TCL LCD32M61S3-MS19, Service Manual

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PART VII HDCP Section
High-bandwidth Digital Content Protection (HDCP) is a form of Digital Rights
Management (DRM) developed by Intel Corporation to control digital audio and video
content as it travels across Digital Visual Interface (DVI) or High-Definition
Multimedia Interface (HDMI) connections. The specification is proprietary, and
creating an implementation of HDCP requires a license .HDCP is licensed by Digital
Content Protection, a subsidiary of Intel. In addition to paying fees, licensees
agree to limit the capabilities of their products. For example, high-definition
digital video content must be restricted to
DVD quality on non-HDCP compliant video
outputs when requested by the source. DVD-Audio content is restricted to DAT quality
on non-HDCP digital audio outputs (analog audio outputs have no quality limits).
Licensees cannot allow their devices to make copies of content, and must design their
products in ways that "effectively frustrate attempts to defeat the content
protection requirements."
Each HDCP capable device has a unique set of keys; there are 40 keys, each 56 bits
long. These keys are confidential and failure to keep them secret may be seen as
a violation of the license agreement. For each set of keys a special key called a
KSV (Key Selection Vector) is created. Each KSV has exactly 20 bits set to 0 and
20 bits set to 1.
During the authentication process, both parties exchange their KSVs. Then
each device adds (without overflow) its own secret keys together according
to a KSV received from another device. If a particular bit in the vector
is set to 1, then the corresponding secret key is used in the addition,
otherwise it is ignored. Keys and KSVs are generated in such a way that
during this process both devices get the same 56 bit number as a result.
That number is later used in the encryption process.As result that, this
chassis adopts 24C04 to storage KSV and license makes digital signal
resource output.