Content Protection for Recordable Media

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Content Protection for Recordable Media and Pre-Recorded Media (CPRM/CPPM) is a mechanism for controlling the copying, moving and deletion of digital media on a host device, such as a personal computer, or other digital player. It is a form of Digital Rights Management (DRM) developed by The 4C Entity, LLC (consisting of IBM, Intel, Matsushita and Toshiba).

CPRM has received nowhere near the attention of privacy rights advocates and the public, as has Windows Media DRM scheme and the Content Scrambling System (CSS), FairPlay or the other similar schemes.

The system was cracked early and is essentially dead. Free and commercial software that bypasses the protection is widely available^{[citation needed]} (it should be noted that bypassing CPRM/CPPM appears to be a violation of the DMCA, which would also mean that hosting such software or even linking to a website that host such software would also be prohibited, see Eric Corley article for further information).

The CPRM/CPPM Specification defines a renewable cryptographic method for protecting entertainment content when recorded on physical media. The currently implemented method utilizes the Cryptomeria cipher (C2) algorithm for symmetric encryption. The types of physical media supported include, but are not limited to, recordable DVD media and flash memory (note that the available 0.9 revision includes only the portions of the specification covering DVD media). The most widespread use of CPRM is arguably in Secure Digital cards.

A controversial proposal to embed CPRM in ATA hard drives was abandoned after popular outcry in 2001^[1]. However, as of 2006, CPRM is widely deployed in the popular Secure Digital card consumer-electronics flash memory format with little notice from electronic personal-rights advocates.

It is probably significant that although CPRM-capable storage formats such as Secure Digital are now widely available, the use of CPRM in these formats is not mandatory. Users are able to ignore the rights-management features entirely if they so choose, and for example can freely copy MP3 music files to and from personal music players or PDAs based on Secure Digital cards with no restrictions. Only special CPRM-enabled media formats, which do not yet seem to have achieved market visibility, will impose copying restrictions.

The use of the CPRM specification and access to the intellectual property and cryptographic materials required to implement it requires a license from 4C Entity, LLC. The license includes a facsimile key for the product which uses CPRM/CPPM technology.