HDCP (High-bandwidth Digital Content Protection) – digital content protection
The first HDCP version was developed by Intel and Silicon Image in 2000. The aim of HDCP is to protect the digital signal. The technology prevents unauthorized high resolution copies and is widely used by media companies.
HDCP is a proprietary technology. All manufacturers of equipment using HDCP technology must have a valid license and are charged a license fee. Also, the device must meet strict requirements. First of all, it must not allow to copy the broadcast. Each device marked with HD Ready logo must meet the HDCP data protection standard requirements. Popular devices using this protection system include Blu-Ray players and TV boxes. Any attempt to watch the movie on a non-HDCP compatible device will fail or the quality will be significantly worse.
The data stream coding process is relatively complex and in general consists in comparing and exchanging the special keys between the devices. Each device has a unique set of 40 keys, and a special public key (Key selection vector - KSV) created for a specific set. During authentication, the devices exchange their key selection vectors (KSV) and add its own keys together, comparing the values of respective bits. If the result of the comparison is positive for both devices and encoded connection is established using the above mentioned keys. The signal is encoded in streaming mode and each pixel is encoded.
Both the 56-bit keys and the 20-bit key selection vectors stored in the device are confidential. Failure to keep the keys secret may lead to legal consequences. If a particular set of keys is compromised, their corresponding KSV is added to a revocation list burned onto new discs in the high definition formats.