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1. Definition of Password

According to the "Cryptography Law of the People's Republic of China", passwords are defined as follows:

Cryptography refers to technologies, products and services that use specific transformation methods to encrypt and protect information and provide security authentication.

2. Definition of Cryptography

Cryptography is the technical science of coding and deciphering codes.From the definition, we can know that cryptography is divided into two main branches:

• Cryptanalysis: Focuses on the creation of cryptographic systems and encrypting information to ensure the secure transmission of information.
• Cryptanalysis: Focuses on the analysis and cracking of cryptographic systems, attempting to reveal the content of encrypted messages.

For the five attributes of information security (confidentiality, integrity, authentication, non-repudiation, and availability), you can jump to read my other article:【Cryptology】Five Attributes of Information Security

3. Basic Model of Cryptographic Algorithms

The basic model of cryptographic algorithms includes: the five elements of cryptographic systems and the basic requirements of cryptographic algorithms

(1) Five Elements of Cryptographic System

The five elements of a cryptographic system are: plaintext space, ciphertext space, key space, encryption algorithm, and decryption algorithm. For more details, you can jump to read my other article:【Cryptology】Five Elements of Cryptography

A cryptographic algorithm is essentially a mathematical function with secret parameters that follows certain mathematical rules to transform data.

• Knowing the secret parameters, the inverse is very easy
• Without knowing the secret parameter, inversion is not feasible

(2) Characteristics of cryptographic algorithms

An ideal cryptographic system should be highly reversible in the encryption process, irreversible without a key, and highly sensitive to the selection and protection of the key. Only such a cryptographic system can provide reliable information protection in practical applications.

A good cryptographic system should meet at least two conditions:

1. When the plaintext and encryption key are known, it is easy to calculate the ciphertext; when the ciphertext and decryption key are known, it is easy to calculate the plaintext.
2. Without knowing the decryption key, it is impossible to recover the plaintext from the ciphertext.