Chapter 192 Code Deciphering

"Luo, let's go, drink with me?"

"Mr. Yardley, I don't have time to drink with you. I have a lot of documents that need to be read and sorted out." Luo Yao worked hard.

Since Dai Yunong has given him the task of setting up a code deciphering center, he must do it seriously. Moreover, code deciphering is very important in intelligence work.

If you can master the enemy's communication secrets, then all the enemy's deployments are under your nose, which is much safer than sending intelligence agents to lurk inside the enemy to obtain intelligence.

Of course, this does not mean that it is not necessary to send latent agents to the enemy to obtain information, but it is also necessary. The information cannot be isolated evidence and must be verified by each other.

After all, encrypted communications can also be forged, and enemies can use this to commit tactical or even strategic fraud.

"Luo, you actually understand this?" Yardley lowered his head and glanced over, and was shocked to see that Luo Yao was actually classifying and organizing the information he brought about code deciphering.

He dug these things out from the bottom of the box at home. In the United States, these information are considered confidential. However, Americans don't seem to pay attention to these things. He can only bring them to China to see if he can find them and put them to use. Opportunity.

Some of the information is very scattered. He was a very casual person in life. Although he collected it, he did not organize it accordingly. Even his novels were dictated by himself and others helped him polish and organize them.

Without the royalties from the publication of the novel, he would have lived an extremely poor and miserable life in the United States during these years.

Otherwise, he wouldn't be attracted by the high remuneration.

To say that there are many noble sentiments, in fact, it is all nonsense. He came here just for money. Without money, how could he live a life of luxury and luxury?

Without wine and women, what fun would there be in life?

"Some are good, some are not." Luo Yao nodded.

"Oh, really?" Yardley didn't really believe it. These things of his were usually kept at home and no one looked at them. They were thrown under the bed and were a bit moldy. Even wiping his butt and buttocks were hard. If he hadn't come to China this time, he would have almost forgotten that he still had these things in his hands.

Many of them are basic. Of course, he considered that China might need these, so he brought them over.

Because he needs to use these to train some personnel in this field, and he should start from the most basic things. Encryption code deciphering cannot be completed by one person. It also requires the division of labor and cooperation of many people, and a lot of work must be done. Otherwise, one person simply cannot complete such a large workload.

This is a race against time. By the time you successfully decipher it, the battle may be over, so what’s the point?

Without enough people, it will definitely not work.

What Yardley wants to do in China is to help China cultivate a group of code-breaking talents. Of course, it is not that China does not have such talents, but there is no system, or there is no professional training. The model of a master leading a disciple.

Moreover, codebreaking is a special industry that cannot be entered by just anyone and requires strict assessment and political review.

In fact, domestic talents of this type are very scarce, and although the national government has made some progress in deciphering Japanese secret codes, the progress is very slow due to technical and talent constraints, and Japan must be ahead of them in this regard. In front.

Intelligence shows that Japan has achieved great success in deciphering China's secret code, and has even basically mastered the rules of some of China's secret communication codes.

In these battles, China suffered a huge loss. Before the battle started, its own deployment was known to the enemy. How could we fight this battle?

There are also some frontline generals who do not have a strong sense of confidentiality. When fighting, they actually use clear codes. Doesn't this mean they directly tell the enemy how they fight?

How can we go undefeated in this battle?

"Luo, can I ask you a few questions?" Yardley became interested in this matter.

"certainly."

"There was an encrypted communication method in ancient Rome, the 'Spartan Rod'. Do you know what it is, and can you tell me its encryption principle?"

"Mr. Yardley, you are wrong. The 'Spartan stick' is an encrypted communication method used by the ancient Greek army. The method of use is to wrap a long ribbon-like parchment around a wooden stick, and then write on it. , after untying the parchment, there is a string of chaotic characters on it. Only by wrapping it again in the same way on a stick of the same thickness can the contents of the paper be read." Luo Yao smiled slightly.

Yardley nodded. He actually deliberately referred to ancient Greece as ancient Rome, just to test whether Luo Yao could hear it.

I didn't expect that the other party was so attentive and heard it right away.

"In fact, this 'Spartan Stick' uses a typical 'transposition method' to encrypt communication content. As long as you know the method, it is very easy to crack." Luo Yao continued.

Yardley nodded. As long as you have learned the common sense of code deciphering, it is not difficult to know this knowledge point. However, considering that Luo Yao is a Chinese, it is still very powerful to know the encrypted communication method of the ancient Greeks. , even in the intelligence community, it is considered good if two or three out of ten know about it.

"Okay, next question, a text communication encryption method invented by a consul in ancient Rome more than 2,000 years ago. We call it Caesar cipher. Luo, do you know how this Caesar cipher is encrypted? " Yardley continued to ask.

"Haha, the Caesar encryption method is actually the prototype of our cipher code encryption today. It uses 'single letter replacement' encryption. The principle is very simple and easy to crack..." Luo Yao talked eloquently.

Yardley was very surprised. Although these were just two simple questions, not many people knew about them. Even those who studied secret telecommunications may not know.

Because knowing this is the basis of password deciphering, if you don’t understand the principle, how to crack the password.

In essence, the current cryptographic communication encryption methods are all derived from "alphabet substitution", but what has changed is the substitution rules.

Once you master the rules, you crack the code.

It's easy to say, but difficult to do.

"Luo, if I write a paragraph and you encrypt it using single-letter substitution, can you decipher it?" Yardley became more and more interested in Luo Yao.

"I can give it a try." Luo Yao nodded. He could write his own codebook and crack a small single-letter substitution encryption. That was no longer childish.

The so-called single-alphabet encryption is not without rules. If you create a single-alphabet encryption table just to replace a sentence, it can actually be deciphered, but it will take a little longer.

Cracking single-letter encryption requires a certain reference text, and then analyzing the reference text. To put it simply, it is the use of probability in mathematics.

For example, in an article written in English, the probability of 26 letters appearing in an article can be replaced by letters with the same probability in the encrypted sentence.

Of course, the ciphertext of one sentence is too short. It would be easier if the text were longer, because if you calculate the probability, the more words, the more accurate it will be.

But as long as you try them one by one, it is only a matter of time before you can crack the ciphertext.

The probability of 26 English letters appearing in an article has been studied for a long time. There is no need to count this anymore. If it is "multi-alphabet replacement encryption", it will be much more difficult. Even the longer the article, the more difficult it will be. Crack.

Yardley randomly compiled a replacement alphabet, then used this alphabet to write a dialogue, then encrypted it and gave it to Luo Yao.

Luo Yao took a look and saw that this conversation was not long.

Four sentences, the third sentence is a little long, and the others are very short.

But literally, they are just meaningless letters that cannot form words at all and are completely incomprehensible, but there must be content in them.

Because it was a "single-alphabet replacement," Luo Yao first began to calculate the frequency of each letter in this ciphertext, and then counted them before replacing them.

The basic method of cracking replacement encryption can be called probability and statistics.

Of course, different texts and languages ​​also have their own characteristics, such as what are the most commonly used words in English, what is the most commonly used letter of an English word, etc.

The summary and application of these rules can achieve twice the result with half the effort in code deciphering.

As long as you master these, it is actually very simple to crack a single-letter encrypted ciphertext. As long as the IQ is not too low, it can be completed quickly.

What's more, Luo Yao has already done some research in this area. Although he is self-taught, he is not a bit better than those who have become a monk halfway.

It only took less than ten minutes!

The single-letter encrypted cipher text that Yardley wrote down at random was directly deciphered by Luo Yao, so fast that he found it incredible.

Luo Yao took a look and saw that this was not the code word he used to communicate with Yardley!

Of course, he didn't know it before deciphering it, and he couldn't tell it, because there was no space in the middle of the cipher text, so he couldn't guess it from the length of the sentence.

"Luo, you definitely have the talent to decipher secret codes!" Yardley excitedly gave Luo Yao a thumbs up.

"Mr. Yardley is so complimentary. Single-letter substitution deciphering is the basis of code deciphering. Anyone can do it after a certain amount of training. It's just that practice makes perfect." Luo Yao said with a humble smile.

"Luo, I think you can become my assistant in China!" Yardley said solemnly.

"assistant?"

"Yes, I need an assistant in China. You are not only proficient in English, but also know how to decipher secret codes. This will make our communication more convenient." Yardley said, "I will apply to the Chinese side."

"Mr. Yardley, didn't I tell you yesterday that I would be responsible for your life and work in China?" Luo Yaodao.

"Really? I forgot. Sorry, what did I do to you just now?"

"Discuss how to carry out work in China..."

"Really? I'm not here to drink with you?" Yardley said, slapping his forehead.

Luo Yao said very firmly: "Of course not. We just agreed yesterday that we will not drink during the day and during working hours."

Keep asking for monthly votes and recommendation votes!