What is HDCP: The Complete Guide

What is HDCP: The Complete Guide

Copyright protection is a tricky, but important component of any digital medium, and that includes physical media. HDCP, or High-bandwidth Digital Content Protection, is one such system used in devices like Blu-ray players, though it also sees use in digital streaming devices, services, and game consoles.

What is HDCP? It's a way for companies to prevent the unauthorized copying of their protected properties. It's not perfect, and there are ways it has been circumvented by a determined few, but HDCP is the industry standard for protecting some of the most expensive media properties at some of the world's largest companies.

What is HDCP?

Developed by Intel, HDCP is a digital content protection system that safeguards audio and video when it's being transmitted down a particular connection. It is supported by DisplayPort, HDMI, and the legacy DVI. In order to use it, companies have to pay a license fee, and to be considered compatible, devices have to meet certain standards of copy protection themselves.

Although a distinctly different technology, HDCP is sometimes confused with HDMI, since HDCP generations include HDCP 1.4 and 2.2, while recent HDMI generations include 1.4, 2.0, and 2.1. They are also often labeled alongside each other on source and display devices. As close as they are, though, these are two very different technologies.

Where HDMI is very much hardware, HDCP is decidedly software. It's effectively, a combination encryption algorithm and a handshake system. HDCP encrypts the signal coming from a digital source device, like a Blu-ray player, and then performs a digital "handshake" with a compatible display or another device, where the two devices share secret codes to see if they are both legitimate and support HDCP. If that handshake is accepted, then the signal can be decrypted and displayed.

However, if the display or any other device along that chain is not HDCP compliant, then the signal will not be decrypted, which either leaves the display unable to show anything or at best a corrupted signal. Sometimes audio can be transmitted and played by non-HDCP compliant devices, but it will be of a lower quality. 

There are three main protocols of HDCP: Authentication, Revocation, and Encryption. 

     Authentication - The HDCP transmitter confirms that the HDCP receiver is authorized to receive the HDCP content.

     Revocation - If the HDCP receiver is determined to be invalid or compromised, then the authentication protocol is aborted.

     Encryption - The HDCP transmitter encodes the Audiovisual Content, and then sends it to the HDCP receiver, where it is decoded, and formatted for human consumption.

Protocols of HDCP: Authentication, Revocation, and Encryption

Modern displays all support HDCP as a matter of course, so you're most likely to run into issues of compatibility with older HDTVs that did not support HDCP when they launched. It can also happen if you use a cable or splitter which does not support HDCP, even if the display itself does support it.

While HDCP is most commonly used with physical media, like Blu-ray discs, it is also used in some streaming services. For example, Disney and Warner Bros. use HDCP to encrypt and protect almost all of their own shows, so if you encounter them on a streaming service, particularly their first-party services, you may find that you run into issues if you use a display that isn't HDCP compliant.

Although HDCP is a popular solution for major media companies in preventing media piracy, it has drawn some criticism for the way it can prevent legitimate use of a media owner, if their hardware isn't compatible with HDCP, but is otherwise capable of displaying the content.

Several versions of HDCP have been released over the years, with the main difference being that the latest versions support higher-resolution content. Newer versions also feature more robust protection against copying the protected content, although some have claimed to have bypassed these protections too.

The latest version is HDCP 2.3 and is designed to work with the delivery of 4K content. As 8K content becomes more commonplace, we may see a new HDCP version to support it.

It's important to understand what is HDCP and how it works if you're building anything outside of a standard source player-to-TV connection. Although almost all modern displays and potential source devices, like Blu-ray players, consoles, and desktop PCs, all support HDCP, if you want to use splitters, switches, or other hardware to create a more complex A/V system, you need to understand HDCP in order to avoid it preventing you from watching and listening to your favorite content.

Cable Matters HDMI Extenders over Ethernet are HDCP Compliant for viewing protected content at ranges of 300 feet.

Shop HDCP Compliant HDMI Extenders

How HDCP Works

HDCP-compatible devices have their own unique sets of encryption keys which they exchange with one another when trying to transmit HDCP-protected content from one device to another. Those encryption keys both confirm that each device is HDCP compliant, and are used to encrypt the content as it is transmitted, before being decrypted at the other end. That prevents man-in-the-middle attacks from harvesting the unprotected media during transit.

HDCP Encryption Process

While early versions of HDCP only supported direct device to display transmission of HDCP-protected content, every version of HDCP since 2.0 has also supported network transmission. This makes it possible to connect a greater number of HDCP devices together, along with networking hardware like switches, repeaters, and routers. 

As with device-to-device connections, however, any networked A/V system must support the same HDCP standard in order for the transmission to be successful. 

HDCP Compatible Devices & Cables

In order to be certified as HDCP compliant, a device manufacturer has to receive a license from Digital Content Protection, a subsidiary of Intel that handles licensing for HDCP. Only devices that meet the specifications and standards set by Digital Content Protection are granted a license, but since it's supported by some of the biggest media companies, it's all but mandatory to get HDCP compliance for any source device or display.

In order to receive the license, device manufacturers must pay an annual license fee, must guarantee that the device will not transmit HDCP-protected content to non-HDCP-compliant devices, and must frustrate attempts to defeat content protection systems.

You can tell whether your display or device is HDCP compliant from its specifications. These are often listed on the manufacturer's website or in the manual. Alternatively, as it's such an important feature of modern devices, you will often find HDCP compliance showcased on the box in some form. 

The same goes for HDCP-compliant cables. Look out for an HDCP logo or specification on the box, or in the manual you received with the cable.

Although you don't need to use HDCP-compliant devices and cables if you're watching older media, or watching your own ripped content from a local media service, it's all but mandatory if you want to watch anything modern. Blu-ray players all support HDCP and HDCP is a required feature for streaming content from Netflix and Amazon Video. Disney+ requires HDCP 2.2 support for 4K ultra HD and HDR content.

Cable Matters offers a wide range of HDCP-compliant products, including cables, splitters, and adapters. You'll typically find HDCP version support in the features section on compatible products, like this HDMI 2.1 cable. If you're buying a Cable Matters cable on Amazon, you'll find the HDCP information under the About this Item heading.

HDCP Compliance Issues

Typically HDCP support is a black-and-white issue: it either works because the device and display are HDCP compliant, or it doesn't, because they aren't. Trying to connect a Chromecast, Roku Streaming Stick, or Amazon Fire stick to an older HDTV that doesn't support the correct version of HDCP (or any version of HDCP) will often see an error message of some sort appear on the display.  The same would happen if you have a splitter or cable within the A/V system that isn't compatible with the version of HDCP your content requires to play.

But there are incidents where issues can occur which aren't so clear cut, and that's where HDCP compliance issues are worth investigating.

Any time you feel like HDCP might be the cause of content not displaying correctly or at all, you should double check all the components of your A/V system support the same HDCP version, and the version that's required by the particular media. It's no good having a system that is HDCP 1.4 compliant if you're trying to play something that requires HDCP 2.2 support.

In the case of cables where it isn't always obvious if they're HDCP compliant, you could switch to an alternative cable that you know for sure does meet that spec. You can find HDCP information on Cable Matters cables on our store pages or on our Amazon product pages.