In the US, insults are not something for which you can be prosecuted. Calling someone a son of a bitch is not defamatory. No one believes you are really the child of a dog. So that is an opinion. Defamation requires a false factual statement. Truth is a complete defense.
What is Public Key Infrastructure (PKI)? Public Key Infrastructure (PKI) is a set of hardware, software, people, policies, and procedures needed to create, manage, distribute, use, store, and revoke digital certificates. In cryptography, a PKI is an arrangement that binds public keys with respective user identities by means of a certificate authority (CA). Wikipedia.org
The Public Key Infrastructure is a framework for using digital certificates and their associated keys to verify the identity of users and computers to other users, computers and applications. PKIs are important elements in network and Internet security because many communications, such as business and e-commerce transactions, are dependent on a reliable method to identify the parties to the transaction.