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Certificate Authority (CA)

An entity that issues digital certificates to authenticate users and websites.

Understanding Certificate Authorities (CA)


CAs play a crucial role in SSL/TLS encryption, ensuring that websites, applications, and services use secure connections. When a website uses HTTPS, the CA verifies its identity and issues an SSL/TLS certificate, allowing users to trust the connection. Organizations also use private CAs for internal security, securing corporate networks, emails, and software applications.

Types of Certificate Authorities


Root CA

  • The highest level of trust in the PKI hierarchy.

  • Signs and issues certificates for subordinate/intermediate CAs.

Intermediate CA

  • Sits between the Root CA and end-user certificates.

  • Adds security by preventing direct Root CA exposure.

Public vs. Private CAs

  • Public CAs (e.g., DigiCert, GlobalSign, Let’s Encrypt) issue certificates for public websites.

  • Private CAs issue certificates for corporate networks, VPNs, and internal systems.

Common Applications


  • SSL/TLS Certificates: Encrypts web traffic and ensures website authenticity.

  • Code Signing Certificates: Verifies software integrity and authenticity.

  • Email Encryption Certificates: Secures email communications with S/MIME.

  • Device Authentication: Ensures secure communication between IoT devices.

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