This paper documents many of the PKI (Public Key Infrastructure) concepts, specifications, usage scenarios/decisions, and debugging in JUNOS Enhanced Services (JUNOS-ES). It is not meant to be just a step-by-step guide to configuring and using PKI on a Juniper device.

The document linked below includes an overview of PKI in JUNOS-ES. It also includes sample configuration scenarios and details on PKI administration, an FAQ (Frequently Asked Questions) section on JUNOS-ES PKI, as well as appendices regarding some CA administration and DOD PKI usage. 

This document is not a primer on the general concepts of PKI. There many sites on the web that can provide documentation on basic PKI concepts; such as RSA Laboratories for more information on crypto, RSA, and PKI.

JUNOS-ES IPSec VPN with PKI Certificates Primer [PDF]