Digital certificates are electronic documents that contain the public key of an entity and are signed by a trusted third party, called a Certificate Authority (CA). Digital certificates are used in Transport Layer Security (TLS), a protocol that provides secure communication over the Internet, by enabling the following functions:
* Server identity: The client can verify the identity of the server by checking the validity of its digital certificate and the signature of the CA.
* Data confidentiality: The client and the server can use the public keys in their digital certificates to establish a symmetric key for encrypting the data exchanged between them.
* Non-repudiation controls: The client and the server can use their private keys to digitally sign the data they send, which provides proof of origin and integrity of the data, and prevents the sender from denying the transmission.