Which technology prevents illegal copying of digital signals during transmission?

The technology that prevents illegal copying of digital signals during transmission is High-Bandwidth Digital Content Protection (HDCP). HDCP is specifically designed to encrypt and protect high-definition digital content as it travels from one device to another, such as from a Blu-ray player to a television or between devices in a home theater setup.

By implementing HDCP, manufacturers can ensure that the content cannot be intercepted and copied illegally during its transmission. It works by requiring both the source device and the display device to support HDCP and to authenticate each other before allowing the content to be transmitted. This security protocol is essential for protecting the copyrights associated with digital media and is widely adopted for HD and UHD content delivery.

The other technologies mentioned do not specifically focus on the encryption and protection of high-definition digital signals during transmission in the same way that HDCP does. For example, Digital Content Security may refer to broader measures for protecting digital rights but lacks the specific application and function of HDCP.