# About Certification Authority

To use security or signature functions based on public key cryptography, you obtain the public key of another party. For secure Internet communication, a good method is needed to validate the authenticity of the public key of a person whom you do not personally know. A Certification Authority as a third party plays the role to prove the association between the public key and the person who owns it, and issues a certificate according to the certificate standard format X. 509. Each user obtains the root certificate from the Certification Authority to trust it. Using the public key contained in the root certificate, you can verity that the certificate was issued by the authentic Certification Authority.