Both public and private keys can be used for encryption and decryption.
Public keys are usually shared and used for encryption.
The difference between symmetric and asymmetric encryption is whether the decryption keys are the same among the group of users.
Asymmetric encryption was born after symmetric encryption to make up for the disadvantage of asymmetric encryption.
The electronic signature exists on the e-certificate. The e-certificate is a third party acting as an official third party (with a high degree of credibility), providing the signature for the certificate and further providing the identity proof guarantee for the two parties in the process of communication.
References:
Segmentfault.com/a/119000000…