1. A method, comprising: establishing a secure communications line between an entity device and a client device, the entity device need not have specific knowledge of cryptographic functions of a platform service; receiving, at one client device from the entity device, an invitation to authenticate a secure communications line with the entity device using an inviter-invitee protocol, the invitation including an authentication parameter; downloading, at the client device from a platform service, a client application based at least in part on the invitation, the platform service comprising a public key infrastructure, privilege management infrastructure, and at least one of certification authority, registration authority, attribute authority, or hardware security module, or a combination thereof; authenticating an identity of a user of the client device based at least in part on the authentication parameter included in the invitation; creating, at the client device, certain cryptographic keys, including at least one public-private key pair and a digital identity token upon receiving authentication approval from the platform service; transmitting, from the client device to the platform service, a public key of the public-private key pair of the client device which is subsequently received by the entity device; receiving, at the client device from the platform service, a public key corresponding to the inviting entity device with that device's digital identity token; and transmitting, from the client device to the platform service, a request to create the digital identity token; wherein the invitation includes a unique invitation code; and wherein the downloading the client application occurs based at least in part on the unique invitation code.