IPTV streaming encryption

[johnzack]

Hi guys, we are running small IPTV application for our hotel client, basically they have RF input with HD channels, we use hdmi qam modulator , we connect input via loopout and output the signal over IP, with cisco switch we distribute it over the building, it was a small hotel so they had no problem with physically plugging off the cable, if client decides not to pay extra 5 bucks a day for this service. They have been expanding over the time and now they came to the point when they want to have a normal conditional access system. Are there any ways to encrypt traffic with passive device (firewall-like-gateway) and decrypt it with STBs, what options do I have? Thank you in advance