There are two main types of copy-protection: The kind that launches a program to keep you from ripping the CD The kind that purposefully makes a CD defective (cracks and pops in the audio). This kind is rather easy to spot, as it doesn't have the 'audio CD' logo anywhere on it. Copy Protect is a copy protection tool that converts your media files, song covers, creative videos and presentations etc. Into executable files. These files can only be accessed in limited authorized devices. Be free to highlight your talent without the fear of copyright infringements. CD copy protection is achieved by assuming certain feature levels in the drives. The CD Digital Audio is the oldest CD standard and forms the basic feature set beyond which dedicated audio players need no instructions.
CD/DVD copy protection is a blanket term for various methods of copy protection for CDs and DVDs. Such methods include DRM, CD-checks, Dummy Files, illegal tables of contents, over-sizing or over-burning the CD, physical errors and bad sectors. Many protection schemes rely on breaking compliance with CD and DVD standards, leading to playback problems on some devices.
Protection schemes rely on distinctive features that:
- can be applied to a medium during the manufacturing process, so that a protected medium is distinguishable from an unprotected one.
- cannot be faked, copied, or retroactively applied to an unprotected medium using typical hardware and software.
Technology[edit]
Filesystems / Dummy files[edit]
Most CD-ROMs use the ISO9660file system to organize the available storage space for use by a computer or player. This has the effect of establishing directories (i.e., folders) and files within those directories. Usually, the filesystem is modified to use extensions intended to overcome limitations in the ISO9660 filesystem design. These include Joliet, RockRidge and El Torito extensions. These are, however, compatible additions to the underlying ISO9660 structure, not complete replacements or modifications. The most basic approach for a distinctive feature is to purposely fake some information within the filesystem. Early generations of software copied every single file one by one from the original medium and re-created a new filesystem on the target medium.
Sectors[edit]
A sector is the primary data structure on a CD-ROM accessible to external software (including the OS). On a Mode-1 CD-ROM, each sector contains 2048 bytes of user-data (content) and 304 bytes of structural information. Among other things, the structural information consists of
- the sector number, the sector's relative and absolute logical position
- an error detection code (EDC), which is an advanced checksum used to detect (if possible) read-errors
- an error correction code (ECC), an advanced method of detecting and correcting errors
Using the EDC and ECC information, the drive can detect and repair many (but not all) types of read-error.
Copy protections can use these fields as a distinctive feature by purposely crafting sectors with improper EDC/ECC fields during manufacture. The protection software tries to read those sectors, awaiting read-errors. As early generations of end-user soft/hardware were not able to generate sectors with illegal structural information, this feature could not be re-generated with such soft/hardware. If the sectors forming the distinctive feature have become readable, the medium is presumed to be a copy.
A modification of this approach uses large regions of unreadable sectors with small islands of readable ones interspersed. Most software trying to copy protected media will skip intervals of sectors when confronted with unreadable ones, expecting them all to be bad. In contrast to the original approach, the protection scheme expects the sectors to be readable, supposing the medium to be a copy when read-errors occur.
Sub-channels[edit]
Beside the main-channel which holds all of the user-data, a CD-ROM contains a set of eight sub-channels where certain meta-information can be stored. (For an audio CD, the user-data is the audio itself; for a data CD, it is the filesystem and file data.) One of the sub-channels — the Q-channel — states the drive's current position relative to the beginning of the CD and the current track. This was designed for Audio-CDs (which for a few years were the only CDs), where this information is used to keep the drive on track; nevertheless the Q-channel is filled even on into the CD-ROM itself but part of user-controlled data.
A part of an unprotected CD-ROM may look like this (simplified):
Sector's logical address | ... | 6551 | 6552 | 6553 | 6554 | 6555 | 6556 | 6557 | ... |
---|---|---|---|---|---|---|---|---|---|
Sector's content | ... | Jack | and | Jill | went | up | the | hill | ... |
Cd Copy Protection Removal Software
When the drive is told to read from or seek to sector 6553, it calculates the physical distance, moves the laser-diode and starts reading from the (spinning) disc, waiting for sector 6553 to come by.
A protected CD-ROM may look like this:
Sector's logical address | ... | 6551 | 6552 | 6553 | 6553 | 6554 | 6555 | 6556 | 6557 | ... |
---|---|---|---|---|---|---|---|---|---|---|
Sector's content | ... | Jack | and | Jill | Mary | went | up | the | hill | ... |
In this example, a sector was inserted ('Mary') with a sector-address identical to the one right before the insertion-point (6553). When the drive is told to read from or seek to sector 6553 on such a disc, the resulting sector-content depends on the position the drive starts seeking from.
- If the drive has to seek forwards, the sector's original content 'Jill' is returned.
- If the drive has to seek backwards, the sector's twin 'Mary' is returned.
A protected program can check whether the CD-ROM is original by positioning the drive behind sector 6553 and then reading from it — expecting the Mary version to appear. When a program tries to copy such a CD-ROM, it will miss the twin-sector as the drive skips the second 6553-sector, seeking for sector 6554.
There are more details about this technique (e.g. the twin-sectors need to be recorded in large extents, the SubQ-channel has to be modified etc.) that were omitted. If the twin sectors are right next to each other as shown, the reader would always read the first one, Jill; the twin sectors need to be farther apart on the disc.
Data position measurement[edit]
Stamped CDs are perfect clones and have the data always at the same position, whereas writable media differ from each other. Data Position Measurement (DPM) detects these little physical differences to efficiently protect against duplicates. DPM was first used publicly in 1996 by Link Data Security's CD-Cops. SecuROM 4 and later uses this protection method, as do Nintendo optical discs[citation needed].
Changes that followed[edit]
The Red Book CD-DA audio specification does not include any copy protection mechanism other than a simple anti-copy flag. Starting in early 2002, attempts were made by record companies to market 'copy-protected' non-standard compact discs. Philips stated that such discs were not permitted to bear the trademarkedCompact Disc Digital Audio logo because they violate the Red Book specification. There was great public outcry over copy-protected discs because many saw it as a threat to fair use. For example, audio tracks on such media cannot be easily added to a personal music collection on a computer's hard disk or a portable (non-CD) music player. Also, many ordinary CD audio players (e.g. in car radios) had problems playing copy-protected media, mostly because they used hardware and firmware components also used in CD-ROM drives. The reason for this reuse is cost efficiency; the components meet the Red Book standard, so no valid reason existed not to use them. Other car stereos that supported CD-ROM discs containing compressed audio files (such as MP3, FLAC, or Windows Media) had to use some CD-ROM drive hardware (meeting the Yellow Book CD-ROM standard) in order to be capable of reading those discs.
In late 2005, Sony BMG Music sparked the Sony CD copy protection scandal when it included a form of copy protection called Extended Copy Protection ('XCP') on discs from 52 artists.[1] Upon inserting such a disc in the CD drive of a computer running Microsoft Windows, the XCP software would be installed. If CD ripper software (or other software, such as a real-time effects program, that reads digital audio from the disc in the same way as a CD ripper) were to subsequently access the music tracks on the CD, XCP would substitute white noise for the audio on the disc.
Technically inclined users and computer security professionals found that XCP contains a rootkit component. After installation, XCP went to great lengths to disguise its existence, and it even attempted to disable the computer's CD drive if XCP was forcibly removed. XCP's efforts to cloak itself unfortunately allowed writers of malware to amplify the damage done by their software, hiding the malware under XCP's cloak if XCP had been installed on the victim's machine. Several publishers of antivirus and anti-spyware software updated their products to detect and remove XCP if found, on the grounds that it is a trojan horse or other malware; and an assistant secretary for the United States' Department of Homeland Security chastised companies that would cause security holes on customers' computers, reminding the companies that they do not own the computers.
Facing resentment and class action lawsuits[2] Sony BMG issued a product recall for all discs including XCP, and announced it was suspending use of XCP on future discs. On November 21, 2005 the Texas Attorney General Greg Abbott sued Sony BMG for XCP[3] and on December 21, 2005 sued Sony BMG for MediaMax copy protection.[4]
United Kingdom position[edit]
The provisions of law allow for redress to buyers of Audio CDs with Copyright-Protection. The Copyright, Designs and Patents Act 1988 contains provisions in section 296ZE part VII that allow for '[a] remedy where effective technological measures prevent permitted acts'.
In practice, the consumer would make a complaint to the copyright holder of the Audio CD, usually a Record Label. The complaint would contain a request to the holder of the copyright to provide a 'work-around' in order to make use of the copy-protected CD, to the extent that a non-copyright protected CD could be used lawfully. Where the consumer believes the copyright holder has not been reasonable in entertaining the request, they are within their rights under the Act to make an application to the Secretary of State to review the merits of the complaint and (if the complaint is upheld) to instruct the copyright holder to implement a work-around circumventing the copyright protection.
Schedule 5A of the Copyright, Designs and Patent Act 1988 lists the permitted acts, to which the provisions of section 296ZE apply (i.e. lists the cases in which the consumer can use the remedy, if the copy protection prevents the user doing a permitted act).
See also[edit]
References[edit]
- ^'Archived copy'. Archived from the original on 2008-12-24. Retrieved 2008-12-24.CS1 maint: archived copy as title (link)
- ^BBC NEWS | Technology | Sony sued over copy-protected CDs
- ^Texas Attorney General
- ^Texas Attorney General
External links[edit]
Retrieved from 'https://en.wikipedia.org/w/index.php?title=Compact_Disc_and_DVD_copy_protection&oldid=919728271'
![Cd Copy Protection Cd Copy Protection](/uploads/1/2/6/5/126572661/622728279.jpg)
This is a list of notable copy protection schemes for CD and DVD.
For other medias, see List of Copy Protection Schemes.
Sony Cd Copy Protection
Commercial CD protection schemes[edit]
- CD-Cops
- Requires the user to enter CD-code (or reads embedded CD-code) that describes geometry of CD to correctly locate data on the disc.
- SafeDisc (versions 1-5)
- Adds unique digital signature at the time of manufacturing which is designed to be difficult to copy or transfer so that software is able to detect copied media.
- SafeCast
- The encryption key will expire after pre-determined date so the media can be used only temporarily. Also used to implement trial editions of programs.[1]
- SecuROM
- Limits the number of PCs activated at the same time from the same key.
- StarForce
- Asks for Serial ID at install or startup to verify the license.
- TAGES
- Verifies authentic copy by checking existence of 'twin sectors' which are sectors with same logical address but different data. However, twin sectors may be hard to read in order to copy but are easy to write.
Commercial DVD protection schemes[edit]
- Analog Protection System
- Adds pulses to analog video signals to negatively impact the AGC circuit of a recording device so the images on copied DVDs becomes garbled.
- Sony ARccOS Protection
- Inserting corrupted sectors in areas where normal players will not access but ripping software does to trigger errors during replication.
- Burst Cutting Area
- Writing barcode in circular area near the center of the disc (referred to as burst cutting area) which cannot be written without using special equipment.
- DVD-Cops
- See CD-Cops in previous section.
- DVD region code
- Restricts region where media can be played by matching region number with configuration flag in DVD players.
- LaserLock
- Includes hidden directory on the CD containing corrupted data which will cause errors while being copied.
- ProtectDISC Software
- Adds unique digital signature to the CD or DVD that cannot be transferred from copy to copy. A solution for software and games on CD or DVD provided by Protect Software.
- ProtectDISC Video
- Prevents ripping software to analyze the structure of the DVD. A solution for Video-DVDs provided by Protect Software.
- SafeDisc (version 4)
- See SafeDisc (versions 1-5) in previous section.
- SecuROM
- See previous section.
- TAGES
- See previous section.
Commercial Audio CD/DVD protection schemes[edit]
- Cactus Data Shield
- Works by intentionally violating Red Book CD Digital Audio standards, such as erroneous disc navigation and corrupted data, prevents successful ripping of the data. However, the original disc itself does not play correctly in some CD/DVD players.
- Wavy data track[2]
- Discs' data track is wavy instead of straight, so only discs with the same wavy-shaped data track will be playable.
- Extended Copy Protection (XCP)
- Installs software on the computer after agreement to EULA at the first time the media is inserted, and the software will watch for any ripper software trying to access the CD-drive. This copy protection can be defeated simply by using a computer that is not running Microsoft Windows, not using an account with administrative privileges, or preventing the installer from running, and has long since been discontinued due to a public relations disaster caused by the software behaving identically to a rootkit.
- Key2Audio
- Another deliberate violation of the Red Book standard intended to make the CD play only on CD players and not on computers by applying bogus data track onto the disc during manufacturing, which CD players will ignore as non-audio tracks. The system could be disabled by tracing the outer edge of a CD with a felt-tip marker.[3]
- MediaMax CD3
- Installs software on the computer that tries to play the media so other software cannot read data directly from audio discs in the CD-ROM drive. Silently installing software on a computer created a controversy about modifying a computer's behaviour without a user's consent.
Console CD/DVD protection schemes[edit]
- Dreamcast (GD-ROM)
- Multiple table of contents (TOC) made normal cd player to not read beyond first track. However, one could read GD-ROM on CD reader by swapping the disc after reading fake TOC.
- FADE
- Creates fake scratches on the disk image which copying programs will automatically try to fix. Instead of alerting the user that the copied disc is detected, the program will play the game in a buggy manner.[4]
- PlayStation (CD-ROM)
- The authority pattern pressed on internal circumference of the media, which could not be copied, is used to detect authorized copies. Some titles also uses Libcrypt mechanism to validate the disc by using checksum as magic number to subroutines.
- PlayStation 2 (CD-ROM, DVD-ROM)
- A map file that contains all of the exact positions and file size info of the disc is stored at a position that is beyond the file limit. The game calls this place directly so that burned copy with no data beyond file limit cannot be played.
- PSP (Universal Media Disc)
- Since no blank media or writer exists, the media itself cannot be copied, but one could make ISO image (a file version of the UMD) on a memory card. The unique format also made the media difficult to adapt and expensive.
- Xbox (DVD)
- Two sets of media descriptors are used. Initially, and on typical DVD-ROM drives, only a short partition containing a brief DVD Video can be seen. The lead-out section of the disk stores a second set of media descriptors describing the bounds of the main partition. It also contains a partially-encrypted 'security sector' used for further authentication. The lead-out area is not typically directly accessible with consumer DVD-ROM hardware. Furthermore, the key for the security sector is located in the sector's raw header. This header information, unlike the raw headers of CD-ROM disks, is not accessible by default on nearly all DVD-ROM drives. Additional 'challenges' are implemented in the security sector through a table, with more challenge types added over the lifespan of Xbox and Xbox 360. These include, as an example from their earliest form, checks for unreadable sectors in predetermined ranges.
References[edit]
How To Rip Protected Cd
- ^'Macrovision Unveils SAFECAST Copy Protection Solution; SAFECAST Technology Designed to Secure Pre-Release Software from Unauthorized Copying. - Free Online Library'. www.thefreelibrary.com (Press release). 17 March 1999. Retrieved 23 September 2018.
- ^'Digital compact disc player security system reproducing method and apparatus'.
- ^Koerner, Brendan (3 June 2002). 'Can You Violate Copyright Law With a Magic Marker?'. Retrieved 5 May 2019.
- ^Grayson, Nathan (17 November 2011). 'Interview: Bohemia Interactive's CEO on fighting piracy, creative DRM'. Retrieved 11 February 2013.
Diablo 1 Cd Copy Protection
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