For client software which does not support authentication (there are plenty ESRI ArcGIS online, GBM Konect and Tech One to name a few) , We have implemented a proxy which captures the username / password via an auth-key and forwards to the main server by decrypting them on the server side.
Here is a sample WMTS getcapabilties query passing via the proxy:
Here is a sample WMTS gettile query getting an image tile (please set Accept: image/jpeg or Content-Type: image/jpeg in the request header to receive the correct converted content):
Here is a sample getlayers query to return a JSON encoded list of layers over a particular point. This is our basic solution to handle a Catalog query:
Please contact us and request an authkey to be generated for your special needs.