[linux-minidisc] Inclusion of NetMD encryption keys in the master source

[Adrian Glaubitz <glaubitz@physik.fu-berlin.de>]

Dear linux-minidisc list followers,

as you might have seen from our last commit [1], we have now included
the encryption keys which are required to allow for transfers of audio to
NetMD devices. Despite the fact that we were never granted the permission
by Sony Japan to publish any of the keys employed in the original software,
SonicStage and it's security and DRM stack, OpenMG, we are still
able now to provide you with the necessary keys for NetMD transfers.

The trick is that NetMD uses a session-based encryption which is
valid for the actual transfer only. This means, that all audio is
eventually stored unencrypted on the MiniDisc medium. So,
in order to be able to transfer audio data to a NetMD device, it
is not required to know a specific, secret key owned by Sony, but
rather, only finding a key which the NetMD device will accept
as a valid key for a transfer. Since we have thoroughly examined
and understood OpenMG and it's underlying encryption to date,
we were able to calculate our own valid keys which are accepted
by any NetMD device for a secure transfer. We have thus calculated
our own valid set of keys and included them into the upstream
source as seen in the recent commit. Since we have calculated
these keys our own and they cannot be used for any other purpose
except allowing a valid, encrypted transfer to a NetMD device,
we are very confident that it is 100% legal to adapt and distribute
these keys as open source.

To simplify things for the users, I have created updated packages
in my Ubuntu Launchpad PPA and highly encourage everyone
on Ubuntu to install and test the packages [2]. It's very helpful
to receive some feedback on whether the keys are actually
working with all NetMD devices.

With the recent commit, we have now a complete, but highly
experimental free implementation of the NetMD protocol in Python. The next
step would therefore now to port the code to a lean and well-designed
C code to lift the NetMD support out of the experimental zone into
something useful for productive use. Many users are in fact a
bit overwhelmed by the complexity and rather cumbersome usage
of the Python scripts. As we've been planning a C port of the
Python code for a long time, we had already one developer who
has started porting the code. His preliminary work can be found
here [3]. If anyone on this list feels obliged to help us in this regard,
please go ahead. We, and most of our users, would highly
encourage a polished NetMD support, as most of the MiniDisc
devices with USB out there support NetMD and not HiMD. A
C port will eventually allow the integration into the main
UI application, QHiMDTransfer.

As always, we are looking forward to any suggestions and feedback
on the current code.

Regards,

Adrian

[1] https://lists.fu-berlin.de/pipermail/linux-minidisc/2011-March/msg00017.html
[2] https://launchpad.net/~glaubitz/+archive/linux-minidisc
[3] http://users.physik.fu-berlin.de/~glaubitz/linux-minidisc/mdlib.tar.gz