Lets Talk About Classical Cryptography

Cryptography has a wide range of applications in our lives and serves as the foundation of information security. From the emergence of cryptography in ancient times to the development of modern cryptography, the cryptographic techniques used by people are called classical cryptography. Classical cryptography is mainly concerned with the confidential transmission of information, and the corresponding deciphering methods. The design of classical cryptographic algorithms usually depends on the creativity of the designer, and the security depends on the secrecy of the algorithm. Let's take a look at some common classical ciphers. 1. “Fan Qie” Code During the Ming Dynasty, the “Fan Qie” code invented by Qi Jiguang used two poems as the "codebook" (see Table 1 and 2). The initials of the first poem’s lyrics were assigned numbers 1-15 while the vowels of the second poem’s lyrics were assigned numbers 1-36. Then the eight tones of pronunciation at that time were then assigned numbers 1-8, forming a complete “Fan Qie code” system.