Match the following S/MIME digital signature Kerberos Public-key infrastructure (PKI) A. formed by taking the message digest of the content to be signed and then encrypting that with the private key of the signer. B. the set of hardware, software, people, policies, and procedures needed to create, manage, store, distribute, and revoke digital certificates based on asymmetric cryptography C. the defacto standard for remote authentication. D. security enhancement to the MIME Internet e-mail format standard, based on technology from RSA Data Security.