The sender of a public key would be authenticated by a:
A digital certificate is an electronic document that declares a public key holder is who the holder
claims to be. The certificates do handle data authentication as they are used to determine who sent
a particular message. A certificate authority issues the digital certificates, and distributes, generates
and manages public keys. A digital signature is used to ensure integrity of the message being sent
and solve the nonrepudiation issue of message origination. The registration authority would perform
most of the administrative tasks of a certificate authority, i.e., registration of the users of a digital
signature plus authenticating the information that is put in the digital certificate.