What is a Certificate Authority (CA)?

What is a Certificate Authority (CA)?


A Certificate Authority (CA) is an organization entrusted with signing digital certificates. The CA verifies the identity and legitimacy of the company or individual requesting a certificate. Upon successful verification, the CA issues a signed certificate.


During the SSL handshake, when a server presents a certificate to a client (e.g., a web browser), the client attempts to verify the signature against a list of trusted signers. Web browsers typically come with lists of CAs that they implicitly trust to identify hosts. If the authority is not in the list, such as with some sites that sign their own certificates, the browser will alert the user that the certificate is not signed by a recognized authority and ask if they wish to continue communication with the unverified site.

1Byte offers SSL certificates signed by the Comodo Certificate Authority (now Sectigo CA). This CA is recognized by 99% of web browsers, ensuring that browsers will not display any security errors when connecting to a site secured by Comodo (now Sectigo).