Yes, HDMI is powered. The HDMI specification requires that all HDMI-compliant devices support HDCP (High-Bandwidth Digital Content Protection). HDCP is a data encryption and authentication protocol that helps prevent unauthorized copying of digital content. HDCP involves the use of selectable keys that are embedded in the HDMI signal.HDMI receivers use these keys to encrypt and decrypt the incoming HDMI signal. In order to support HDCP, all HDMI-compliant devices must be powered.
HDMI cables are also powered. The reason for this is that some cable manufacturers include features such as built-in equalizers and/or active signal boosters in their cables. These features require power in order to function properly.