Hcip/hcie Routing & Switching / datacom Reference Dictionary Series (19) comprehensive summary of PKI knowledge points (public key infrastructure)

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One 、PKI brief introduction

PKI Public Key Infrastructure Public key infrastructure

CIA Model
Confidentiality Confidentiality
Integrity integrity
Availability Usability

Two 、Confidentiality Confidential technology

Introduction to encryption technology

3、 ... and 、 Encryption technology classification According to the usage of the key

1 Symmetric encryption （ Shared key encryption ）

Encryption and decryption use the same key
characteristic ： Fast Compact ciphertext Key management is complex For the transmission of large amounts of data

2 Asymmetric encryption （ Public key encryption ）

encryption Decryption uses a different key （ Public key Private key ）
characteristic ： Slow speed The ciphertext is not compact Key management is simple Usually only used for digital signature

Public key encryption Private key decryption
Private key encryption Public key decryption

Four 、 The combination of two encryption algorithms

In practical use Communication parties usually use public key cryptography to exchange key materials
Both parties finally calculate the key Using symmetric cryptography to encrypt the actual data
Combination of the two Ensure encryption speed and security
Public key cryptosystem - Asymmetric cryptosystem - Exchange key material
Slow speed The ciphertext is not compact Key management is simple Usually only used for digital signature
Shared cryptosystem - Symmetric cryptosystem - Encrypt actual data
Fast Compact ciphertext Key management is complex For the transmission of large amounts of data

A Use the key material B Public key encryption then B use B Private key decryption of Get the material
A Then encrypt the plaintext with the key material B Decrypt the plaintext with the decrypted key material
But there are still problems
A How to confirm that the public key obtained is B Of ？
How to ensure that data is not destroyed in the transmission process ？