What Is HDCP and How Is It Used?

So, what is HDCP anyway? It is hard to keep track of all the tech acronyms you’ll find in the wild these days. Thankfully, HDCP is a pretty well-documented standard and it’s one you’ll see more with audio/visual equipment than anything in computing.

Today’s guide will be taking a closer look at HDCP, how it works, and its overall importance in the grand scheme of things. You’ve likely heard the acronym while shopping for a TV, so let’s dig deep to see what it actually means.

Defining HDCP

HDCP is short for High-bandwidth Digital Copy Protection, and as the name might imply is a form of DRM for audio and visual content. The copy protection scheme itself was debuted in 2000 and used DVI as the primary interface. Version 2.3 is the latest standard, and is primarily intended for HDMI with support for 4K content. There are a number of problems surrounding HDCP, which will be explored a little further.

How Does HDCP Work?

HDCP has a number of moving parts that actually dictate its overall function. You’ll primarily see it only on audio and visual content, like streaming video, Blu-rays, and so forth. You can further divide HDCP into device types, which will also be explored a bit. Do keep in mind this isn’t a full explanation of the mechanisms behind the copy protection, but rather a top-down look at its overall function.

Authentication

One of the most important aspects of HDCP is authentication. What this means is that the device playing content is authorized to do so. The authentication process is done starting with the source, in this case, a DVD, Blu-Ray, or set-top box used for the likes of cable and satellite television.

The source has to go to a recipient, which is generally done through the HDMI audio/visual standard. Once the source sees that it is a licensed and acceptable HDCP device, playback can begin.

Encryption

Following the authentication process, the transmitter sends the content to something called the sink. The sink is essentially just a TV or digital projector that has been licensed and authorized for HDCP compatibility. The sink has to work in conjunction with a repeater, which takes an encrypted digital stream from the source.

This encrypted signal is decrypted, processed, sent to the main display, and then re-encrypted. The encryption process as a whole allows users to watch whatever they’re hoping to watch, while also making sure that no unauthorized duplication can occur.

Revocation

HDCP as a whole utilizes a special sort of encryption that relies upon master keys for authentication. Like any other asymmetrical encryption protocol, you’ll need a licensed device on both ends to actually permit the passage of a key.

As you can imagine, piracy is a concern with any digital media. It doesn’t take much for the governing consortium behind the HDCP, the Digital Content Protection Agency, to revoke a compromised key. This is commonly done when a key is compromised, decrypted, or fraudulently generated.

Copy protection and digital piracy are engaged in a constant arms race, but the stream cipher utilized by HDCP makes it especially prone to third-party intrusion.

Where Is HDCP Used?

So, where will you find HDCP in use? You’ll see HDCP in use on many different devices. It is much rarer to find it in a computer, though the standard is actively supported on GPUs and processor chipsets.

Physical Media

Physical media is the most prominent use of HDCP, as you’ll find it in use with disc players like Blu-ray and DVD. One can argue against its efficacy all day, as you’ll often see news stories relating to the release of master keys and the like from poorly finished discs.

As physical media’s popularity continues to wane, it’ll be interesting to see whether up-to-date keys remain in use. Currently, you’ll still find HDCP 2.3 and lower keys in active use with the discs you might rent from a location like RedBox.

Paid Television Services

Paid television services are another extremely prevalent user of HDCP streams. You’ll find it in use with subscriptions like Spectrum and DISH TV. However, digital streaming services like Netflix, Hulu, Disney+, and others are likely also using HDCP.

This leads to interesting scenarios, like the 2015 leak of a 2.2 encryption key from an episode of AMC’s hit show Breaking Bad. The encryption protocol is thought to have been broken thanks to the metadata found in the head of the file.

That said, paid television services are likely to continue the use of HDCP for the foreseeable future. There isn’t a government-mandated need for the protection, but media distributors are overwhelmingly supporting the standard as a whole.

What Issues Does HDCP Pose?

Multiple Screens

One of the largest issues you’ll run across with HDCP is the use of multiple screens. More upscale home theater setups are likely going to stream video across multiple displays. This poses certain problems, as the intended key for a data stream might only work on a single television.

Now, the clearer solution would be to permit multiple keys to be issued per data stream. However, when you consider services like Netflix rely on higher subscription tiers to provide playback on more than one device, it runs into issues. You could very well be using the one streaming box to send digital video to another TV.

Lack of Backward Compatibility

Encryption standards are rarely going to have backward compatibility. It wouldn’t make much sense to leave the newer standard wide open to an older compromised key. However, this does present problems for users.

If you have an older 4K television, you’ll quickly encounter issues with HDCP 2.2 media. Version 2.2 has no backward compatibility as a whole, meaning you’ll need a brand-new TV or soundbar to use it. Your television might be in perfect working condition, but you’re locked out of newer content thanks to HDCP 2.2 or 2.3.

This isn’t a simple firmware fix in the making either. You can only update the HDCP version by purchasing a brand-new TV. Keeping new revisions of the encryption protocol relegated to hardware only can go a long way to prevent piracy. However, this is highly punitive to law-abiding users.

Other Issues

Since we’ve established HDCP is generally present on modern computers, this does present its own set of complications. Consider the usage of an Apple computer, like a MacBook or Mac Mini. HDCP activates as a switch when watching supported media.

Since HDCP is intended to prevent unauthorized broadcast of supported media, it can lead to issues with video teleconferencing software like Zoom and FaceTime. Now, some external monitors for Macs can switch off HDCP reporting automatically, but that isn’t a complete fix.

There are a number of latent issues with HDCP as a whole that bear mentioning, but that’s a subject for another article altogether. Simply put, like any other encryption standard, the end-user can run into the limitations of the system fairly quickly.

Is HDCP Important to Modern Media?

So, is this standard important to modern media? HDCP has a prominent place in modern media, and it will continue to for the foreseeable future. Digital media rules the roost when it comes to actual viewership, and companies are looking to safeguard their intellectual property.

It shouldn’t come as a shock in the future if there is a brand new revision of the encryption standard as a whole. While there are always going to be users seeking to break the code behind it as a whole, there is going to be a continual need for copy protection for media going forward.

The image featured at the top of this post is ©Sunshine Studio/Shutterstock.com.