A digital certificate is a file containing public key owner information and public key digitally signed by a Certificate Authority (CA).

1. As an authoritative, trustworthy and impartial third-party organization, the Certification Center (CA) is responsible for providing digital certificate services for various certification needs.

2. The digital certificates issued by the certification center all comply with the X.509V3 standard.

The 3.X.509 standard has been widely accepted in formatting public key cryptography.

4.X.509 certificates have been used in many network security applications, including IPSec (IP Security), SSL, SET, and S/MIME.