Disc copy protection

From Emulation General Wiki
Revision as of 08:56, 4 May 2024 by Ahayri (talk | contribs) (→‎See also)
Jump to navigation Jump to search

Disc copy protection refers to various methods used to prevent unauthorized copying of data from CDs, DVDs, and other optical discs. These methods aim to protect copyrighted content like software, movies, and music. See this section for copy-protection measures within HD-DVD and Blu-ray discs.

DRM icons

Contents

Common Copy Protection Measures

Since the era of floppy disks (circa 70s-90s) saw a constant battle between software developers and copy pirates. To protect their valuable software, developers employed various copy protection methods, creating a fascinating game of technological innovation.

70s-90s (On-Disk and Off-Disk Copy Protections)

On-disk methods involved manipulating the data on the floppy disk itself to hinder copying:

  • Non-Standard Disk Formats: Software might format the disk in a way incompatible with standard copying programs, requiring specialized tools.
  • Invalid Checksums/CRCs (Cyclic Redundancy Checks): Adding errors to checksums, data verification tools, would cause copied disks to fail integrity checks.
  • Hidden Data: Data essential for the software's operation could be hidden in unused sectors or encoded in special ways, making it difficult for copying software to detect and copy accurately.
  • Bad Sectors: Deliberate introduction of bad sectors on the disk would cause errors during the copy process, leading to incomplete or unusable copies.
  • Index/Offset Data Alignment: Misaligning data sectors or index information could confuse copying software, resulting in garbled data on the copy.
  • Weak/Flaky Bits: Data bits on the disk could be weakened intentionally, causing them to be misread during copying, leading to program instability on the copied disk.

Off-disk methods relied on external factors to prevent unauthorized copying:

  • The Code Wheel: A physical wheel with codes printed on it, included with the software. The program might prompt the user for specific codes from the wheel during installation, preventing copying without the physical wheel.
  • Manuals with Unlock Codes: Unlock codes printed in the software manual were required during installation, making copying without the manual difficult.
  • Copy Protection Software: Separate software programs might be included on the disk, checking for the presence of the original media before allowing installation.

As with any security measure, these copy protection methods eventually faced their match. Skilled programmers developed tools and techniques to bypass these protections, creating "cracks" that allowed users to copy software. This ongoing battle between protection and cracking fueled the innovation in both areas throughout the floppy disk era.

LGR: The History of DRM & Copy Protection in Computer Games

The rise of digital distribution and more robust security measures eventually rendered floppy disk copy protection obsolete. However, the ingenuity and creativity behind these early methods remain a fascinating chapter in the history of software protection.

2000s
  • Digital Rights Management (DRM): DRM restricts how a disc's content can be accessed or copied. It may require online activation, limit installations to a certain number of devices, or disable specific features on copied discs. See PCGamingWiki: Types of DRM methods on Discs.
  • Middleware: SecuROM is one of the most well-known examples, SecuROM (introduced in 1998) employed a combination of techniques. It used disc encryption, monitored system resources for signs of copying, and sometimes included features like copy limitation or online authentication. LaserLock is a middleware relied on a special authentication layer burned onto the disc itself. During installation, the software would verify the presence of this layer to ensure it was an original disc. SafeDisc is Similar to SecuROM, utilized disc encryption and copy protection features. It was also known for its aggressive copy protection measures, which sometimes caused conflicts with legitimate software or hardware. See PCGamingWiki DRM#Middleware section.
  • CD-checks: Software on the disc searches for specific data patterns or physical characteristics to verify it's an original disc and not a copy.
  • Dummy files: Irrelevant data files are added to the disc to confuse copying software and increase the disc size beyond its standard capacity, making it difficult to copy entirely.
  • Illegal tables of contents: Errors are introduced in the data layout information on the disc, tricking copying software into making an unusable copy.
  • Over-sizing/over-burning: The disc is encoded with more data than its standard capacity allows. This may prevent some copying software from handling it properly.
  • Physical errors and bad sectors: Intentional imperfections are introduced on the disc's surface to prevent reliable reading by copying tools.
Many older software programs and games are unusable today because some of the original copy protection methods relied on activation servers that are no longer operational.
Tech Tangents: Digital Decay Of 2000's PC Game DRM
MVG: SecuROM - The PC CD-ROM DRM that broke games

Disc Reliability vs. Digital Storage

While digital storage boasts superior convenience and accessibility, it relies on proper backups to ensure long-term data integrity. Media failure or file corruption can still lead to data loss. Physical discs, on the other hand, present their own challenge: disc rot. This is a gradual chemical breakdown of the disc's reflective layer, rendering the data unreadable over time. Disc rot is a concern for long-term data archiving[1].

Bypassing Copy Protection

This section is for informational purposes only.

Some software cracks bypass copy protection checks, allowing installation and use of software without the original disc. These cracks, often called "NoCD" or "NoDVD" cracks, are distributed on illegal sources. See ROM_&_ISO_sites#Bypassing_Copy_Protection section.

Emulation

  • Daemon Tools can act as emulators for middleware like SecuROM. These emulators essentially trick the software into thinking the original protected disc is present, allowing it to run without the actual disc.
  • DiscCheckEmu can bypass copy protection measure that rely on "Disc Checks." Disc Checks involve the software verifying the presence of specific data patterns on the disc. DiscCheckEmu can potentially spoof these checks, deceiving the software.
  • SafeDiscLoader target specific versions of middleware like SafeDisc. They might utilize techniques like DLL (Dynamic Link Library) hooking to emulate disc checks or bypass other protection mechanisms employed by that particular middleware version.
DOSBox-X issue page: SafeDisc / SecuROM emulation for games

See also

External links

Retrieved from "https://emulation.gametechwiki.com/index.php?title=Disc_copy_protection&oldid=86486"