DERViewer is an ASN.1 structure viewer plugin.
It can be used to view digital certifcates, pkcs#7 data and other security related files.
You can download the plugin from http://o-regan.org/plugins/derviewer/index.html
Copy the jar file to the plugins folder underneath your Idea installation. I've tested it with Aurora and Ariadna.
You can give feedback either here or to firstname.lastname@example.org