8. Briefly describe the classification of cryptographic technology, how to use it for identity identification, and what are its advantages and disadvantages.

Cryptosystem is divided into private key encryption technology (symmetric encryption) and public key encryption technology (asymmetric encryption).

1, symmetric cryptosystem

Symmetric cryptosystem is a traditional cryptosystem, also known as private key cryptosystem. In a symmetric encryption system, encryption and decryption use the same key. Because the encryption and decryption keys are the same, both parties who need to communicate must choose and save their same key, and each party must trust the other party not to disclose the key, so as to realize the confidentiality and integrity of data. For a network with n users, n(n- 1)/2 keys are needed, and the symmetric encryption system is effective when the user group is not very large. However, for large-scale networks, when the user group is huge and widely distributed, the distribution and preservation of keys becomes a problem.

2. Asymmetric cryptosystem

Asymmetric cryptosystem, also known as public key encryption technology, is proposed for the defects of private key cryptosystem. In public key encryption system, encryption and decryption are relatively independent. Encryption and decryption will use two different keys. The encryption key (public key) is open to the public and can be used by anyone. The decryption key (secret key) is only known by the decryptor, and illegal users cannot calculate the decryption key according to the public encryption key, which can be called public key cryptosystem.