China is the first country in the world to use passwords. The most difficult "password" to crack was also invented by China people. The anti-tangent phonetic notation method appeared in the late Eastern Han Dynasty, which is to annotate another word with two words, take the initials of the upper word and the finals of the lower word, and "cut" the pronunciation of another word. "Anti-cutting code" was invented by Qi Jiguang, a famous anti-Japanese general and strategist, on the basis of this anti-cutting pinyin. Qi Jiguang also specially compiled two poems as "codebook": one is: "Liu Bian strives for low gas, Berta strives for the sun. English and Mongolian are happy, clap your hands and know the gentleman "; Another song is: "Spring flowers are blooming, autumn mountains are blooming, guests need to sing in golden cups, and solitary lamps burn silver pots." In the eastern suburbs, crossing the West Bridge, the first day is urged by the sound of chickens, and bells are set to cover ditches. "
These two poems are all the secrets of anti-tangent code. Take the initials of 15 words before the last song and number them from 1 to 15 respectively; Take the vowels of the last 36 words, and the sequence number is 1 to 36. Then, the eight tones of pronunciation at that time were also numbered as 1 to 8, so as to form a complete "arc tangent code" system. How to use it: If the password sent back is 5-25-2, the control initial number 5 is "low", the vowel song number 25 is "west", the initial and vowel of the two words together are di, and the control tone is 2, the word "enemy" can be cut out. Qi Jiguang also specially compiled a "Eight-Tone Meaning Manual" as a teaching material for training intelligence personnel and signalmen.