I Can View Character Attributes Chapter 255: Steganography

"Yes, it's no use asking."

Xia Xu also realized this and felt helpless.

Things go round and round and seem to be back to square one.

Finding Pan Long's dad's blog was a boon, but the only clues now seem to be photos.

"Could it be some kind of steganography?"

After a moment of thinking again, He Qing suddenly made a suggestion.

Steganography, as the name implies, is the way to hide and write certain information, hiding certain information in another thing.

Different from encrypted communication and cryptography, steganography is not just about not letting a third party know the content of the communication, but to go further and hide the fact that it is "communicating" itself.

"Wait, let me verify."

Meng Bochao was reminded to download the picture on the blog page.

He first tried the easiest way to change the photos to txt text format or rar and other compressed file formats to see if this format conversion could be used to hide some content and files.

After he didn't get the harvest, he tried more complicated methods one after another, and everyone quietly waited for his results.

"It does seem possible that lsb steganography is used. The probability of 0 values ​​in the least significant bits of rgb values ​​is too high."

After a while, Meng Bochao spoke up in high spirits.

"What do you mean?"

Pan Long was confused by these convoluted professional terms, and he was most concerned about this matter and hurriedly asked.

“lsb is a form of steganography, short for least significant bit.

Usually a photo is composed of pixels, and the pixels are recorded with three values ​​of r, g, b and three channel colors of red, green and blue. It is equivalent to the three primary colors, and any color can be composed of rgb values.

And the rgb value is represented by numbers from 0 to 255. The numbers are stored in binary in the computer. The decimal system we commonly use is to add one to the number ten. Binary, as the name suggests, is two to one. Values ​​are recorded with regular 0s and 1s.

lsb steganography is to modify the least significant bit of the binary value, change the 0 of the least significant bit to 1, or change 1 to 0. After the binary value is changed, the rgb value will change, but it is only extremely small. It is almost impossible to tell the difference with the naked eye..."

This is great, a large piece of more convoluted concept science spit out from Meng Bochao's mouth, layer by layer, which can be called a Russian nesting doll.

"Stop, bully me for not understanding computers, right, just tell the conclusion."

Yang Bowen stopped Meng Bochao with a big head.

"Well, to put it simply, the probability of occurrence of the least significant bits 0 and 1 in the pixel data of a normal photo is close to the same, but the probability of occurrence of the 0 value in this photo greatly exceeds the standard, it is likely that someone Changed."

Meng Bochao stopped showing off angrily, and said simply: "This kind of change can't tell the difference with the naked eye, but the written information can be hidden by referring to specific rules, and these rules are also ready-made, and there are many common formulas in software development. Character encoding table, different numbers can represent different letters and even Chinese characters."

"So you can crack the hidden information inside?"

He Qing asked sharply.

"Theoretically this is the case. There are only those kinds of coding tables. You can find the rules by comparing them, but the problem is that I don't know which pixels are changed. I have tried it just now, not from the beginning to the end. Regular changes made by pixels."

Meng Bochao laughed awkwardly.

The current situation is that he knows that some text information is hidden in it, but he does not know that it is hidden information.

After all, pixel values ​​are also represented by numbers, and the result after comparing with the character encoding table is not necessarily the hidden information that is written.

To describe it simply, it is like a poem with a hidden head or a hidden tail. If you know that it is hidden, you can see it at a glance.

But if there is no pattern hidden in it, it will be difficult to see, unless you figure out the pattern or try to form words one by one.

"Isn't this a ready-made control group."

Xia Xu picked up the physical photo on the briefcase and threw it onto Meng Bochao's laptop keyboard.

Meng Bochao was probably a little overwhelmed, and he glanced at Xia Xu speechlessly: "This is not photo data, and shooting or scanning this photo will also produce light and dark differences, and the camera equipment will again cause random background noise, which is not at all. It is possible to get the same original digital picture."

"What if I could get the original digital photo?"

Xia Xu raised his brows with a playful look on his face.

"Then I ate my notebook."

Meng Bochao patted his big belly.

"Haha, yes, yes, I'll be a witness, how about another opening, or a bet?"

He Qing immediately booed.

Xia Xu smiled and said: "I don't mind, or I'll bet on your monthly salary. If you win, your salary will be doubled. If I win, your monthly salary will be deducted."

"Boss, I support you personally, but you put me on the opposite side so directly..."

He Qing looked sad, and then instantly turned into a smile that couldn't be concealed: "You can't blame me for not supporting you."

"Of course, not your fault, anyone else?"

Xia Xu looked at Yang Bowen and Pan Long playfully. As for Meng Bochao, he naturally participated by default.

"Hey, don't gamble, don't gamble, Lao Yang, I have a family, and I have to pay my salary, so I can't afford to gamble, but I still support and believe in you, boss."

Yang Bowen politely refused.

As the first existence to follow Xia Xu, he knows his boss's ability, and he knows that he is well-informed and never does anything unsure.

"I won't gamble..."

Pan Long also sneered and refused.

The reason for this is that, firstly, Xia Xu's image of being tall and dignified in the past two days is due to the fact that he is a little ashamed to talk about it - he has no money.

He's not an employee here, but he just inquired about it casually. The basic salary of Yang Bowen and these people starts at 20,000 if they don't work, how can he have so much money to bet.

"I, I believe in you too."

Although Tang Youxin did not participate, she also made a statement.

Well, it's so cute, as expected of my little white flower.

And Xia Xu naturally wouldn't let Xiao Baihua down, he reached out to pick up the photo on Meng Bochao's notebook again, and said with a smile, "I can't compare these professional skills with you, and restore this photo to its original digital form. I really can't do anything about the negatives."

This is obviously followed by a 'but'.

"However, have you ever thought that Pan Long's father left steganographic messages in the pictures on the blog for covert communication, to be precise, to leave messages for specific people. In this case, then There must be a way to decipher it."

Xia Xu's remarks really opened up the minds of several people who were stuck in a dead end of thinking, but soon they realized that the essence of the problem had not changed, Meng Bochao said directly: "But boss, I also know that there is a way to decipher it, But the question is how to decipher it? Where?"

"I said this just to tell you that this method of deciphering must exist, and it was left by Pan Long's father, to be precise, the person who left the steganographic information."

Xia Xu smiled and raised the photo in his hand: "As for the decoding method, isn't it here?"

"In here?"

Everyone is completely stunned.

Because the problem still hasn't changed, they just can't get started with this photo.

After seven or eight laps together, did it return to the origin? What about the Ouroboros?

Seeing this, Xia Xu could only helplessly continue to explain: "You can't just stare at this photo, this photo is actually just a reminder to let people know that this photo exists.

Actually, the key to decryption requires a different perspective, such as where did this photo come from? Surely you need a digital camera to shoot, right? Do you need to print for sure? "

"Yes."

Yang Bowen on the side had an epiphany, and couldn't help but be amazed: "The point is the source of the photo, you must have equipment to take this photo, and it's so clear after a long time, those old cameras can't take pictures, they must be using professional equipment from the past. shot."

"That's right."

Xia Xu nodded with a chuckle: "So there should be original digital negatives in the camera, and since Pan Long's dad must have left a deciphering method, the camera must still be there, and the original negatives in the camera must also be preserved. /

As for the place to keep it, it's also obvious. This photo that serves as a reminder is placed at Pan Long's house, so only Pan Long and his family are most likely to get it. The camera or backup digital negatives must be left with them. , or in the process of developing and printing this photo. "

"Fuck you, boss, you're amazing."

Everyone suddenly became enlightened, and immediately turned their eyes to Pan Long.

"I do have an old-fashioned digital camera at home, but I haven't used it. I didn't understand it when I was a kid. When it got older, it would have been out of power and would have eaten ashes at the bottom of the cabinet."

Pan Long understood what they meant, and his expression was also a little excited, and he said in memory.

"What are you waiting for, go back and get it."

Meng Bochao urged.

"I can't tell you are very kind, but don't forget, you can't bet on your bills, and I won't pay you two this month."

Xia Xu reminded with a smile.

Meng Bochao: "..."

"Boss, I was wrong, don't deduct my salary, I'm innocent, it was you who took the initiative to assign me to the enemy camp, I am in the enemy camp and my heart is Han~"

He Qing, who was reminded of this stubble, was about to cry without tears.

"Hahaha~IndoMTL.com~ deserves it."

Yang Bowen immediately gloated.

Watching you lose money is more refreshing than making my own money.

"Madam, please help me to say something nice~"

Compared to He Qing, Meng Bochao clearly realized who his savior was, and looked at Tang Youxin eagerly.

Unfortunately, Xiao Tang glanced to the side, pretending not to hear.

╭(╯^╰)╮hum, I told you not to believe him, and now you still want me to beg for mercy, think beautifully.

I'm also very stingy.