HDCP – What is HDCP? Introduction to HDCP Functions
The function of HDCP is to ensure that high-definition signals transmitted through HDMI or DVI are not illegally recorded; The HDCP technology specification is led by Intel. When users engage in illegal copying, this technology will interfere and reduce the quality of the copied images, thereby protecting the content.
HDCP (High bandwidth Digital Content Protection): High bandwidth digital content protection technology. The era of HDTV (High Definition Television) is approaching, and HDMI has emerged to adapt to the high bandwidth of high-definition television. HDMI is a high-definition digital interface standard that provides high bandwidth for lossless transmission of digital video and audio signals. In order to ensure that high-definition signals transmitted through HDMI or DVI are not illegally recorded, HDCP technology emerged. The HDCP technology specification is led by Intel. When users engage in illegal copying, this technology will interfere and reduce the quality of the copied images, thereby protecting the content.
HDCP protects video signals from start to finish, which means that every aspect of the entire playback system must support the HDCP protocol. If the monitor does not support the HDCP protocol, it will not be able to play high-definition programs properly and can only see black or low-quality programs.
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HDCP mainly includes three basic contents: verification protocol, pixel encryption, and renewability. Firstly, the sender verifies whether the receiving device is authorized to receive encrypted data by verifying the legitimacy of the received data information through a verification protocol. The transmitter and receiver exchange a 40 bit key selection vector (KSV) with each other, and both parties perform independent operations on the obtained KSV and their own private key. The results of the operations are compared, and if the binary values are equal, the transmitter can determine that the receiver is suitable for HDCP.
If the legitimacy verification in the previous stage is passed, the sender and receiver exchange and share the key in the verification protocol to complete the data encryption and decryption process. The encryption of the transmitter is achieved by XORing the 24 bit raw pixel data and the 24 bit encrypted data generated by the HDCP encryptor to obtain 24 bit encrypted pixel data. After receiving the encrypted pixel data, the receiver performs an XOR operation with the 24 bit encrypted data encrypted by the receiver HDCP encryptor. Due to the identical structure and initial values of the receiver HDCP encryptor and the transmitter HDCP encryptor, the encrypted data is restored through two XOR operations.
When it is necessary to revoke the legitimacy of the receiver, it is accomplished through the renewability of HDCP. This section of HDCP identifies and cancels devices that are unauthorized or whose KSV has been placed on the ‘revocation list’. Avoiding the illegal theft of copyrighted information caused by the leakage of private device keys and KVS of legitimate HDCP receivers for some reason.