"Whether this is training and learning, or fighting with the enemy, it makes my heart beat faster." Qian Liang had a sad face, this was obviously not his area of expertise.

Seeing Qian Liang like this, Fang Chunlei wanted to tease him, and deliberately said: "This is definitely not the case with your assessment, you are careful that one day when you are outside, you are covered with a sack and taught a lesson." ”

"No......" Qian Liang said no, but he felt that what Fang Chunlei said made sense.

His ability is fighting, will he really encounter this kind of sneak attack?

In the next few days, Qian Liang walked on the road, always cautious, and turned his head from time to time to see if someone really wanted to cover his head with a sack.

Fang Chunlei saw it in his eyes, and he couldn't smile in his heart, Qian Liang really took it seriously.

But these days, there is a lot of pressure to study, the course schedule is very full, and everyone's life is full and busy.

And today, a new teacher came over to teach everyone new knowledge, and when class was in class, Fang Chunlei and others came over early.

The person who came was in his fifties, with a tall posture and a neat military uniform.

"Hello students, let me introduce myself, I am Wu Yongzhi from the Security Department. Originally, I didn't come to give a lecture to you, but the people on the radio station were so busy that I haven't had time until now, so I'll give you a lecture first. Wu Yongzhi said approachablely.

"Teacher Wu, will you tell us about the radio?" Deng Ruonan asked.

Wu Yongzhi smiled and waved his hand and said: "I don't dare to overstep the knowledge of the radio, I will tell you about secret writing." ”

"Cipher?" Many students cheered up.

"Which student can answer the question of what is the function of ciphering?" Wu Yongzhi asked.

Deng Ruonan was very active today, and took the initiative to stand up and said: "It is the same reason to encrypt with telegram, even if someone intercepts the telegram message you send, or intercepts the message you transmit, but it is incomprehensible. ”

"That's a good answer, that's what cipherwriting does, and of course, being more detailed can also help you avoid search."

Wu Yongzhi went on to explain a lot of precautions for cryptography, uses, and so on.

Immediately afterwards, Wu Yongzhi asked: "After talking so much, which student can explain how to make invisible ink?" ”

Qin Fanghao was the first to stand up this time and said: "The most accessible and easiest way is to use orange juice, lemon juice, onion juice or milk, directly dip it and write it on paper, and after drying, it is not easy to notice." ”

"To see this invisible information, you just have to bake it on a light bulb or iron and you can see it."

"How?" Wu Yongzhi continued to ask.

"In the case of lemon juice, it's because the paper absorbs acidic liquids and turns brown faster than the rest of the body when heated." Qin Fanghao replied very calmly.

"This classmate answered very well, please take a seat, is there anything else?"

"Teacher, it's okay to use vinegar, purple cabbage juice can make the text show."

"Teacher, copper sulfate, iron sulfate, and ammonia are also fine."

Everyone gossiped and expressed their opinions, Wu Yongzhi did not feel that the class was chaotic, but liked the feeling that everyone was involved.

"What the students said is very true, but one thing to remember is that you must use an ordinary pen and fill the paper with words, otherwise the blank letter will only look more suspicious." Wu Yongzhi's words made everyone laugh.

In addition to invisible ink, Wu Yongzhi also explained a lot of secret writing methods, such as hiding the head and hiding the tail, but it is much more complicated than this.

"Of course, you can write more cleverly, this is to improvise, not to set the pattern, otherwise the enemy will be easy to find."

"For example, an Italian scientist, Giovanni Porta......"

"Teacher, I know this." Deng Ruonan really knows a lot about this aspect.

"Then tell us about it." Wu Yongzhi did not feel that Deng Ruonan was impolite, but appreciated such a learning attitude.

Deng Ruonan had already given everyone many extra lessons, so naturally he would not be stage frightened, so he stood up and said: "This scientist used a little alum and vinegar mixed together to make ink, but he used ink to write on egg shells. ”

"The ink solution passes through the micropores in the eggshell and penetrates into the egg, leaving a mark on the surface of the egg white, and the information can be obtained by peeling off the eggshell."

"What do you think of this approach?" Wu Yongzhi asked the person sitting again.

Qian Liang said: "This method is good, hidden in the egg, no one can think of it, not even the paper." ”

"Wrong, not good at all." Wu Yongzhi's words made Qian Liang incomprehensible.

"This method, when I first used it, was very good and unexpected. But this method has been used many times in previous wars, and everyone has already taken precautions. ”

"Now when you see eggs, especially hard-boiled eggs, you must open them to find out, do you think this method is okay now?"

Only then did Qian Liang react, and there were more people who used good methods, and it became a bad street method.

"Teacher, wouldn't it be better if we encrypted the information when we used invisible ink to write information?" Qin Fanghao asked.

Without invisible ink, it is directly encrypted, and the encryption method will be chosen. Then when using invisible ink, the same encryption method is used, which is double insurance.

Even if the enemy discovers the contents of the invisible ink, the enemy does not know its true purpose.

"Be cautious, double insurance is good, the most important thing is that you should take advantage of the environment at the time, the surrounding objects, and play a surprise secret writing and transmission, so that it is the safest." Wu Yongzhi said earnestly.

In this class, everyone was very interesting and very serious about learning.

Fang Chunlei didn't answer a single question, but he gained a lot of knowledge.

There is only one such class, and more than one class will not work.

At the end of class, Wu Yongzhi said goodbye to the students, and everyone was a little reluctant.

"Minister Wu." Seeing Wu Yongzhi come out, Lin Shanyue greeted him.

"No need to send it, this phase of students in Qilipu is good, cultivate it well." Wu Yongzhi said.

"Hard work Minister Wu."

Minister Wu?

Everyone in the classroom didn't hear it, but Fang Chunlei did.

Wu Yongzhi said that he was a member of the Ministry of Security, who would have thought that he was actually the minister of the Ministry of Security.

However, Wu Yongzhi was reluctant to say it, in order to shorten the distance with the students and facilitate teaching, he heard it now, and pretended not to hear it.

"Leizi, there is so much knowledge in this secret writing, you have to be careful when you pass on information in the future." The more Qian Liang learned about ciphering, the more confident he became, but the more careful he became.

Because the enemy's search for intelligence will also focus on the aspect of secret writing, and the victory or defeat will be in a moment.

"It seems that Mr. Wu's class today is not in vain, and the professor of secret writing is only one aspect, and it is more important to maintain awe." Qin Fang got up and planned to leave.

Qian Liang followed behind him and said, "It seems that you are very experienced, do you write too many unsightly things?" ”

"You'd better be careful that someone sneaks up on you, Lei Zi and I won't show you your back today."

"Don't, help me look at it."

Out of the classroom, Qian Liang immediately looked around left and right, cautious.

Fang Chunlei followed behind, holding back his laughter really hard.