Overview

In cryptography, a certificate authority or certification authority (CA) is an entity that stores, signs, and issues digital certificates. A digital certificate certifies the ownership of a public key by the named subject of the certificate.

A certificate authority (CA) is a trusted entity that issues Secure Sockets Layer (SSL) certificates. These digital certificates are data files used to cryptographically link an entity with a public key. Web browsers use them to authenticate content sent from web servers, ensuring trust in content delivered online.

Trusted certificates can be used to create secure connections to a server via the Internet. A certificate is essential in order to circumvent a malicious party which happens to be on the route to a target server which acts as if it were the target. Such a scenario is commonly referred to as a man-in-the-middle attack. The client uses the CA certificate to authenticate the CA signature on the server certificate, as part of the authorizations before launching a secure connection.

The format of these certificates is specified by the X.509 or EMV standard.

What is certificate authority used for?

A certificate authority (CA) is a trusted entity that issues Secure Sockets Layer (SSL) certificates. These digital certificates are data files used to cryptographically link an entity with a public key. Web browsers use them to authenticate content sent from web servers, ensuring trust in content delivered online.

What is Microsoft certificate authority?

Microsoft Certificate Authority (CA) is part of the Windows Server operating system. A certification authority (CA) is responsible for attesting to the identity of users, computers, and organizations. The CA authenticates an entity and vouches for that identity by issuing a digitally signed certificate.

As of April 2023, below are the 6 largest authorities by absolute usage share:

1. IdenTrust | Market Share: 48.5%
2. DigiCert | Market Share: 14.5%
3. Sectigo (Comodo Cybersecurity) | Market Share: 13.4%
4. GlobalSign | Market Share: 6.7%
5. Let's Encrypt | Market Share: 6.4%
6. GoDaddy | Market Share: 5.3%