As well as the classic passwords and representative figures in various stages of cryptography, as well as their landmark achievements in history.
Keywords: classic password; Cryptography development; encrpytion tachniques
With the development of information and digital society, people's awareness of the importance of information security and confidentiality is constantly improving, and cryptography, which plays an important role in information security, has become an indispensable part of information security courses. Cryptography is a subject whose purpose is to study secret communication, that is, to protect the information to be transmitted in secret and prevent the third party from stealing it.
Cryptography has been produced as early as 400 BC, and the history of human using passwords is almost as long as that of using words.
The development of cryptography can be divided into four stages: 1, ancient encryption methods.
2. Classic password.
3. Modern passwords.
4. Modern passwords.
First, the old encryption method
The endless demand from applications is always the direct driving force to promote technological invention and progress.
Records in stone carvings or historical books show that many ancient civilizations, including Egyptians, Hebrews and Assyrians, have gradually invented cryptographic systems in practice.
In a sense, war is a catalyst for scientific and technological progress.
Since the war, human beings have been facing the demand of communication security, and cryptography has a long history.
The ancient encryption method originated around 400 BC. The Spartans invented the "Seta code", that is, a long strip of paper was spirally wound on a polygonal rod and characters were written from left to right along the horizontal direction of the rod. Rotate after writing a word, and then write another line from left to right until it is finished.
After reading, the text information on the note is confusing and incomprehensible. This is the ciphertext, but you can see the original information by winding it around another stick of the same size.
This is the earliest cryptographic technology.
In ancient China, there were also records of hiding the true meaning or "secret words" in a specific position of a poem or a picture scroll in the form of Tibetan poems, Tibetan poems, Tibetan poems and Tibetan paintings. Most people only pay attention to the superficial artistic conception of a poem or a painting, but they don't pay attention to or find the hidden "argot" in it.
For example, in "Water Margin", in order to draw Lu Junyi into the partnership, Wu Yong and Song Jiang, two "wise men", gave birth to a story of "Wu Yongzhi earned a jade unicorn", taking advantage of Lu Junyi's fear of avoiding the "mass annihilation" to account for four hexagrams:
There is a boat among the reeds, from which Jie Jun and Russia swam.
If an upright man can know this, he can't escape from the bow.
The word "Lu Junyi opposes" is hidden.
As a result, it became evidence of government punishment, and finally "forced" Lu Junyi to Liangshan.
More widely known is Tang Bohu's I Love Chou-heung: I paint the blue river with a leisurely water color, and I love worrying about the maple leaves on the pavilion at night.
The autumn moon shines on the Buddhist temple, and cigarettes fill the front of the building.
Second, the classic password
The encryption method of classical passwords is generally text replacement, which is realized by manual or mechanical transformation.
Classical cryptosystem has initially embodied the embryonic form of modern cryptosystem, which is more complicated than ancient encryption methods and has little change.
Here are some examples of classic passwords.
1. drum password
In ancient times, in order to ensure the confidentiality of their communication, some simple methods were consciously used to encrypt information.
For example, the ancient Greeks used a stick called scytale to encrypt information six years ago.
The messenger first spirally winds a sheepskin strip on the stick, then writes the information to be written on it in a certain order, then opens the sheepskin strip roll and sends the letter to the recipient through other channels.
It is not easy to decrypt the contents without knowing the thickness of the stick, but the recipient can decrypt the letter with the same long-handled stick as agreed with the writer in advance.
Step 2 mask the password
/kloc-The masked password invented by cardano, a physicist and mathematician in Milan in the 6th century, can design the opening of the grid in advance and combine the information to be transmitted with some other irrelevant symbols into invalid information, which makes it difficult for the interceptor to analyze the valid information.
3. Chessboard password
We can build a table so that each character corresponds to a number, which is the label of the row where the character is located, not the label of the column.
This converts plaintext into a series of digital ciphertexts.
4. Caesar password
According to records, during the Roman Empire, Julius Caesar designed a simple shift cipher for wartime communication.
In this encryption method, the letters of plaintext are recursively in alphabetical order, and the same letters are recursively in turn, so that the ciphertext can be obtained. The decryption process is just the opposite of the encryption process.