In the hierarchical model, what is the role of the root Certificate Authority (CA)?

The root Certificate Authority (CA) plays a crucial role in a hierarchical trust model for digital certificates, which is foundational to secure communication over networks. Its primary function is to issue certificates to intermediate CAs. This is significant because the root CA is at the top of the certification hierarchy and is responsible for establishing the trust anchor upon which the rest of the certificate chain depends.

When a root CA issues certificates to intermediate CAs, it provides them with the authority to issue their own certificates to end entities, such as users or servers. This issuance forms a trust chain, where the integrity and legitimacy of the certificates issued by intermediate CAs can be trusted because they are ultimately backed by the root CA.

The root CA itself typically does not engage directly with end users or applications but serves as the highest level of trust in a Public Key Infrastructure (PKI). Its certificates are usually pre-installed in operating systems and web browsers, allowing for widespread trust in the chains of certificates that descend from it.

This hierarchy helps organize and manage certificates and their validations, ensuring that the ecosystem of trust remains secure, scalable, and easier to manage, with the root CA functioning as a critical lynchpin in that structure.