This article will explain the concepts and processes of digital certificates, signatures, verification, asymmetric encryption and symmetric encryption in the TLS protocol, as a section of my column "Quick Start Tutorial for Computer Network Protocols".
Certificate & Root Certificate
The function of a digital certificate is to prove the identity of an asset. For example, the digital certificate in the TLS protocol is often used to prove the identity of the server, as shown in Figure 1 below: Figure 1 is a certificate issued to
blog.csdn.net
, used To indicate that the service corresponding to blog.csdn.net is communicating. The issuer of the certificate is rapidSSL and is valid for one year. According to the certificate path, the issuer of CA rapidSSL is DigiCert, as shown in Figure 2:
Figure 2
We know from Figure 2 that DigiCert is the root certificate, and the user and issuer of the root certificate are both themselves. The root certificate is very important in the entire certificate inspection system, so it is usually preset in the operating system or browser in advance. Check the root certificate in Windows, as shown in Figure 3: Figure 3 should always check
your
updated certificate list to see if there are suspicious root certificates. If an untrusted certificate is imported into the root certificate list, it will cause some security problems, such as man-in-the-middle attacks.
Certificate Field Meaning
The picture below is a blog.