest doubt is the sudden change in MeSign encoding. ”

"This letter that Wang Dayin didn't solve before is a letter ranked among the dates, and it makes no sense that the letters exchanged later have not been changed to the end, and the original encryption method is still used. In short, this is my view from the perspective of arithmetic, and the merits need to be judged by yourself, Wang Dayin. ”

"Good, good. I finally didn't cook those two guys for Zhao Guogong's Mansion in vain, otherwise Mrs. Tai might not agree to let you go. ”

A smile appeared on Wang Jie's stern face, and then he said lightly, "Dr. Zhang has worked hard tonight, but the night is too dark, I have wronged you to stay with them in my Shuntian Mansion, I have already ordered someone to clean the guest room, and hot water for supper and so on are also being prepared." Please don't misunderstand that I put you under house arrest, the stakes are high, and I will not forget your merits when I will make the joint clear tomorrow! ”