1. In a network including a key exchange system and a plurality of network devices, a computer-implemented communication sender verification method comprising: creating, in the key exchange system, a user account for a communication sender, the user account storing user identification information, user authentication criteria and user indicia; verifying, by at least one of an administrative user of the key exchange system and a certificate authority and a third party application, that the user identification information associated with the user account identifies the communication sender; specifying, by at least one of an administrative user of the key exchange system and a certificate authority and a third party application, a classification of the communication sender and associating the classification with the user account; preferably associating a certificate for generating encryption key pairs to the user account; associating the private key of a key pair to a network device of the communication sender; associating, to the user account of the communication sender on the key exchange system, the public key of a key pair; receiving, from a network device of a communication recipient, a request for at least one public key and user indicia associated to at least one user account; and, transmitting, to the network device of the communication recipient, at least one public key and user indicia associated to at least one user account.