What is a security protocol that combines digital certificates for authentication with public-key data encryption?

A security protocol that combines digital certificates for authentication with public-key data encryption is the Transport Layer Security (TLS) protocol. TLS uses digital certificates to verify the identities of the parties involved in a communication, ensuring that they are legitimate. Public-key encryption is then employed to secure the data transmitted between these parties, protecting it from eavesdropping and tampering. This combination enhances the overall security of online communications, such as those conducted over the internet.