What is the primary purpose of a digital certificate?

The primary purpose of a digital certificate is to verify the identity of an entity. Digital certificates are used in public key infrastructure (PKI) to ensure that individuals, organizations, or devices involved in online transactions are who they claim to be. This is crucial for establishing trust in online communications, as the certificate links the entity's identity to a public key that can be used for encryption.

When a digital certificate is issued, it is signed by a trusted Certificate Authority (CA), which serves as a third-party verifier. Users and systems can check the validity of the certificate, thereby confirming the identity of the entity and establishing a secure connection. This process is fundamental for various applications, including secure email communication, e-commerce transactions, and secure website connections using SSL/TLS.

The other options do not align with the primary function of digital certificates. Encrypting speech transmissions represents a use case that might benefit from digital certificates, but it is not their main purpose. Similarly, while digital certificates are involved in ensuring secure communication, they do not inherently store sensitive data nor do they function as network traffic monitors.