In recent years, an increasing number of security incidents, such as information leaks and network attacks, underscore the growing importance of security in Internet communication.

Passwords, as a critical method for maintaining information security, have become an integral part of Internet communication.

However, did you know that the history of passwords can be traced back to the 5th century BC? Today, let's unravel the mysterious and fascinating history behind this essential aspect of cybersecurity.

The evolution of cryptography can be broadly divided into three stages: the classical cryptography stage, the modern cryptography stage, and the contemporary cryptography stage. Cryptography has transitioned from being regarded as an art to a fully-fledged science over the years.

During the extended period leading up to the end of the 9th century, cryptography began to take shape and gradually develop. In this stage, cryptography was passed down as an art, with content substitution and replacement achieved manually using tools such as paper, pen, or other simple instruments.

One of the most well-known encryption techniques from this era is Caesar's cipher. This method involves "encrypting" all the letters of a message by offsetting them backward or forward by a fixed number in a single alphabet.

Similarly, by using the offset as a decryption key, the ciphertext can be decrypted.

The Virginia cipher represents an encryption algorithm that utilizes a series of Caesar ciphers to form a cipher alphabet.

In essence, the same message is encrypted using multiple alphabets. Each bit of the message corresponds to a column number, and the filled key serves as a row number, facilitating the location of the intersection of rows and columns in the table – the encrypted characters. This approach enhances the complexity of the cipher, making it more challenging to decipher.

A significant leap in the field of cryptography occurred when Claude Shannon published "Communication Theory of Secrecy Systems." This groundbreaking work not only established the foundation of information theory but also introduced two design principles – obfuscation and diffusion – into cryptography.

This marked a crucial juncture where cryptography transitioned from being an art to a scientific pursuit. Subsequently, complex substitution and replacement processes were undertaken manually or with the assistance of electric machinery.

Cryptography found its prominence, prominently featured in classic spy movies. Its pivotal role is exemplified by the British deciphering of the German Enigma encryption machine. The Enigma machine, leveraging the principles of obfuscation and diffusion, presented a formidable challenge as its key was updated daily, rendering manual decryption nearly impossible.

As mechanical and electromechanical technologies matured, coupled with the demand for telegraphy and radio communication, the rotary machine emerged as a dedicated cryptographic device for encryption.

Comprising a keypad and a set of rotating wheels, each wheel could represent any combination of the 26 letters of the alphabet. Upon completing the rotation of wheels and gears, the original letters were replaced by encrypted ones.

The Enigma encryption machine, an exemplary representative of the rotary cipher, utilized this method, where entered letters passed through wheels and gears to form a new circuit, illuminating the bulb corresponding to the encrypted letters.

This journey through the history of cryptography highlights the transition from ancient manual methods to sophisticated machines, laying the groundwork for modern cybersecurity practices and shaping the landscape of secure internet communication.