The Cipher Lesson from Xiang Xiaotong

"First of all, ciphers have a historical lineage. The East developed one system of ciphers, while the West developed another. Through dissemination and integration via the Arab world, they reached their peak during World War I and World War II, and have continued to develop until the present. They're already nearing the end of the road." Xiang Xiaotong took a sip of Eight Treasure Porridge as she spoke.

"Near the end of the road?" Song He was stunned.

"We'll save that for last." Xiang Xiaotong kept him in suspense.

Song He nodded.

"When I was studying ciphers back then, I had the feeling that the ciphers created by humanity evolved much like living organisms. They went through a process of inheritance and gradual change from one generation to the next, with each generation making minor adjustments based on the ciphers of the previous one." Xiang Xiaotong continued.

"Let me first explain some of the historical development of cryptography and intelligence studies so you can understand it more clearly."

"Okay." Song He held a pot sticker between his teeth as he watched his teacher attentively.

"There was a period in history when the Arab region was extremely prosperous. Relying on trade routes, the Arabs collected massive quantities of books and texts in Egyptian, Chinese, Babylonian, Sanskrit, Farsi, Syriac, Hebrew, and Roman, then translated them into Arabic on a large scale." Xiang Xiaotong paused. "Have you heard of this?"

"I have. The so-called Arabic numerals were a product of that period. The ancient Indians invented them, the Arabs learned them, and then spread them to Europe." Song He thought for a moment. "Translating languages is somewhat like deciphering ciphers. Combined with the rise of mathematics, it pushed the development of cryptography in the Arab world?"

"Exactly! There was another crucial factor: religious