Victory for CPRM: SD cards overtake Compact Flash

December 30, 2003

With the popularity of compact portable digital audio players and PDA's with most using Secure Digital memory cards for memory expansion, the sales of SD cards have finally overtaken Compact Flash sales. In October, SD had a 30% share of the US flash memory market with a 28.8% share on CF and a 22% share on Sony's Memory stick flash.

Secure Digital memory cards were designed for storing DRM protected audio & video tracks, files or executables to prevent unauthorised sharing and redistribution using similar CPRM technology of DVD-Audio. While SD may have a large market share of flash media sales, nearly all current devices that use secure digital do not make use of SD's secure DRM features.

The ATA standards body tried incorporating CPRM into the full ATA specification for protecting media on fixed hard drives, but proved unsuccessful as they were easily defeated. As a result, some hard drive manufacturers have also tried implementing their own proprietary DRM schemes in their hard-drives. These CPRM features may not be of any use
until the release of Microsoft's Next Generation Secure Computing Base (originally known as
Palladium ) where the OS itself can enforce the DRM restrictions. It is quite likely
that Microsoft's
NGSCB will also make use of Secure Digital's CPRM features.

It's three years since we first heard of CPRM (Content Protection for Recordable Media), the digital rights management technology, but it's only in recent weeks that it's taken a decisive edge.

CPRM is designed to restrict the movement of digital files (which could be content or executables) according to rights set by the copyright owner, rather than the computer users, and it presents a formidable obstacle to crackers.

The CPRM-protected Secure Digital format grabbed 30 per cent of the US flash memory market in October, overtaking Compact Flash for the first time. CF took 28.8 per cent share and Sony's Memory Stick formats 22 per cent, according to the market research firm NPD Group. Although technically antiquated, CF still enjoys economies of scale from its long leadership, with 1 GB cards retailing for about 0.

CPRM was developed at IBM's Almaden Lab with support from Intel and the largest two manufacturers behind SD, Matsushita and Toshiba.

Support for CPRM found its way into the SCSI standard, and was being handled by the ATA standards body T.13 at the sub-committee level responsible for removable media. However, the first time that most people heard of it was when moves to incorporate CPRM into the full ATA specification used by fixed hard drives came to light. Those proposals, and a resulting compromise - which may have permitted CPRM-like DRM schemes, but flushed them out into the open - were eventually defeated.

In addition to raising awareness of share-denial technology and the value of open computing platforms, the episode probably had two lasting consequences.

Firstly, it pushed disk-based DRM 'underground'. Hard disk manufacturers use private proprietary commands and the T.13 ATA committee simply tries to ratify a common subset. DRM schemes today use private commands. Secondly, the defeat of CPRM on ATA probably swung the copyright owners' behind lock-down TCPA architectures as the solution to 'piracy'. Although TCPA advocates plead the Wernher von Braun defense ("The rockets go up…") it's incontestable that a 'trusted system' such as Microsoft's Next Generation Secure Computing Base (NGSCB aka Palladium) can prevent system level hacks which defeat copying restrictions.

When I originally heard of SD flash, I thought that it was definitely one thing that was not going to do well. Once I handled SD flash, I cannot see it any different from compact flash other than its small physical size and a 'write-protect' tab. So far, I have yet to see any equipment to make use of the CPRM features of secure digital.

Discuss and read more about copy protection systems on our Copy Protection Discussion Forum.

Source: The Register