Dear member of SanDisk Community, welcome.
Well, sorry for the delay, but it is a very specific topic.
Give the information as the theme works, but does not depend on users, if not of companies (trade secrets and restricted licenses).
CPRM (Content Protection for recorded media)
All SD cards have copyright protection for SD standard data types.
T his enables commercial distributors to put music or other media on the device so that it’s protected from illegal copying.
The technology behind this SD card feature is called Content Protection for Recordable Media (CPRM).
CPRM was developed by the 4C Entity, LCC, the organization handling copyright protection licensing for IBM, Intel, and SD co-founders Panasonic and Toshiba.
4C Entity also developed the related technology Content Protection for Pre-recorded Media (CPPM), which relates to the DVD-Audio format for music.
CPRM and CPPM are generally associated with flash and DVD media formats.
CPRM doesn’t apply automatically just because you’re using an SD card.
In order for data to be protected with CPRM , the device that’s writing the data must first create a Media Identifier and Media Key Block (MKB) on the SD card.
The Media Identifier and MKB are written to a physical portion of the SD card known as the Protected Area.
Data stored in the Protected Area , is inaccessible through the SD card’s file system, but any CPRM-enabled device reading the SD card can use it for content protection operations.
To protect data with CPRM, a device uses the Media Identifier and MKB to encode the data as it’s written to the SD card.
To read the data, a CPRM-enabled device accesses the Media Identify and MKB and uses them to decrypt the data as it’s read from the SD card.
Therefore, even if you copy the CPRM-protected files from the SD card’s file system, you won’t be able to read them outside of that SD card.
Regards, Alfred. (Google translated)