Final answer:
A hierarchical PKI has a central authority and a top-down structure, while a mesh PKI is decentralized with multiple interconnected CAs.
Step-by-step explanation:
Hierarchical and mesh PKIs are two different organizational structures for Public Key Infrastructures (PKI). In a hierarchical PKI, there is a central authority, called the root Certificate Authority (CA), which issues digital certificates to subordinate CAs. These subordinate CAs can then issue certificates to end entities, such as users or devices. This creates a hierarchical chain of trust, where each level of the hierarchy is responsible for validating the certificates of the level below it.
In a mesh PKI, there is no central authority. Instead, multiple CAs are interconnected in a peer-to-peer manner. Each CA in the mesh is responsible for issuing and validating certificates. This creates a decentralized network of trust, where each CA can independently verify certificates without relying on a central authority.
In summary, hierarchical PKIs have a top-down structure with a central authority, while mesh PKIs have a decentralized structure with multiple interconnected CAs.