PKI uses public key cryptography to allow for secure message exchange between participants online. More importantly it allows for uniquely identifying users/entities online, i.e., what is the public key of John Smith. John Smith will be validated the same way he would be validated in real life (ID, passport) and a digital certificate that contains John’s public key will be created and disseminated as needed. PKI, effectively tries to solve identity and secure distribution of public keys. Certificate Authorities (CAs) are the entities responsible for creating the digital certificates and are federated for scalability.