Technical point of view | Changan Wanglou? This is just the tip of the ancient Chinese cryptography application.

01 Introduction

Tianbao three years, January 14th, Yongzheng. One hundred and eight squares of Chang'an City are bathed in the bright sunshine of the morning. The West City Department Department stationed on the watchtower to announce the opening of the West Market. Chang'an City suspended the curfew and the city was boiling. In the context of this event, the hidden murders in Chang'an City began to appear, and the Turkic Weapons waited for an opportunity to move, and a thrilling counter-terrorism operation began.

Figure | Network

Zhang Xiaojing was able to take advantage of the Wanglou and its communication system in the process of chasing the wolf. Each square in Chang'an City has two or three towers, which monitor the city in real time and use different combinations of purple and white squares to quickly pass the message to Zhang Xiaojing and the intelligence center Jingan, so that they can make quick decisions.

Figure | Network

Wuhou on the upper floor holds a set of password communication system, which is a guarantee that the message can be transmitted safely. To put it simply, the well-trained Wuhou, the well-known square, will first encode the message into a number represented by the calculation according to the established codebook, and then use the purple-white square to represent and pass the number. Upon receiving the message, Jingan Si Dawanglou Wuhou turned the color square back to the number and decoded the message.

Figure | Calculations presented by the China Science and Technology Museum

It is worth mentioning that in ancient China, the Spring and Autumn Period and the Warring States Period began to use the counting method, which left a glorious record in the history of mathematics. The ancient generals were even more "strategic" and decided to win thousands of miles away.

02 Ancient Chinese password application
Today, passwords are widely used in life, and all aspects of life such as bank card swiping, social communication, and blockchain transactions are constantly using cryptography to protect financial security and communication security. In ancient times and in modern times, passwords were generally used in military activities, both in China and in foreign countries. The ancient Roman military commander Caesar used the replacement encryption technology to transmit messages in the military, and the deciphering of the Enigma cipher machine accelerated the end of World War II. There were also many records about password applications in ancient China.
2.1 Yin Fu Yin Shu Tong Mi
For more than a thousand years before BC, Jiang Ziya helped the Zhou Wu Wang Xing Zhou to destroy the business with a full-fledged strategy, which laid a solid foundation for the establishment of the longest dynasty in Chinese history. It is said that the "Six-Yun" written by Jiang Ziya is more hailed as the ancestor of the military family. Among them, Jiang Ziya proposed to use the Yin and Yin books for confidential communication.
Ginger teeth express eight kinds of battle results in eight different lengths, such as a one-footed female character that means a big victory. Only the king and the master will understand the meaning of these eight kinds of yin, so that the enemy is hard to see through it. It can be seen that the message that the yin can be transmitted is relatively small. If the two armies want to cooperate with the army, they can use the yin book to contact the military. When the two armies liaison, the military situation was split into three parts, and each of the three commanders sent a copy. Only when they joined together could they understand the entire military situation. The Yinshu can be seen as a prototype of a more typical secret sharing scheme.
2.2 The match of the tigers
In 1973, a Qin-shaped tiger -shaped soldier– Qin Duhu was unearthed in Xi'an. As a precious cultural relic of the national treasure level, the tiger symbol is now in the Shaanxi History Museum. The Hufu is divided into two halves, the right half is in the hands of the monarch, and the left half is in the hands of the general. In normal times, the general can hold the left half of the symbol to order soldiers under 50 to take military measures. Any soldier who wants to mobilize more than 50 people will be required to act in conjunction with the left and right characters. But in an emergency, such as a wolf, the general can also act with a half-feature.

Figure | Qin Duhu of the Shaanxi History Museum

We can see that Hyundai’s certification in cryptography also inherits this spirit, and further develops the certification of “what I have” into a variety of certifications such as “what I know” and “what is the natural attribute”. the way.
2.3 Qing Ge word demolition
In 684 AD, Wu Zetian abolished Tang Zhongzong Li Zhe, and opened the era of the Heavenly Kingdom. Xu Jingye launched a military attack against Wu Zetian in Yangzhou. At the same time, Luo Binwang’s famous "Wu Jingye for Wu Jing" called for the world to save the country. At this time, a letter from the prime minister Yan Yan and Xu Jingye was obtained by Wu Zetian. There is nothing else in this letter, just the word "green goose". Wu Zetian deciphered the code law, that is, the word "green goose" was taken apart, and it became "December, I am self-contained", which is the meaning of the time to meet. Therefore, Yan Yan was taken by Wu Zetian on the spot.
It is worth mentioning that the Qinggee incident has not been recorded in the official history such as Zi Zhi Tong Jian and Tang Shi. In addition, Luo Binwang is one of the four masters of the early Tang Dynasty. At the age of seven, he became a famous poet of the Tang Dynasty.
2.4 Prince Edward dreams of breaking the book
White peony is made from the processing of alum. Dissolve the white peony in the water, the writing brush will disappear after writing and drying in the white water, and the words will reappear after re-immersion in the water. Baishui is a kind of steganography widely used in ancient Chinese military and political activities. Strictly speaking, steganography is not cryptography, but it is often used for secret communication.
In the late years of Emperor Kangxi of the Qing Dynasty, the northwest war began. The prince of the prince wanted to go out and take the position of the general, and he came back. Therefore, the people who asked the people to use the script to send letters, asked people to recommend themselves as the generals. Later, others discovered the script and told Kangxi. At this point, the plan to restore the identity of the Crown Prince has completely failed.
03 Postscript
Classical cryptography played a major role in activities such as ancient and modern military. Today, modern cryptography demonstrates its power in everyday life and is an important part of blockchain technology. The ontology technology team will conduct research and analysis on relevant cryptography technologies, such as threshold technology, zero-knowledge proof, and aggregate signature, providing important technical support for blockchain security and the extensive application of blockchain.
The completion of this article refers to a large amount of information including the website of the National Cryptography Administration and the website of the Shaanxi History Museum. Due to space limitations, it is not listed one by one. I would like to thank you here.
Note: Some of the pictures and texts in this article are from the Internet and are for communication and learning purposes only and do not have any commercial use.

Cover image source: https://107cine.com/stream/112883