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The “protected area” was probably reserved for DRM keys for video distribution, an envisioned use case that never took off for SD cards, and hasn’t been relevan
by em500 1y ago
The “protected area” was probably reserved for DRM keys for video distribution, an envisioned use case that never took off for SD cards, and hasn’t been relevant for at least a decade.
https://www.sdcard.org/developers/sd-standard-overview/content-protection/ https://www.sdcard.org/developers/sd-standard-overview/conte...
- dcminter 1y agoYeah, I'm vaguely aware of this - jsut because of the "S" in SD standing for "Secure" as a euphemism for DRM stuff. From your link it seems likely that most cards probably don't even support it nowadays, but I'm still kind of curious about how exactly it was intended to be accessed - for example what extended commands might have been available. Presumably there's a spec somewhere for it, and presumably one can at the bare minimum ask a card "do you have a protected area available?"
- smaudet 1y agoI'd be interested in the specific commands/spec too, however as with all DRM techs I wouldn't be surprised if it's hidden behind NDAs. However you can see from the parent comment: > Success of mutual authentication enables host to access card protected area. So it's something the memory control must make available after a handshake, and then I presume either some specific memory address or set of retrieval commands would follow. As you mention, it also states this spec is now optional.
- dcminter 1y agoThis seems to be the spec in question: https://picture.iczhiku.com/resource/eetop/wYKESjuFHlDHkbcM.pdf https://picture.iczhiku.com/resource/eetop/wYKESjuFHlDHkbcM....