Copy protection

Copy protection, also called content protection or copy prevention, refers to measures used to enforce copyright. These tools aim to prevent the unauthorized reproduction of media like films, music, software, and video games. You can find these protections on many physical formats, including DVDs, Blu-ray discs, and audio CDs. They are also used for digital files distributed over the internet. While media corporations use this term, some critics prefer "copy control" or "copy prevention." They argue "copy protection" suggests the technology is always successful, even though many copies can still be made. A more technical term used by the World Intellectual Property Organization is "technological protection measures," or TPMs. These are tools used to restrict how a work is accessed or used.

There are several ways that software manages how it is used. One method is node locking, which ties a piece of software to one specific computer. Another method involves floating licenses, which are also called indirect licenses. In a floating license system, a fixed number of users can use the software at the same time across a large group, like a company. This is different from a direct license, which is issued to a specific user. For example, an activated Microsoft product uses a direct license that is locked to the PC where it is installed. Some software also uses electronic licensing, where users can purchase and activate specific features online. To keep these systems safe from hackers, companies use software antitamper methods.

Digital rights management, or DRM, is a broader concept often confused with copy protection. While copy protection focuses on stopping copies, DRM includes managing many different types of rights. For instance, DRM can manage video rentals that expire after a certain amount of time. Some forms of copy restriction are not even digital. In the world of downloads, companies use a process called "traitor tracing." This allows them to customize each download so it is unique to a specific user. This makes it much harder for someone to share a digital file without being detected.

From a business perspective, companies use these tools to protect their revenue. In 1990, unauthorized copying caused $2.4 billion in lost revenue in the United States alone. This loss of money is a major reason why companies propose stricter copyright laws, such as PIPA. Companies believe the cost of implementing protection is worth it to prevent "casual copying." Casual copying happens when consumers use machines to make copies for their friends. However, some experts argue that people who get free copies would not have bought the product anyway. Others suggest that free copies might actually increase profits by introducing people to new music or bands.

Despite these efforts, stopping all copying is a massive technical challenge. As long as a "writer" machine exists to create blank media, copies can be made. Every piece of media also requires a "player," such as a DVD player or a computer, to be read. A player could theoretically be built to read a disc and immediately write an exact copy to another one. There is also a problem known as the "analog hole." This means that if a human can hear music, they can record it with a microphone. If a human can see a film, they can record it with a video camera. By tapping into headphone jacks or speaker outputs, users can often make high-quality copies.

The history of software protection has been a long struggle between publishers and "crackers." Crackers are programmers who defeat protection systems as a hobby. In the early days, software was often shared on audio cassettes, making copying unreliable and slow. When floppy disks became common, unauthorized copying became a bigger problem. In the 1980s, experts like Jerry Pournelle argued that protection often just inconvenienced honest users. He noted that for every new protection scheme, a hacker was ready to break it. In 1985, it reportedly took crackers three weeks to break a system used by dBASE III.

Some companies have even faced backlash for how they use these tools. In the late 1980s, some Microsoft applications were criticized because their protection caused unexpected sounds or messages. This led the company to remove protection from some software. Other users found that software like Lotus 1-2-3 was difficult to use because of its security measures. In the end, the use of copy protection involves a difficult balance. Companies want to protect their work from mass duplication, but they must also ensure the product remains easy for paying customers to use.