Historical research on classification of Classical Cryptography

Cryptography is now being applied frequently in people’s daily lives. Their bank passcode, computer password, and digital signature all are applications of cryptography. Inside cryptography, Classical Cipher is a basic and important area as modern cryptography is developed from Classical Cryptography. By making a consummate system of Classical Cryptography, it increases people’s interest in exploring basic cryptography principles. This essay focuses mainly on the topic of classification of Classical Cipher. By reading related materials like books, journals, magazines and so on, the historical research came out the conclusion as the Classical Cipher can be classified as Substitution Cipher, Polyalphabetic Substitution Cipher, and Transposition Cipher. In each class, the essay mentioned several cipher examples, how they encrypt and decrypt the text, and how they can be broken. Caesar Cipher, Simple Substitution Cipher are examples of Substitution Cipher. Vigenere Cipher is mainly discussed inside the Polyalphabetic Substitution Cipher section. In Transposition Cipher part, Scytale and Rail Fence Cipher are listed to demonstrate traits of the Transposition Cipher.