Certificate authority

Updated: 06/06/2021 by Computer Hope
Certificate authority diagram.

Alternatively called a certification authority or CA, a certificate authority is an organization or entity that verifies the authenticity of public key SSL/TLS encryption certificates. When you visit a website that uses HTTPS, such as Computer Hope, your web browser receives the public key certificate of the website, digitally signed by a CA. Your web browser assumes the CA is trustworthy, and decrypts its digital signature to receive the public key of the website. Encrypted communications with the website can then be established using that key.


The CASC (Certificate Authority Security Council) is a consortium that comprises many of the world's largest CAs. Its stated purpose is to advocate the development, operation, and support of CAs, and educate the public about best practices for secure communication on the Internet.

In 2021, the CASC was renamed to the PKI (Public Key Infrastructure) Consortium, with a renewed focus on engagement and participation.

Major CAs

Some notable certificate authorities include:

Computer acronyms, Encryption, Internet, Security terms