What is the entity responsible for issuing and guaranteeing certificates, often set up privately for internal communications?

The entity responsible for issuing and guaranteeing certificates, particularly in the context of internal communications, is a Certificate Authority (CA). A CA operates within a public key infrastructure (PKI) and is tasked with verifying the identity of individuals or organizations before they receive a digital certificate. This certificate acts as a form of identification in electronic transactions, enabling secure communication by ensuring that data is encrypted and that the identity of the parties involved is authentic.

A CA can be either a public entity or a private entity that is used within an organization's internal network. When set up for internal communications, a private CA is usually established to issue certificates specifically designed for internal applications and services, allowing for greater control and security over the issuance process.

In contrast, an Intermediate CA or Subordinate CA is a lesser authority in the hierarchy of a PKI that acts on behalf of a root CA to issue certificates. While they do play a role in the overall certificate chain, they typically don't operate independently. A Registration Authority (RA) is responsible for accepting requests for digital certificates and authorizing those requests before they are processed by a CA, but it does not issue certificates directly.

Thus, the Certificate Authority is the core entity responsible for the issuance and guarantee of certificates for both internal and external