Which entity is responsible for issuing and revoking user certificates?

The Certification Authority (CA) plays a crucial role in the management of digital certificates, which are essential components in ensuring secure digital transactions and communications. The CA is responsible for issuing user certificates to individuals or organizations after verifying their identity, ensuring that the certificate holder is who they claim to be. This verification process helps to establish a chain of trust within a digital environment.

Furthermore, the CA has the authority to revoke certificates when necessary. This could occur if a certificate is compromised, if the holder no longer needs the certificate, or if the information within the certificate is invalidated (for instance, if the entity changes its name or domain). By managing both the issuance and revocation of certificates, the CA helps maintain the integrity and security of digital communication.

Other entities mentioned, such as end users, transaction processors, and stakeholder groups, do not have the authority to manage the issuance or revocation of certificates like a CA does. The specific roles of these entities focus on different aspects of digital transaction processes and security but do not encompass the entire lifecycle management of user certificates.