What is the difference between China Telecom’s quantum encryption, quantum speed reading, and quantum energy bar?

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Some time ago, China Telecom launched a service called "Quantum Secure Call".

When I saw the news, [subject] was shocked, and the first thing that came to my mind was

Quantum wave speed reading▼

Quantum Bracelet▼

Quantum Energy Bar▼

Of course, there is also the magical quantum entanglement communication in "The Three-Body Problem"!

Through this technology, the Trisolarans 4 light years away can monitor every move of the people on Earth with zero delay.

Apart from the fictional plot of The Three-Body Problem, it seems that everything related to quantum is somewhat NT.

So what exactly is this mysterious-sounding "quantum secret talk"?

According to China Telecom, if you need to apply for this service, you need to replace a SIM card that is pre-loaded with a quantum security key. When using a special quantum call app, you can make quantum calls in this way of "changing the card without changing the number."

In fact, this quantum call has nothing to do with the "quantum entanglement communication" in "The Three-Body Problem", nor does it have anything to do with the "quantum computing" and the strange "quantum energy" we often hear.

The core of the quantum call service launched by China Telecom is to use the characteristics of quantum to encrypt calls.

The security of communications is largely determined by the encryption method.

The secret key is like a key. The more complex and advanced the key is, the more difficult it is to crack the lock and the more secure the encryption method is.

So what is the key? For example, Tony sent a string of "in 55iw!" to Pepper, and Pepper was confused. At this time, a passerby who gave a bad review told her: "Read this string backwards."

When Pepper saw it, oh! It turned out to be "i miss u!", and then she beat Tony up.

In this process, "reading backwards" is the key to this mysterious code.

From the report, we can see that the special feature of quantum secure call service lies in the combination of quantum keys prepared using quantum information technology.

We also need to understand quantum.

Quantum is a microscopic physical concept. In modern physics, if a physical quantity has a smallest indivisible basic unit, then this physical quantity is quantized, and the smallest unit is called a quantum.

You should know that "quantum" has many special characteristics, including: quantum uncertainty, quantum non-cloning, quantum indistinguishability, etc.

By using these characteristics of quantum to prepare keys, "quantum-level" encryption can be achieved during communications.

The quantum information technologies that can currently be used to prepare quantum keys mainly include QKD (Quantum Key Distribution) and QRNG (Quantum Random Number Generation).

According to existing technology, it is still difficult to transmit the entire piece of information through quantum, and the cost-effectiveness is not high.

It is relatively simple to use quantum methods to make keys, so both parties can complete "quantum communication" in this "roundabout way".

Therefore, whether it is a QKD system or a QRNG system, this method is used to prepare keys to achieve the effect of quantum secure communication.

Take the QKD system as an example, and start the show! (If you are too lazy to read the following content, you can jump to the human language version)

First, Xiao Ming uses a random "ruler" called a "measurement basis" to create a string of random quantum information and sends it to Xiao Zhang through the telecommunications company's quantum channel.

Because the quantum information sent by Xiao Ming is random, Xiao Zhang does not know what the quantum information sent by Xiao Ming is.

So Xiao Zhang randomly used another "ruler" to "measure" this string of incomprehensible data.

However, this is a bit like the "base pairing" learned in biology, because the ruler and the data are random, so only when the "just right" ruler uses the "just right" scale to measure the "just right" data can you get the "correct result".

If the scales of the two "rulers" are different at the same position, then the answer at this position is wrong.

Xiao Ming: Can you show me your ruler?

Xiao Zhang: Okay.

Then, Xiao Zhang told Xiao Ming what his ruler looked like through the telecommunications company's ordinary channel.

After Xiao Ming receives the ruler sent by Xiao Zhang, he compares it with his own ruler, and then tells Xiao Zhang which scales on the ruler are correct through the ordinary channel.

Xiao Zhang uses the information sent by Xiao Ming to delete the wrong scale on the ruler, and then tells Xiao Ming the remaining correct measurement results. Finally, Xiao Ming confirms the correctness of Xiao Zhang's measurement results.

If the measurement result is correct, Xiao Ming will eliminate part of the quantum information, convert the remaining quantum information into a binary string as the key, and send a confirmation message to Xiao Zhang.

After Xiao Zhang received it, he eliminated the same quantum information, and the remaining binary string matched Xiao Zhang's key.

If the measurement results do not match, it means that there may be eavesdropping in the quantum channel.

This is because if someone attempts to eavesdrop and uses a ruler to measure randomly, the polarization state of the light quantum will change.

QKD: Someone is eavesdropping? Die!

The system will terminate the communication. Therefore, quantum key encrypted communication is highly sensitive to eavesdropping.

I have said a lot, and it doesn’t matter if you don’t understand it. In short, through several comparisons back and forth and using the physical properties of quantum, Xiao Ming and Xiao Zhang, the sender and the receiver, finally got the key that only the two of them had.

Next is human language: For example, if the content of the communication is a letter, then the encryption of the communication content is to lock the letter in a box. If there is no key, Mr. Wang next door will not be able to see the letter.

Therefore, the most important thing in encryption is to ensure that only Xiao Ming and Xiao Zhang have the key to unlock the door, and no third party can steal it.

The method of quantum encryption is to utilize the characteristics of quantum mechanics and use a series of complex methods to transmit the key to Xiao Zhang extremely securely.

What’s more interesting is that if Lao Wang next door wants to force open the box during the transmission, the box will be automatically destroyed immediately.

Lao Wang:???

In this way, a key is generated between the two parties for encrypted communication. This key is generated through a series of special means, so it has stronger encryption properties and more difficult decryption than ordinary calls.

The quantum encryption method it uses cannot be cracked mathematically, making eavesdropping even more difficult.

Lao Wang: It’s so hard for me!

At present, the construction of quantum channels needs to rely on optical fiber networks. China Telecom's optical fiber broadband resources naturally enable it to have the optical fiber resources required for quantum key distribution networks.

Does that mean that if we use China Telecom's quantum secret call service, the call will be completely secure?

That's not the case. Because at present, the quantum channel only exists between the two base stations that Xiao Ming and Xiao Zhang are connected to, and the communication between the mobile phone and the base station is still the traditional ordinary communication channel, so there is still the possibility of leakage.

Whether it is a fake base station or phishing WIFI, current communication eavesdropping often occurs between the terminal and the base station, and the current quantum encryption communication can only ensure the communication security between base stations.

Ah, this... From this point of view, there is still a lot of room for development in the promotion and popularization of communication security, and there is still a long way to go.

Moreover, there is another obvious weakness in QKD encryption. As we mentioned earlier, if someone eavesdrops on the quantum channel, the QKD system will immediately detect it and terminate the communication.

The guy next door, Mr. Wang, thought: If I can't get it, I'll destroy it! Although I can't eavesdrop on your communications, but since your connection will be disconnected as soon as I eavesdrop, why don't I just keep eavesdropping? I wonder how you can make phone calls anymore?

This is also the weakness of QKD: it is very afraid of DDos attacks.

Moreover, the connection of the "Quantum Secret Talk" line requires both the caller and the receiver to apply for this service and meet the relevant conditions, so its practicality may be questionable. [Subject] I think this service may be more suitable for those who have strong communication security needs, such as government, enterprises, military and business!

But this doesn't mean that we individual users don't need stronger communication security.

In the 2G and 3G era, when we handled important matters such as financial transactions, we had to go to banks and other specialized institutions with higher security levels.

In the 4G and 5G era, people have transferred more and more businesses to portable terminals such as mobile phones, and the security of these portable terminals is often much lower than that of traditional professional institutions;

The harm of eavesdropping on individual users may not seem significant, but in recent years, there have been more and more large-scale global information leaks, followed by the resale of various leaked information packages on the dark web...

Every time such an incident occurs, we have doubts about the security of our personal information.

When you think about it this way, an individual’s need for communication security cannot be ignored.

Therefore, it has to be said that the launch of such services is indeed a major step forward in protecting communication security.

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