High-bandwidth Digital Content Protection (HDCP) has been used (most commonly, over HDMI links) to protect the path between the player and display from unauthorized access.
Unfortunately, the version of HDCP used to protect HD Blu-Ray content was compromised quite some time back. Content owners decided that 4K content would require an updated protection mechanism, and this prompted the creation of HDCP 2.2.
This requires updated hardware support, have made it quite messy for consumers since HDMI 2.0 surfaced. Early 4K adopters (even those with HDMI 2.0 capabilities) will probably need to upgrade their hardware again, as HDCP 2.2 can’t be enabled via firmware updates due to security restrictions. HDCP requires the firmware to be in chipsets only to prevent easy reverse engineering.
UHD Netflix-capable smart TVs don’t need to worry about HDCP 2.2 for playback of 4K Netflix titles. The TV has the required content protection integrated into the logic board.
Consumers just need to remember that whenever ‘premium’ 4K content travels across a HDMI link, both the player and the display must support HDCP 2.2. Otherwise, the player will automatically downgrade the transmission to 1080p (assuming that an earlier HDCP version is available on the display).
If an AV receiver is present in the display chain, it needs to support HDCP 2.2 as well. New AV receivers are now coming to market with HDCP 2.2 support but check with vendors to be sure that the model has all of the features needed.